RE: Can you help me with this memoization simple example?
I am not sure if it was made clear that there is a general rule in python for
what is HASHABLE and lists are changeable while tuples are not so the latter
can be hashed as a simple copy of a list, albeit the contents must also be
immutable.
The memorize function uses a dictionary to store things and thus the things are
hashed to decide how to store it in the inner representation of a dictionary
and anything new that you want to look up in the dictionary has similar
considerations as it is hashed to see where in the dictionary to look for it.
Of course, if you add enough overhead and the memorize function you make gets
relatively few requests that are identical, it may not be worthwhile.
-Original Message-
From: Python-list On
Behalf Of MRAB via Python-list
Sent: Sunday, March 31, 2024 3:24 PM
To: python-list@python.org
Subject: Re: Can you help me with this memoization simple example?
On 2024-03-31 09:04, marc nicole wrote:
> Thanks for the first comment which I incorporated
>
> but when you say "You can't use a list as a key, but you can use a
> tuple as a key,
> provided that the elements of the tuple are also immutable."
>
> does it mean the result of sum of the array is not convenient to use
> as key as I do?
> Which tuple I should use to refer to the underlying list value as you
> suggest?
>
I was suggesting using `tuple` on the argument:
def memoize(f):
cache = {}
def g(*args):
key = tuple(args[0]), args[1]
if key not in cache:
cache[key] = f(args[0], args[1])
return cache[key]
return g
> Anything else is good in my code ?
>
> Thanks
>
> Le dim. 31 mars 2024 à 01:44, MRAB via Python-list
> a écrit :
>
> On 2024-03-31 00:09, marc nicole via Python-list wrote:
> > I am creating a memoization example with a function that adds up
> / averages
> > the elements of an array and compares it with the cached ones to
> retrieve
> > them in case they are already stored.
> >
> > In addition, I want to store only if the result of the function
> differs
> > considerably (passes a threshold e.g. 50 below).
> >
> > I created an example using a decorator to do so, the results
> using the
> > decorator is slightly faster than without the memoization which
> is OK, but
> > is the logic of the decorator correct ? anybody can tell me ?
> >
> > My code is attached below:
> >
> >
> >
> > import time
> >
> >
> > def memoize(f):
> > cache = {}
> >
> > def g(*args):
> > if args[1] == "avg":
> > sum_key_arr = sum(list(args[0])) / len(list(args[0]))
>
> 'list' will iterate over args[0] to make a list, and 'sum' will
> iterate
> over that list.
>
> It would be simpler to just let 'sum' iterate over args[0].
>
> > elif args[1] == "sum":
> > sum_key_arr = sum(list(args[0]))
> > if sum_key_arr not in cache:
> > for (
> > key,
> > value,
> > ) in (
> > cache.items()
> > ): # key in dict cannot be an array so I use the
> sum of the
> > array as the key
>
> You can't use a list as a key, but you can use a tuple as a key,
> provided that the elements of the tuple are also immutable.
>
> > if (
> > abs(sum_key_arr - key) <= 50
> > ): # threshold is great here so that all
> values are
> > approximated!
> > # print('approximated')
> > return cache[key]
> > else:
> > # print('not approximated')
> > cache[sum_key_arr] = f(args[0], args[1])
> > return cache[sum_key_arr]
> >
> > return g
> >
> >
> > @memoize
> > def aggregate(dict_list_arr, operation):
> > if operation == "avg":
> > return sum(list(dict_list_arr)) / len(list(dict_list_arr))
> > if operation == "sum":
> > return sum(list(dict_list_arr))
> > return None
> >
> >
> > t = time.time()
> > for i in range(200, 15000):
> > res = aggregate(list(range(i)), "avg")
> >
> > elapsed = time.time() - t
> > print(res)
> > print(elapsed)
>
>
> --
> https://mail.python.org/mailman/listinfo/python-list
>
--
https://mail.python.org/mailman/listinfo/python-list
--
https://mail.python.org/mailman/listinfo/python-list
Re: Can you help me with this memoization simple example?
On 2024-03-31 09:04, marc nicole wrote:
Thanks for the first comment which I incorporated
but when you say "You can't use a list as a key, but you can use a
tuple as a key,
provided that the elements of the tuple are also immutable."
does it mean the result of sum of the array is not convenient to use
as key as I do?
Which tuple I should use to refer to the underlying list value as you
suggest?
I was suggesting using `tuple` on the argument:
def memoize(f):
cache = {}
def g(*args):
key = tuple(args[0]), args[1]
if key not in cache:
cache[key] = f(args[0], args[1])
return cache[key]
return g
Anything else is good in my code ?
Thanks
Le dim. 31 mars 2024 à 01:44, MRAB via Python-list
a écrit :
On 2024-03-31 00:09, marc nicole via Python-list wrote:
> I am creating a memoization example with a function that adds up
/ averages
> the elements of an array and compares it with the cached ones to
retrieve
> them in case they are already stored.
>
> In addition, I want to store only if the result of the function
differs
> considerably (passes a threshold e.g. 50 below).
>
> I created an example using a decorator to do so, the results
using the
> decorator is slightly faster than without the memoization which
is OK, but
> is the logic of the decorator correct ? anybody can tell me ?
>
> My code is attached below:
>
>
>
> import time
>
>
> def memoize(f):
> cache = {}
>
> def g(*args):
> if args[1] == "avg":
> sum_key_arr = sum(list(args[0])) / len(list(args[0]))
'list' will iterate over args[0] to make a list, and 'sum' will
iterate
over that list.
It would be simpler to just let 'sum' iterate over args[0].
> elif args[1] == "sum":
> sum_key_arr = sum(list(args[0]))
> if sum_key_arr not in cache:
> for (
> key,
> value,
> ) in (
> cache.items()
> ): # key in dict cannot be an array so I use the
sum of the
> array as the key
You can't use a list as a key, but you can use a tuple as a key,
provided that the elements of the tuple are also immutable.
> if (
> abs(sum_key_arr - key) <= 50
> ): # threshold is great here so that all
values are
> approximated!
> # print('approximated')
> return cache[key]
> else:
> # print('not approximated')
> cache[sum_key_arr] = f(args[0], args[1])
> return cache[sum_key_arr]
>
> return g
>
>
> @memoize
> def aggregate(dict_list_arr, operation):
> if operation == "avg":
> return sum(list(dict_list_arr)) / len(list(dict_list_arr))
> if operation == "sum":
> return sum(list(dict_list_arr))
> return None
>
>
> t = time.time()
> for i in range(200, 15000):
> res = aggregate(list(range(i)), "avg")
>
> elapsed = time.time() - t
> print(res)
> print(elapsed)
--
https://mail.python.org/mailman/listinfo/python-list
--
https://mail.python.org/mailman/listinfo/python-list
Re: Can you help me with this memoization simple example?
Thanks for the first comment which I incorporated
but when you say "You can't use a list as a key, but you can use a tuple as
a key,
provided that the elements of the tuple are also immutable."
does it mean the result of sum of the array is not convenient to use as
key as I do?
Which tuple I should use to refer to the underlying list value as you
suggest?
Anything else is good in my code ?
Thanks
Le dim. 31 mars 2024 à 01:44, MRAB via Python-list
a écrit :
> On 2024-03-31 00:09, marc nicole via Python-list wrote:
> > I am creating a memoization example with a function that adds up /
> averages
> > the elements of an array and compares it with the cached ones to retrieve
> > them in case they are already stored.
> >
> > In addition, I want to store only if the result of the function differs
> > considerably (passes a threshold e.g. 50 below).
> >
> > I created an example using a decorator to do so, the results using the
> > decorator is slightly faster than without the memoization which is OK,
> but
> > is the logic of the decorator correct ? anybody can tell me ?
> >
> > My code is attached below:
> >
> >
> >
> > import time
> >
> >
> > def memoize(f):
> > cache = {}
> >
> > def g(*args):
> > if args[1] == "avg":
> > sum_key_arr = sum(list(args[0])) / len(list(args[0]))
>
> 'list' will iterate over args[0] to make a list, and 'sum' will iterate
> over that list.
>
> It would be simpler to just let 'sum' iterate over args[0].
>
> > elif args[1] == "sum":
> > sum_key_arr = sum(list(args[0]))
> > if sum_key_arr not in cache:
> > for (
> > key,
> > value,
> > ) in (
> > cache.items()
> > ): # key in dict cannot be an array so I use the sum of the
> > array as the key
>
> You can't use a list as a key, but you can use a tuple as a key,
> provided that the elements of the tuple are also immutable.
>
> > if (
> > abs(sum_key_arr - key) <= 50
> > ): # threshold is great here so that all values are
> > approximated!
> > # print('approximated')
> > return cache[key]
> > else:
> > # print('not approximated')
> > cache[sum_key_arr] = f(args[0], args[1])
> > return cache[sum_key_arr]
> >
> > return g
> >
> >
> > @memoize
> > def aggregate(dict_list_arr, operation):
> > if operation == "avg":
> > return sum(list(dict_list_arr)) / len(list(dict_list_arr))
> > if operation == "sum":
> > return sum(list(dict_list_arr))
> > return None
> >
> >
> > t = time.time()
> > for i in range(200, 15000):
> > res = aggregate(list(range(i)), "avg")
> >
> > elapsed = time.time() - t
> > print(res)
> > print(elapsed)
>
>
> --
> https://mail.python.org/mailman/listinfo/python-list
>
--
https://mail.python.org/mailman/listinfo/python-list
Re: Can you help me with this memoization simple example?
On 2024-03-31 00:09, marc nicole via Python-list wrote:
I am creating a memoization example with a function that adds up / averages
the elements of an array and compares it with the cached ones to retrieve
them in case they are already stored.
In addition, I want to store only if the result of the function differs
considerably (passes a threshold e.g. 50 below).
I created an example using a decorator to do so, the results using the
decorator is slightly faster than without the memoization which is OK, but
is the logic of the decorator correct ? anybody can tell me ?
My code is attached below:
import time
def memoize(f):
cache = {}
def g(*args):
if args[1] == "avg":
sum_key_arr = sum(list(args[0])) / len(list(args[0]))
'list' will iterate over args[0] to make a list, and 'sum' will iterate
over that list.
It would be simpler to just let 'sum' iterate over args[0].
elif args[1] == "sum":
sum_key_arr = sum(list(args[0]))
if sum_key_arr not in cache:
for (
key,
value,
) in (
cache.items()
): # key in dict cannot be an array so I use the sum of the
array as the key
You can't use a list as a key, but you can use a tuple as a key,
provided that the elements of the tuple are also immutable.
if (
abs(sum_key_arr - key) <= 50
): # threshold is great here so that all values are
approximated!
# print('approximated')
return cache[key]
else:
# print('not approximated')
cache[sum_key_arr] = f(args[0], args[1])
return cache[sum_key_arr]
return g
@memoize
def aggregate(dict_list_arr, operation):
if operation == "avg":
return sum(list(dict_list_arr)) / len(list(dict_list_arr))
if operation == "sum":
return sum(list(dict_list_arr))
return None
t = time.time()
for i in range(200, 15000):
res = aggregate(list(range(i)), "avg")
elapsed = time.time() - t
print(res)
print(elapsed)
--
https://mail.python.org/mailman/listinfo/python-list
Can you help me with this memoization simple example?
I am creating a memoization example with a function that adds up / averages
the elements of an array and compares it with the cached ones to retrieve
them in case they are already stored.
In addition, I want to store only if the result of the function differs
considerably (passes a threshold e.g. 50 below).
I created an example using a decorator to do so, the results using the
decorator is slightly faster than without the memoization which is OK, but
is the logic of the decorator correct ? anybody can tell me ?
My code is attached below:
import time
def memoize(f):
cache = {}
def g(*args):
if args[1] == "avg":
sum_key_arr = sum(list(args[0])) / len(list(args[0]))
elif args[1] == "sum":
sum_key_arr = sum(list(args[0]))
if sum_key_arr not in cache:
for (
key,
value,
) in (
cache.items()
): # key in dict cannot be an array so I use the sum of the
array as the key
if (
abs(sum_key_arr - key) <= 50
): # threshold is great here so that all values are
approximated!
# print('approximated')
return cache[key]
else:
# print('not approximated')
cache[sum_key_arr] = f(args[0], args[1])
return cache[sum_key_arr]
return g
@memoize
def aggregate(dict_list_arr, operation):
if operation == "avg":
return sum(list(dict_list_arr)) / len(list(dict_list_arr))
if operation == "sum":
return sum(list(dict_list_arr))
return None
t = time.time()
for i in range(200, 15000):
res = aggregate(list(range(i)), "avg")
elapsed = time.time() - t
print(res)
print(elapsed)
--
https://mail.python.org/mailman/listinfo/python-list
Re: Fwd: Can you help me with this Python question?
Well, although I never used pandas and never will, if that's about artworks, that's mine. Obviously, you need to iterate columns and sum values returned by the snippet you provided. A quick search tells us to use colums property. So, it might look like this: na_sum = sum(df[name].isnull().sum() for name in df.columns) Axy On 13/10/2022 13:44, Sarah Wallace wrote: For a python class I am taking.. In this challenge, you'll be working with a DataFrame that contains data about artworks, and it contains many missing values. Your task is to create a variable called na_sum that contains the total number of missing values in the DataFrame. When that's completed, print out your answer! Hint: The code given below will give you the number of missing (NaN) values for the *Name* column in the DataFrame. How would you edit the code to get the missing values for every column in the DataFrame? Extra hint: You'll be returning a single number which is the final sum() of everything. df['Name'].isnull().sum() -- https://mail.python.org/mailman/listinfo/python-list
Fwd: Can you help me with this Python question?
For a python class I am taking.. In this challenge, you'll be working with a DataFrame that contains data about artworks, and it contains many missing values. Your task is to create a variable called na_sum that contains the total number of missing values in the DataFrame. When that's completed, print out your answer! Hint: The code given below will give you the number of missing (NaN) values for the *Name* column in the DataFrame. How would you edit the code to get the missing values for every column in the DataFrame? Extra hint: You'll be returning a single number which is the final sum() of everything. df['Name'].isnull().sum() -- Thanks! *Sarah Wallace* sarah.wallac...@gmail.com -- Thanks! *Sarah Wallace* sarah.wallac...@gmail.com 214.300.1064 -- https://mail.python.org/mailman/listinfo/python-list
Re: Help me with this code
chovd...@gmail.com writes: > Hi friends > > help me with the following code. Im able to execute the code but getting > wrong output > > def sequence_b(N): > N = 10 > result = 0 > for k in xrange (1,N): > result += ((-1) ** (k+1))/2*k-1 > print result > print sequence_b(10) > > This is the output which im getting > -1 > -4 > -5 > -10 > -11 > -18 > -19 > -28 > -29 > > > But i want output as > 1 > -1/3 > 1/5 > -1/7 > 1/9 > -1/11 > 1/13 > -1/15 > 1/17 > -1/19 You probably want this: N = 10 result = 0 for k in range (1,N): step = ((-1)**(k+1))/(2*k-1) result += step print(step) Note: 1. You don't use the parameter N, you immediately change it to 10. Leave the line N = 10 out. 2. Your function doesn't return its result, so it returns None. So the print sequence_b(10) dosn't make sense. If the print is only for debugging the use the following: def sequence_b(N): result = 0 for k in range (1,N): step = ((-1)**(k+1))/(2*k-1) print(step) ## debug output result += step return result print(sequence_b(10)) # print the result of the function call [I use print() because I use Python 3] -- Piet van Oostrum WWW: http://pietvanoostrum.com/ PGP key: [8DAE142BE17999C4] -- https://mail.python.org/mailman/listinfo/python-list
Re: Help me with this code PLEASE
On 2013-11-06, Denis McMahon wrote: > On Wed, 06 Nov 2013 00:35:56 +0200, Nick the Gr33k wrote: > >> Now i realizes i just cannot store lists into it's columns because it >> does not support a collection datatype. > > All databases support storing of collections, but *NOT THE WAY YOU WANT > TO DO IT* > > You refuse to do it the proper way, so you have to bodge a solution > oh wait I'm having a flashback here To quote the great Casey Stengel "it's deja vu all over again". http://www.bostonbaseball.com/whitesox/baseball_extras/yogi.html -- Grant Edwards grant.b.edwardsYow! I feel like a wet at parking meter on Darvon! gmail.com -- https://mail.python.org/mailman/listinfo/python-list
Re: Help me with this code PLEASE
On Wed, Nov 6, 2013 at 3:49 AM, Mark Lawrence wrote: > On 06/11/2013 01:14, Nick the Gr33k wrote: >> >> >> How, do i i proceed? > > > If at first you don't succeed, keep asking on comp.lang.python until someone > gives me the completely bodged solution that I keep asking for even if it's > complete nonsense. > > > -- > Python is the second best programming language in the world. > But the best has yet to be invented. Christian Tismer > > Mark Lawrence > > -- > https://mail.python.org/mailman/listinfo/python-list Nikos, I believe we are passed the time again where your enquiries slip from legitimate questions to trolling behavior. As was pointed out you aren't close to any solution. You should go off taking the advice and tutoring you have had here, do some reading (yes, actually learn and understand something), perhaps start from scratch reading basics of computer programming, databases, html, unicode, operating systems, web servers, etc. and come back when you have a solid basis to ask a question. I take my profession seriously. Its fun, but it takes a lot of reading and studying and practice to be good at it. The fact that you even presume that you are doing what software designers, or engineers or programmers do to ply the craft is disgusting. Its not that you don't know, its that you don't know and are an arrogant idiot to assume that you do. Your threads all end up being a very poor man's version of the movie Ground Hog Day. The fact that you don't recognize how rude and insulting you are, and how little you bring to the discussion will inevitably lead to more personal attacks since you aren't holding up your end of the technical back and forth. Your repeated behavior of starting new threads is just a boring childish method to demand attention. You have our attention. I believe that most of us if not all of us think you are the most aggravating, incompetent, rude, needy, manipulating, person we have ever seen online ever. Go away, and come back (months from now at least) when you have some redeeming human qualities. -- Joel Goldstick http://joelgoldstick.com -- https://mail.python.org/mailman/listinfo/python-list
Re: Help me with this code PLEASE
On 06/11/2013 01:14, Nick the Gr33k wrote: How, do i i proceed? If at first you don't succeed, keep asking on comp.lang.python until someone gives me the completely bodged solution that I keep asking for even if it's complete nonsense. -- Python is the second best programming language in the world. But the best has yet to be invented. Christian Tismer Mark Lawrence -- https://mail.python.org/mailman/listinfo/python-list
Re: Help me with this code PLEASE
Op 05-11-13 22:26, Nick the Gr33k schreef: > I know i'm close to solution, i can feel it but i have some issues. > The code we arr discussing is the following: No you are not. You are just doing random changes, without any understanding. If you had followed my suggestion and actually read the documentation of fetchone, you would have realised this wouldn't have worked either. Your resistance to reading the documentation is making you lose more time than you hoped to win by just going ahead and trying things blindly. > [Tue Nov 05 23:21:52 2013] [error] [client 176.92.96.218] File > "/home/nikos/public_html/cgi-bin/metrites.py", line 274, in > [Tue Nov 05 23:21:52 2013] [error] [client 176.92.96.218] visit = > visit.split() > [Tue Nov 05 23:21:52 2013] [error] [client 176.92.96.218] > AttributeError: 'NoneType' object has no attribute 'split' This is essentially the same error you had before. You have an object of NoneType where you expect something different. Changing your code to use split instead of iteration won't change the fact that you have an object of NoneType. -- Antoon Pardon -- https://mail.python.org/mailman/listinfo/python-list
Re: Help me with this code
On Tue, 5 Nov 2013 17:51:00 -0800 (PST), chovd...@gmail.com wrote: result += ((-1) ** (k+1))/2*k-1 One of two things are happening here. Maybe both. You're using Python 2.x (and should havesaid so) where integer division is truncated. You're missing around some part of the intended denominator. Check operator precedence rules. -- DaveA -- https://mail.python.org/mailman/listinfo/python-list
Re: Help me with this code
On Tue, 05 Nov 2013 17:51:00 -0800, chovdary wrote: > Hi friends > > help me with the following code. Im able to execute the code but getting > wrong output [snip code] You have this critical expression in your code: result += ((-1) ** (k+1))/2*k-1 It looks to me like you are using Python 2. Unfortunately, Python 2 had a design flaw that wasn't corrected until Python 3, where division is the integer division operator: 1/2 => 0 rather than 0.5. There are three ways to fix this: 1) convert one of the numbers to a float: result += float((-1) ** (k+1))/2*k-1 will probably do the trick. Although I'm not sure if the denominator is meant to be just 2, as you have above, or (2*k-1). 2) Put "from __future__ import division" as the very first line of your program. It must appear before any other code. 3) Avoid floating point numbers and use actual fractions, which will give you exact values instead of approximate. At the beginning of your code, put from fractions import Fraction and then change the code to look something like this: result += Fraction((-1) ** (k+1))/Fraction(2*k-1) -- Steven -- https://mail.python.org/mailman/listinfo/python-list
Re: Help me with this code
On 06/11/2013 01:51, chovd...@gmail.com wrote: Hi friends help me with the following code. Im able to execute the code but getting wrong output def sequence_b(N): N = 10 result = 0 for k in xrange (1,N): result += ((-1) ** (k+1))/2*k-1 print result print sequence_b(10) This is the output which im getting -1 -4 -5 -10 -11 -18 -19 -28 -29 But i want output as 1 -1/3 1/5 -1/7 1/9 -1/11 1/13 -1/15 1/17 -1/19 1. Multiplication and division take precedence over addition and subtraction, and both multiplication/division and addition/subtraction are calculated left-to-right, so an expression like x/2*k-1 is calculated as ((x/2)*k)-1. 2. In Python 2, dividing an integer by an integer gives an integer result, e.g. 7/2 gives 3, not 3.5. The simplest way of fixing that is to introduce a float into either the numerator or denominator. That means that your expression should be, say: ((-1) ** (k + 1)) / (2.0 * k - 1) 3. It won't print fractions like 1/5, but instead decimals like 0.2. 4. You're adding the result of the expression to 'result' and then printing the value of 'result', so your output would be the results of: -1 -1+(-1/3) -1+(-1/3)+(1/5) and so on. 5. Your function prints the result but doesn't return anyhing, so, by default, it'll return None. Therefore, 'print sequence_b(10)' will print 'None'. What you'll get is a series of numbers and then a None. -- https://mail.python.org/mailman/listinfo/python-list
Representing fractions (was: Help me with this code)
chovd...@gmail.com writes: > def sequence_b(N): > N = 10 > result = 0 > for k in xrange (1,N): > result += ((-1) ** (k+1))/2*k-1 Every number here is an integer. Python 2 will keep all the computations integers by default:: $ python2 >>> 1 / 2 0 You want to use Python 3, which does “true division” by default:: $ python3 >>> 1 / 2 0.5 > But i want output as > 1 > -1/3 > 1/5 > -1/7 > 1/9 > -1/11 > 1/13 > -1/15 > 1/17 > -1/19 You're not going to get that output from Python built-in number types. If you want numbers which represent fractions (as opposed to integers, or decimal numbers, or floating-point numbers), you want the ‘fractions’ module http://docs.python.org/3/library/fractions.html> which will represent the number explicitly with numerator and denominator:: $ python3 >>> import fractions >>> result = fractions.Fraction(1) / fractions.Fraction(2) >>> result Fraction(1, 2) >>> print(result) 1/2 -- \ “A hundred times every day I remind myself that […] I must | `\ exert myself in order to give in the same measure as I have | _o__)received and am still receiving” —Albert Einstein | Ben Finney -- https://mail.python.org/mailman/listinfo/python-list
Help me with this code
Hi friends help me with the following code. Im able to execute the code but getting wrong output def sequence_b(N): N = 10 result = 0 for k in xrange (1,N): result += ((-1) ** (k+1))/2*k-1 print result print sequence_b(10) This is the output which im getting -1 -4 -5 -10 -11 -18 -19 -28 -29 But i want output as 1 -1/3 1/5 -1/7 1/9 -1/11 1/13 -1/15 1/17 -1/19 -- https://mail.python.org/mailman/listinfo/python-list
Re: Help me with this code PLEASE
Denis McMahon writes: > You have been told several times by several people how to do this > properly. You insist on using your bodged up solution instead. OK, we'll > all try and help you bodge up a solution[…] Why? No-one here is obligated to help with implementing a solution we agree is bad. Now that helpful suggestions have been offered, and the OP continues to obstinately refuse to learn, why not leave it there? Why not leave this person to his own obstinacy and stop giving him the attention he demands? -- \ “Computers are useless. They can only give you answers.” —Pablo | `\ Picasso | _o__) | Ben Finney -- https://mail.python.org/mailman/listinfo/python-list
Re: Help me with this code PLEASE
Στις 6/11/2013 12:54 πμ, ο/η John Gordon έγραψε: The code i provided only worked once before it failed and managed to store this: counterID,host,refs,city,userOS,browser,visits,hits,download - 1, 176-92-96-218.adsl.cyta.gr, Europe/Athens, Windows, Chrome, -00-00 00:00:00, 1, '' You've got a data inconsistancy here. You give nine column names, but only eight values. It's impossible to tell which value belongs to which column. Which value is missing? Yes, you have a point but thats why because 'refs' was an empty string for some reason and i have should have made this clear by putting a '' like i did with the 'downloads' at the end. So it is not a matter of inconsistency. Its weird though why it was stored this way, refs and downloads that is as an empty strings. How, do i i proceed? -- https://mail.python.org/mailman/listinfo/python-list
Re: Help me with this code PLEASE
On Wed, 06 Nov 2013 00:35:56 +0200, Nick the Gr33k wrote: > Now i realizes i just cannot store lists into it's columns because it > does not support a collection datatype. All databases support storing of collections, but *NOT THE WAY YOU WANT TO DO IT* You refuse to do it the proper way, so you have to bodge a solution oh wait I'm having a flashback here You have been told several times by several people how to do this properly. You insist on using your bodged up solution instead. OK, we'll all try and help you bodge up a solution, but I will tell you now, in advance, in very clear terms: *ONE DAY YOUR BODGED UP SOLUTION WILL BREAK BECAUSE THE TOTAL LIST OF TORRENTS THAT A USER HAS DOWNLOADED, WHEN PACKAGED INTO A STRING, WILL BE BIGGER THAN THE DATABASE STRING FIELD YOU ASSIGNED* There may be another issue that you need to consider. Supposing a torrent file name is 40 characters long. Supposing a user downloads up to 20 torrents a day. That means in one year, their list will contain 7300 entries, and the character string in the database will be 365 * 20 * 40 + 365 * 20 - 1 = 299299 characters. And you're going to convert this huge string into a list and then back into a string 20 times a day for every user just to add another 40 characters to the end. Do you expect 100 users? 1,000? 10,000? 100,000? Let's assume that you have a million users. In a year, every day you're reading and writing about 6000 Gbytes a day from and to the database. Holy smoke batman, that's a lot of data. Or you could use the database properly, and just write the 40 byte torrent file name to the database with a pointer to the user's record every time a user downloads another torrent. -- Denis McMahon, denismfmcma...@gmail.com -- https://mail.python.org/mailman/listinfo/python-list
Re: Help me with this code PLEASE
On 05/11/2013 22:31, Cameron Simpson wrote: On 05Nov2013 20:09, Nikos wrote: O even better an rdbms than allows complex data such as tuples, lists, dicts to be saved into the db as they are so i dont have to cobvet back and forth each time. If you're just using the db for storage or adhoc and arbitrary python objects (and not querying the stored values via SQL - eg WHERE), then: make a column of type BLOB, convert Python values to bytes using pickle, store. And of course the reverse. It is not a great use of an RDB, but it seems to adhere to what you ask. How do expect the OP to understand a BLOB or pickle or chutney when he doesn't understand why he can't iterate around a Nonetype object? -- Python is the second best programming language in the world. But the best has yet to be invented. Christian Tismer Mark Lawrence -- https://mail.python.org/mailman/listinfo/python-list
Re: Help me with this code PLEASE
There is also the shelve module. It uses pickle to marshal a Python object, then stores it in a file under a key. Sample code from the module documentation: import shelve d = shelve.open(filename) # open -- file may get suffix added by low-level library d[key] = data # store data at key (overwrites old data if using an existing key) data = d[key] # retrieve a COPY of data at key (raise KeyError if no such key) del d[key] # delete data stored at key (raises KeyError if no such key) flag = key in d# true if the key exists klist = list(d.keys()) # a list of all existing keys (slow!) -- Bob Gailer 919-636-4239 Chapel Hill NC -- https://mail.python.org/mailman/listinfo/python-list
Re: Help me with this code PLEASE
On 05Nov2013 20:09, Nikos wrote: > O even better an rdbms than allows complex data such as tuples, > lists, dicts to be saved into the db as they are so i dont have to > cobvet back and forth each time. If you're just using the db for storage or adhoc and arbitrary python objects (and not querying the stored values via SQL - eg WHERE), then: make a column of type BLOB, convert Python values to bytes using pickle, store. And of course the reverse. It is not a great use of an RDB, but it seems to adhere to what you ask. -- Cameron Simpson -- https://mail.python.org/mailman/listinfo/python-list
Re: Help me with this code PLEASE
In Nick the Gr33k writes: > The code i provided only worked once before it failed and managed to > store this: > > counterID,host,refs,city,userOS,browser,visits,hits,download > - > 1, 176-92-96-218.adsl.cyta.gr, Europe/Athens, Windows, Chrome, > -00-00 00:00:00, 1, '' You've got a data inconsistancy here. You give nine column names, but only eight values. It's impossible to tell which value belongs to which column. Which value is missing? > 'visit's column is full of zeroes. Perhaps this is considered as Null > for Python? Python does not consider zero to be a null value. (It will compare as equal to False, but that's not the same.) > But ref is also null, why the code didn't complain for 'ref' which is > retrieved just before 'visits'? Are you sure refs is null? According to the sample values you gave, refs is 'Europe/Athens'. -- John Gordon Imagine what it must be like for a real medical doctor to gor...@panix.comwatch 'House', or a real serial killer to watch 'Dexter'. -- https://mail.python.org/mailman/listinfo/python-list
Re: Help me with this code PLEASE
On 05/11/2013 22:28, Nick the Gr33k wrote:
Στις 6/11/2013 12:06 πμ, ο/η John Gordon έγραψε:
In Nick the Gr33k
writes:
# fetch those columns that act as lists but are stored as
strings
cur.execute('''SELECT refs, visits, downloads FROM visitors
WHERE
counterID = %s and host = %s''', (cID, host) )
data = cur.fetchone()
if cur.rowcount:
# unpack data into variables
(ref, visit, download) = data
visit = visit.split()
[Tue Nov 05 23:21:52 2013] [error] [client 176.92.96.218] visit =
visit.split()
[Tue Nov 05 23:21:52 2013] [error] [client 176.92.96.218]
AttributeError: 'NoneType' object has no attribute 'split'
It appears that in the row you're fetching from the visitors table, the
'visits' column is NULL.
Your next step is track down why.
Indeed.
The code i provided only worked once before it failed and managed to
store this:
counterID,host,refs,city,userOS,browser,visits,hits,download
-
1, 176-92-96-218.adsl.cyta.gr, Europe/Athens, Windows, Chrome,
-00-00 00:00:00, 1, ''
'visit's column is full of zeroes. Perhaps this is considered as Null
for Python?
But ref is also null, why the code didn't complain for 'ref' which is
retrieved just before 'visits'?
How, i eman what si the way to investigate this further?
Don't worry about it. Just leave it with the crack team that I've put
together for you. We should have some answers some time tomorrow.
--
Python is the second best programming language in the world.
But the best has yet to be invented. Christian Tismer
Mark Lawrence
--
https://mail.python.org/mailman/listinfo/python-list
Re: Help me with this code PLEASE
Στις 6/11/2013 12:15 πμ, ο/η Piet van Oostrum έγραψε: Nick the Gr33k writes: IAM STRUGGLING WITH IT 2 DAYS NOW AND I CANNOT GET IT TO WORK. ALL I WANT IT TO DO IS JUST 1. RETRIEVE 3 COLUMNS THAT CONSIST OF 3 LONG STRINGS 2. CONVERT LONG STRINGS TO LISTS 3. ADD SOME CURRENT VALUES TO THOSE LISTS 4. CONVERT FROM LISTS TO LONG STRINGS SO I CAN STORE SUCCESSFULLY LIST PYTHON DATATYPE TO MYSQL SCALAR STRING. EVERYHTIGN I TRIED FAILED. Then why don't you use the simple solution: use a relational database to store the data? -- How you mean? Up until now i was using for years MySQL. Now i realizes i just cannot store lists into it's columns because it does not support a collection datatype. perhaps its time to use postgresql so to avoid these coversions? does postgresql support "collection" columns? and is its synta -- https://mail.python.org/mailman/listinfo/python-list
Re: Help me with this code PLEASE
Στις 6/11/2013 12:06 πμ, ο/η John Gordon έγραψε:
In Nick the Gr33k
writes:
# fetch those columns that act as lists but are stored as
strings
cur.execute('''SELECT refs, visits, downloads FROM visitors
WHERE
counterID = %s and host = %s''', (cID, host) )
data = cur.fetchone()
if cur.rowcount:
# unpack data into variables
(ref, visit, download) = data
visit = visit.split()
[Tue Nov 05 23:21:52 2013] [error] [client 176.92.96.218] visit =
visit.split()
[Tue Nov 05 23:21:52 2013] [error] [client 176.92.96.218]
AttributeError: 'NoneType' object has no attribute 'split'
It appears that in the row you're fetching from the visitors table, the
'visits' column is NULL.
Your next step is track down why.
Indeed.
The code i provided only worked once before it failed and managed to
store this:
counterID,host,refs,city,userOS,browser,visits,hits,download
-
1, 176-92-96-218.adsl.cyta.gr, Europe/Athens, Windows, Chrome,
-00-00 00:00:00, 1, ''
'visit's column is full of zeroes. Perhaps this is considered as Null
for Python?
But ref is also null, why the code didn't complain for 'ref' which is
retrieved just before 'visits'?
How, i eman what si the way to investigate this further?
--
https://mail.python.org/mailman/listinfo/python-list
Re: Help me with this code PLEASE
Nick the Gr33k writes: > > IAM STRUGGLING WITH IT 2 DAYS NOW AND I CANNOT GET IT TO WORK. > > ALL I WANT IT TO DO IS JUST > > 1. RETRIEVE 3 COLUMNS THAT CONSIST OF 3 LONG STRINGS > 2. CONVERT LONG STRINGS TO LISTS > 3. ADD SOME CURRENT VALUES TO THOSE LISTS > 4. CONVERT FROM LISTS TO LONG STRINGS SO I CAN STORE SUCCESSFULLY LIST > PYTHON DATATYPE TO MYSQL SCALAR STRING. > > EVERYHTIGN I TRIED FAILED. Then why don't you use the simple solution: use a relational database to store the data? -- Piet van Oostrum WWW: http://pietvanoostrum.com/ PGP key: [8DAE142BE17999C4] -- https://mail.python.org/mailman/listinfo/python-list
Re: Help me with this code PLEASE
In Nick the Gr33k
writes:
> # fetch those columns that act as lists but are stored as
> strings
> cur.execute('''SELECT refs, visits, downloads FROM visitors
> WHERE
> counterID = %s and host = %s''', (cID, host) )
> data = cur.fetchone()
> if cur.rowcount:
> # unpack data into variables
> (ref, visit, download) = data
>
> visit = visit.split()
>
> [Tue Nov 05 23:21:52 2013] [error] [client 176.92.96.218] visit =
> visit.split()
> [Tue Nov 05 23:21:52 2013] [error] [client 176.92.96.218]
> AttributeError: 'NoneType' object has no attribute 'split'
It appears that in the row you're fetching from the visitors table, the
'visits' column is NULL.
Your next step is track down why.
--
John Gordon Imagine what it must be like for a real medical doctor to
gor...@panix.comwatch 'House', or a real serial killer to watch 'Dexter'.
--
https://mail.python.org/mailman/listinfo/python-list
Re: Help me with this code PLEASE
On Wed, Nov 6, 2013 at 8:17 AM, Mark Lawrence wrote: > I've taken a different approach. I've put the contract out to tender and > hereby give you the winners > http://www.mudefordwoodcommunitycentre.co.uk/playgroup-and-tiny-tots/ Sounds good! But I don't see a list of their technologies - do they use open source tools like Python, or is it proprietary stuff like Fisher-Price(tm) "My First Website"? The latter is probably sufficient for these tasks, but I would hope that your contractors are able to master real-world problems too. Nikos, once again you are getting yourself into a tizz over this, because the problem is urgent to you. You need to stop programming professionally and make it a hobby, so that you remove the time pressure. You cope badly with pressure, so why torture yourself? Get into a completely different industry for your day job, and do all your programming in the evenings. You'll find lots of things easier and less stressful. ChrisA -- https://mail.python.org/mailman/listinfo/python-list
Re: Help me with this code PLEASE
On 05/11/2013 21:17, Mark Lawrence wrote: On 05/11/2013 20:19, John Gordon wrote: In Nick the Gr33k writes: IAM STRUGGLING WITH IT 2 DAYS NOW AND I CANNOT GET IT TO WORK. ALL I WANT IT TO DO IS JUST 1. RETRIEVE 3 COLUMNS THAT CONSIST OF 3 LONG STRINGS 2. CONVERT LONG STRINGS TO LISTS 3. ADD SOME CURRENT VALUES TO THOSE LISTS 4. CONVERT FROM LISTS TO LONG STRINGS SO I CAN STORE SUCCESSFULLY LIST PYTHON DATATYPE TO MYSQL SCALAR STRING. EVERYHTIGN I TRIED FAILED. How did it fail? Error message? No results at all? Different results than you wanted? If so, how did they differ? Dear John, This approach has already been tried by Dave Angel, Steven D'Aprano and Chris Angelico amongst others and has failed dismally so why should you be any different? I've taken a different approach. I've put the contract out to tender and hereby give you the winners http://www.mudefordwoodcommunitycentre.co.uk/playgroup-and-tiny-tots/ Part of the rationale is that they're literally 100 yards from my front door so communicating with them effectively should be extremely easy. This will be particularly useful when it comes down to debugging such difficult issues as "> TypeError: 'NoneType' object is not iterable". I'm looking forward to working in partnership with them and am convinced that within a few days all of Nikos' problems will have been solved. Oh dear it looks as if we might have to renegotiate the contract as I understand that we've an almost intractable problem to solve it's "AttributeError: 'NoneType' object has no attribute 'split'". -- Python is the second best programming language in the world. But the best has yet to be invented. Christian Tismer Mark Lawrence -- https://mail.python.org/mailman/listinfo/python-list
Re: Help me with this code PLEASE
Στις 5/11/2013 10:19 μμ, ο/η John Gordon έγραψε:
In Nick the Gr33k
writes:
IAM STRUGGLING WITH IT 2 DAYS NOW AND I CANNOT GET IT TO WORK.
ALL I WANT IT TO DO IS JUST
1. RETRIEVE 3 COLUMNS THAT CONSIST OF 3 LONG STRINGS
2. CONVERT LONG STRINGS TO LISTS
3. ADD SOME CURRENT VALUES TO THOSE LISTS
4. CONVERT FROM LISTS TO LONG STRINGS SO I CAN STORE SUCCESSFULLY LIST
PYTHON DATATYPE TO MYSQL SCALAR STRING.
EVERYHTIGN I TRIED FAILED.
How did it fail?
Error message?
No results at all?
Different results than you wanted? If so, how did they differ?
I know i'm close to solution, i can feel it but i have some issues.
The code we arr discussing is the following:
=
# ~ DATABASE INSERTS ~
=
if cookieID != 'nikos' and ( os.path.exists( path + page ) or
os.path.exists( cgi_path + page ) ) and re.search(
r'(amazon|google|proxy|cloud|reverse|fetch|msn|who|spider|crawl|ping)',
host ) is None:
try:
# if first time for webpage; create new record( primary key is
automatic, hit is defaulted ), if page exists then update record
cur.execute('''INSERT INTO counters (url) VALUES (%s) ON DUPLICATE KEY
UPDATE hits = hits + 1''', page )
cID = cur.lastrowid
# fetch those columns that act as lists but are stored as
strings
cur.execute('''SELECT refs, visits, downloads FROM visitors WHERE
counterID = %s and host = %s''', (cID, host) )
data = cur.fetchone()
ref = visit = download = []
if cur.rowcount:
# unpack data into variables
(ref, visit, download) = data
# retrieve long strings and convert them into lists
respectively
ref = ref.split()
visit = visit.split()
download = download.split()
else:
# initiate these values
ref = ref
visit = lastvisit
download = ''
refs = visits = downloads = []
# add current values to each list respectively
refs.append( ref )
visits.append( visit )
downloads.append( download )
# convert lists back to longstrings
refs = ', '.join( refs )
visits = ', '.join( visits )
downloads = ', '.join( downloads )
# save this visit as an entry into database
cur.execute('''INSERT INTO visitors (counterID, refs, host, city,
useros, browser, visits, downloads) VALUES (%s, %s, %s, %s, %s, %s, %s, %s)
ON DUPLICATE KEY UPDATE refs = %s, visits = %s, hits = hits + 1,
downloads = %s''',
(cID, refs, host, city, useros, browser, visits, downloads, refs,
visits, downloads) )
con.commit()
except pymysql.ProgrammingError as e:
print( repr(e) )
con.rollback()
sys.exit(0)
===
[Tue Nov 05 23:21:52 2013] [error] [client 176.92.96.218] File
"/home/nikos/public_html/cgi-bin/metrites.py", line 274, in
[Tue Nov 05 23:21:52 2013] [error] [client 176.92.96.218] visit =
visit.split()
[Tue Nov 05 23:21:52 2013] [error] [client 176.92.96.218]
AttributeError: 'NoneType' object has no attribute 'split'
--
https://mail.python.org/mailman/listinfo/python-list
Re: Help me with this code PLEASE
On 05/11/2013 20:19, John Gordon wrote: In Nick the Gr33k writes: IAM STRUGGLING WITH IT 2 DAYS NOW AND I CANNOT GET IT TO WORK. ALL I WANT IT TO DO IS JUST 1. RETRIEVE 3 COLUMNS THAT CONSIST OF 3 LONG STRINGS 2. CONVERT LONG STRINGS TO LISTS 3. ADD SOME CURRENT VALUES TO THOSE LISTS 4. CONVERT FROM LISTS TO LONG STRINGS SO I CAN STORE SUCCESSFULLY LIST PYTHON DATATYPE TO MYSQL SCALAR STRING. EVERYHTIGN I TRIED FAILED. How did it fail? Error message? No results at all? Different results than you wanted? If so, how did they differ? Dear John, This approach has already been tried by Dave Angel, Steven D'Aprano and Chris Angelico amongst others and has failed dismally so why should you be any different? I've taken a different approach. I've put the contract out to tender and hereby give you the winners http://www.mudefordwoodcommunitycentre.co.uk/playgroup-and-tiny-tots/ Part of the rationale is that they're literally 100 yards from my front door so communicating with them effectively should be extremely easy. This will be particularly useful when it comes down to debugging such difficult issues as "> TypeError: 'NoneType' object is not iterable". I'm looking forward to working in partnership with them and am convinced that within a few days all of Nikos' problems will have been solved. -- Python is the second best programming language in the world. But the best has yet to be invented. Christian Tismer Mark Lawrence -- https://mail.python.org/mailman/listinfo/python-list
Re: Help me with this code PLEASE
In Nick the Gr33k writes: > IAM STRUGGLING WITH IT 2 DAYS NOW AND I CANNOT GET IT TO WORK. > ALL I WANT IT TO DO IS JUST > 1. RETRIEVE 3 COLUMNS THAT CONSIST OF 3 LONG STRINGS > 2. CONVERT LONG STRINGS TO LISTS > 3. ADD SOME CURRENT VALUES TO THOSE LISTS > 4. CONVERT FROM LISTS TO LONG STRINGS SO I CAN STORE SUCCESSFULLY LIST > PYTHON DATATYPE TO MYSQL SCALAR STRING. > EVERYHTIGN I TRIED FAILED. How did it fail? Error message? No results at all? Different results than you wanted? If so, how did they differ? -- John Gordon Imagine what it must be like for a real medical doctor to gor...@panix.comwatch 'House', or a real serial killer to watch 'Dexter'. -- https://mail.python.org/mailman/listinfo/python-list
Re: Help me with this code PLEASE
On Tue, 05 Nov 2013 20:09:42 +0200, Nick the Gr33k wrote:
> Denis, i have already provided my code trying to do what i need and i
> need some commendation on how to make it work.
Nick, you're obviously trying to code way above your abilities.
If you want me to write your code, you will have to pay my day rate, and
you can't afford it. If you could afford it, you'd be paying someone
competent already.
Here, have a code example, this works, although the formatting might get
broken. The database "ntg1" has a single table called str_idx defined as
follows:
create table idx_str ( idx int primary key, str varchar[1024] );
#!/usr/bin/python
import random
import sqlite3
def make_list( length ):
l = []
if ( length < 1 ):
return l
for count in range( 0, length ):
s = '';
for i in range( 1, random.randrange( 4, 12 ) ):
c = chr( random.randrange( 97, 123 ) )
s += c
l.append( s )
return l
def list_to_string( l ):
return "|".join( l )
def string_to_list( s ):
return s.split( "|" )
l1 = make_list( 10 )
print "l1 -> ", l1
s = list_to_string( l1 )
print "s -> ", s
l2 = string_to_list( s )
print "l2 -> ", l2
print "l1 == l2 -> ", l2 == l1
l2 = make_list( 10 )
l3 = make_list( 10 )
l4 = make_list( 10 )
print "Original Lists"
print "l1 -> ", l1
print "l2 -> ", l2
print "l3 -> ", l3
print "l4 -> ", l4
conn = sqlite3.connect( "ntg1" )
cur = conn.cursor()
cur.execute( "delete from idx_str where idx is not null" )
cur.execute(
"insert into idx_str values ( 1, '{0}' )".format(
list_to_string( l1 ) ) )
cur.execute(
"insert into idx_str values ( 2, '{0}' )".format(
list_to_string( l2 ) ) )
cur.execute(
"insert into idx_str values ( 3, '{0}' )".format(
list_to_string( l3 ) ) )
cur.execute(
"insert into idx_str values ( 4, '{0}' )".format(
list_to_string( l4 ) ) )
conn.commit()
conn.close()
print "Lists now in DB"
print "Reading 1 record at a time"
conn2 = sqlite3.connect( "ntg1" )
cur2 = conn2.cursor()
cur2.execute( "select * from idx_str where idx = 1" );
row = cur2.fetchone()
print "stored 1 -> ", row[ 1 ]
print "l1 -> ", string_to_list( row[ 1 ] )
cur2.execute( "select * from idx_str where idx = 2" );
row = cur2.fetchone()
print "stored 2 -> ", row[ 1 ]
print "l2 -> ", string_to_list( row[ 1 ] )
cur2.execute( "select * from idx_str where idx = 3" );
row = cur2.fetchone()
print "stored 3 -> ", row[ 1 ]
print "l3 -> ", string_to_list( row[ 1 ] )
cur2.execute( "select * from idx_str where idx = 4" );
row = cur2.fetchone()
print "stored 4 -> ", row[ 1 ]
print "l4 -> ", string_to_list( row[ 1 ] )
conn2.close()
print "Reading all records at once"
conn3 = sqlite3.connect( "ntg1" )
cur3 = conn3.cursor()
cur3.execute( "select * from idx_str" );
row = cur3.fetchone()
while not row == None:
print "stored ", row[ 0 ], " -> ", row[ 1 ]
print "list ", row[ 0 ], " -> ", string_to_list( row[ 1 ] )
row = cur3.fetchone()
conn3.close()
One thing you haven't considered, what happens if a user has so many
downloads in his list that the converted list doesn't fit in the declared
string column width in your database?
--
Denis McMahon, denismfmcma...@gmail.com
--
https://mail.python.org/mailman/listinfo/python-list
Re: Help me with this code PLEASE
On Tue, Nov 5, 2013 at 1:11 PM, Tobiah wrote: > All this problem arises because MySQL's hasn't got a datatype able to store > an array of elements, a list. > > Um, yes it does. It's called a table. > -- > https://mail.python.org/mailman/listinfo/python-list Perhaps we are splitting hairs, but a relational database will let you stuff any text you want in a text field, but First Normal Form is a necessary (and not complete) requirement (from wikipedia) First normal form (1NF) is a property of a relation in a relational database. A relation is in first normal form if the domain of each attribute contains only atomic values, and the value of each attribute contains only a single value from that domain.[1] If you don't have a single thing in a field, you can't search or sort it or filter by its value with sql. Since those are very important properties of sql, not using 1nf is similar to tossing a whole warehouse of stuff in a warehouse without any sort of organization for where different things are to be put, and therefore, where they can be found. If you don't have first normal form data, you are misusing a relational database. If you don't want to learn about relational databases and what they can do to help you construct software that solves interesting problems, then perhaps you are not curious enough to ever become competent in the field. That said, sql is a different beast than is python or php or any procedural (or oops) language. Just like writing HTML and CSS is something that people who write computer programs for the web might do, its a total shift in thinking from writing python. There is no rule that a person must be a computer programmer, but if a person wants to be a competent and successful computer programmer, one must learn from the evolving understanding of the last 50 years or so. Its a craft of understanding how to divide impossibly large problems into understandable pieces -- using the best tools for each piece. You may say this is just one person's opinion -- but then again, I'm not the one screaming in all caps about the same several problems over and over for the last year or more on this list. The results show no more understanding or growth in skills, and an attitude that never shows a glimmer of interest in learning. -- Joel Goldstick http://joelgoldstick.com -- https://mail.python.org/mailman/listinfo/python-list
Re: Help me with this code PLEASE
All this problem arises because MySQL's hasn't got a datatype able to store an array of elements, a list. Um, yes it does. It's called a table. -- https://mail.python.org/mailman/listinfo/python-list
Re: Help me with this code PLEASE
Στις 5/11/2013 8:02 μμ, ο/η Denis McMahon έγραψε: On Tue, 05 Nov 2013 19:06:25 +0200, Nick the Gr33k wrote: IAM STRUGGLING WITH IT 2 DAYS NOW AND I CANNOT GET IT TO WORK. Try starting with something simple. The following is a step by step guide to working out how you need to do this. Follow all the steps. Do not skip any steps. Each stage builds on the previous code. Write python code to create a list of strings and print out the elements of the list. This just needs to generate a list of n entries of m characters in length of random character data. Write python code to concatenate a list of strings into some longer string using a separator and print out the long string. Now add some python code to split the long string into a list based on the separator, and print out the list elements. Once you have this code working, make a test table with a single string column and an integer index field in a test database. Now this is starting to push the boundaries of your abilities, but write code to create two lists, and store them with indexes 1 and 2 respectively. Now, and this is really really going to tax you, write some more code that will first retrieve the string for index 1, convert it back into a list, and display the list contents, then do the same for list 2, then retrieve all the data from the db and reproduce each list in turn. Then you might be ready to try coding what you're trying to code. -- Denis, i have already provided my code trying to do what i need and i need some commendation on how to make it work. O even better an rdbms than allows complex data such as tuples, lists, dicts to be saved into the db as they are so i dont have to cobvet back and forth each time. -- https://mail.python.org/mailman/listinfo/python-list
Re: Help me with this code PLEASE
On Tue, 05 Nov 2013 19:06:25 +0200, Nick the Gr33k wrote: > IAM STRUGGLING WITH IT 2 DAYS NOW AND I CANNOT GET IT TO WORK. Try starting with something simple. The following is a step by step guide to working out how you need to do this. Follow all the steps. Do not skip any steps. Each stage builds on the previous code. Write python code to create a list of strings and print out the elements of the list. This just needs to generate a list of n entries of m characters in length of random character data. Write python code to concatenate a list of strings into some longer string using a separator and print out the long string. Now add some python code to split the long string into a list based on the separator, and print out the list elements. Once you have this code working, make a test table with a single string column and an integer index field in a test database. Now this is starting to push the boundaries of your abilities, but write code to create two lists, and store them with indexes 1 and 2 respectively. Now, and this is really really going to tax you, write some more code that will first retrieve the string for index 1, convert it back into a list, and display the list contents, then do the same for list 2, then retrieve all the data from the db and reproduce each list in turn. Then you might be ready to try coding what you're trying to code. -- Denis McMahon, denismfmcma...@gmail.com -- https://mail.python.org/mailman/listinfo/python-list
Re: Help me with this code PLEASE
Στις 5/11/2013 7:41 μμ, ο/η Steven D'Aprano έγραψε: On Tue, 05 Nov 2013 19:06:25 +0200, Nick the Gr33k wrote: ALL I WANT IT TO DO IS JUST 1. RETRIEVE 3 COLUMNS THAT CONSIST OF 3 LONG STRINGS 2. CONVERT LONG STRINGS TO LISTS 3. ADD SOME CURRENT VALUES TO THOSE LISTS 4. CONVERT FROM LISTS TO LONG STRINGS SO I CAN STORE SUCCESSFULLY LIST PYTHON DATATYPE TO MYSQL SCALAR STRING. You cannot do this with Python. You should use a better language more suited to you. Try this: http://php.net/manual/en/tutorial.php I hope that you will be much happier with this, since you are struggling to get Python to work the way you want it to. -- Steven, i want switch to php, i uses to start with php, then perl and now i ended up with python. All this problem arises because MySQL's hasn't got a datatype able to store an array of elements, a list. Is there some other database, sql connector i can use except 'pymysql' that supports a "collection" record type? postgresql or somethign similar? If it does i will switch to that and avoid these tedius convertions from long strings => list and backwise. Somehting that can just take Python's datatypes 'list' or 'tuple' or 'dict' as tehy are and just store them into the database convertionless. -- https://mail.python.org/mailman/listinfo/python-list
Re: Help me with this code PLEASE
Op 05-11-13 18:41, Steven D'Aprano schreef: > On Tue, 05 Nov 2013 19:06:25 +0200, Nick the Gr33k wrote: > >> ALL I WANT IT TO DO IS JUST >> >> 1. RETRIEVE 3 COLUMNS THAT CONSIST OF 3 LONG STRINGS 2. CONVERT LONG >> STRINGS TO LISTS >> 3. ADD SOME CURRENT VALUES TO THOSE LISTS 4. CONVERT FROM LISTS TO LONG >> STRINGS SO I CAN STORE SUCCESSFULLY LIST PYTHON DATATYPE TO MYSQL SCALAR >> STRING. > > > You cannot do this with Python. You should use a better language more > suited to you. Try this: > > http://php.net/manual/en/tutorial.php > > > I hope that you will be much happier with this, since you are struggling > to get Python to work the way you want it to. Steve, what went on in your mind? If Nikos follows you advise he will probably come here with all kinds of php questions. -- Antoon Pardon -- https://mail.python.org/mailman/listinfo/python-list
Re: Help me with this code PLEASE
On Tue, 05 Nov 2013 19:06:25 +0200, Nick the Gr33k wrote: > ALL I WANT IT TO DO IS JUST > > 1. RETRIEVE 3 COLUMNS THAT CONSIST OF 3 LONG STRINGS 2. CONVERT LONG > STRINGS TO LISTS > 3. ADD SOME CURRENT VALUES TO THOSE LISTS 4. CONVERT FROM LISTS TO LONG > STRINGS SO I CAN STORE SUCCESSFULLY LIST PYTHON DATATYPE TO MYSQL SCALAR > STRING. You cannot do this with Python. You should use a better language more suited to you. Try this: http://php.net/manual/en/tutorial.php I hope that you will be much happier with this, since you are struggling to get Python to work the way you want it to. -- Steven -- https://mail.python.org/mailman/listinfo/python-list
Re: Help me with this code PLEASE
EVERYHTIGN I TRIED FAILED. Maybe try some of the advice you have been given instead? -- https://mail.python.org/mailman/listinfo/python-list
Re: Help me with this code PLEASE
> = > > IAM STRUGGLING WITH IT 2 DAYS NOW AND I CANNOT GET IT TO WORK. > > ALL I WANT IT TO DO IS JUST > > 1. RETRIEVE 3 COLUMNS THAT CONSIST OF 3 LONG STRINGS > 2. CONVERT LONG STRINGS TO LISTS > 3. ADD SOME CURRENT VALUES TO THOSE LISTS > 4. CONVERT FROM LISTS TO LONG STRINGS SO I CAN STORE SUCCESSFULLY LIST PYTHON > DATATYPE TO MYSQL SCALAR STRING. > > EVERYHTIGN I TRIED FAILED. Don't start a new thread, where you just ask the same question, you already asked before. The answer will not be different just because you started a new thread. Did you already read the documentation of fetchone? -- Antoon Pardon -- https://mail.python.org/mailman/listinfo/python-list
Help me with this code PLEASE
==
# fetch those columns that act as lists but are stored as
strings
cur.execute('''SELECT refs, visits, downloads FROM visitors WHERE
counterID = %s and host = %s''', (cID, host) )
data = cur.fetchone()
ref = visit = download = []
if cur.rowcount:
# unpack data into variables
(ref, visit, download) = data
# retrieve long strings and convert them into lists
respectively
ref = ref.split()
visit = visit.split()
download = download.split()
else:
# initiate these values
ref = ref
visit = lastvisit
download = ''
refs = visits = downloads = []
# add current values to each list respectively
refs.append( ref )
visits.append( visit )
downloads.append( download )
# convert lists back to longstrings
refs = ', '.join( refs )
visits = ', '.join( visits )
downloads = ', '.join( downloads )
# save this visit as an entry into database
cur.execute('''INSERT INTO visitors (counterID, refs, host, city,
useros, browser, visits, downloads) VALUES (%s, %s, %s, %s, %s, %s, %s, %s)
ON DUPLICATE KEY UPDATE refs = %s, visits = %s, hits = hits + 1,
downloads = %s''',
(cID, refs, host, city, useros, browser, visits, downloads, refs,
visits, downloads) )
=
IAM STRUGGLING WITH IT 2 DAYS NOW AND I CANNOT GET IT TO WORK.
ALL I WANT IT TO DO IS JUST
1. RETRIEVE 3 COLUMNS THAT CONSIST OF 3 LONG STRINGS
2. CONVERT LONG STRINGS TO LISTS
3. ADD SOME CURRENT VALUES TO THOSE LISTS
4. CONVERT FROM LISTS TO LONG STRINGS SO I CAN STORE SUCCESSFULLY LIST
PYTHON DATATYPE TO MYSQL SCALAR STRING.
EVERYHTIGN I TRIED FAILED.
--
https://mail.python.org/mailman/listinfo/python-list
Re: pls help me with this prog
On Friday, October 19, 2012 4:40:42 PM UTC+8, inshu chauhan wrote: > in this prog I have written a code to calculate teh centre of a given 3D > data.. > > > > but i want to calculate it for every 3 points not the whole data, but > > instead of giving me centre for every 3 data the prog is printing the > > centre 3 times... > > > > import cv > > from math import floor, sqrt, ceil > > from numpy import array, dot, subtract, add, linalg as lin > > > > > > > > > > def CalcCentre(data): > > centre = array([0,0,0]) > > count = 0 > > n = 0 > > for p in data[n:n+3]: > > centre = add(centre, array(p[:3])) > > count += 1 > > centre = dot(1./count, centre) > > return centre > > n += 1 > > def ReadPointCloud(filename): > > f = open(filename) > > result = [] > > for l in f: > > sp = l.split() > > t = tuple(map(float, sp[1:4])) > > result.append(t) > > return result > > > > def main (data): > > > > > > j = 0 > > for i in data[:3]: > > while j != 3: > > centre = CalcCentre(data) > > j += 1 > > print centre > > > > > > if __name__ == '__main__': > > data = ReadPointCloud(r'Z:\data\NEHreflectance_Scanner 1_part.txt') > > > > main(data) > > > > > > > > > > PLS HELP # assume data is a list of 3 n numbers, n!=0 n3=data.length() n=n/3 x=sum(data[0:n3:3])/n y=sum(data[1:n3:3])/n z=sum(data[2:n3:3])/n #(x,y,z) -- http://mail.python.org/mailman/listinfo/python-list
Re: pls help me with this prog
inshu chauhan wrote: > >but i want to calculate it for every 3 points not the whole data, but >instead of giving me centre for every 3 data the prog is printing the >centre 3 times... > >def main (data): >j = 0 >for i in data[:3]: >while j != 3: > centre = CalcCentre(data) > j += 1 > print centre This loop doesn't do what you think it does. Think about the problem you have to solve. You have a set of data. You want to operate on the whole set, 3 points at a time. What this loop does is grab the first three points (only), then calculates the center on the entire list three times. You want something like: # As long as there is data in the list: while data: # Split the list into two parts: first 3 and the rest. first3, data = data[3:],data[3:] # Operate on the first three. print CalcCenter( first3 ) To make it a little more resilient, you might make sure that len(data) is a multiple of 3, or at least stop when it is shorter than 3. To be more clever, you can write a function that returns 3 at a time: def N_at_a_time( iter, n ): while len(iter) >= n: yield iter[:n] iter = iter[n:] Now you can do this: def main(data): for first3 in N_at_a_time(data, 3): print CalcCenter(first3) -- Tim Roberts, t...@probo.com Providenza & Boekelheide, Inc. -- http://mail.python.org/mailman/listinfo/python-list
Re: pls help me with this prog
Dont know what your code does/tries to do. Anyway some points: On Oct 19, 1:40 pm, inshu chauhan wrote: > in this prog I have written a code to calculate teh centre of a given 3D > data.. > > but i want to calculate it for every 3 points not the whole data, but > instead of giving me centre for every 3 data the prog is printing the > centre 3 times... > > import cv > from math import floor, sqrt, ceil > from numpy import array, dot, subtract, add, linalg as lin > > def CalcCentre(data): > centre = array([0,0,0]) > count = 0 > n = 0 > for p in data[n:n+3]: > centre = add(centre, array(p[:3])) > count += 1 > centre = dot(1./count, centre) > return centre > n += 1 The return makes the for iterate only once And n += 1 will never be reached >t = tuple(map(float, sp[1:4])) drops the sp[0] element. -- http://mail.python.org/mailman/listinfo/python-list
pls help me with this prog
in this prog I have written a code to calculate teh centre of a given 3D data.. but i want to calculate it for every 3 points not the whole data, but instead of giving me centre for every 3 data the prog is printing the centre 3 times... import cv from math import floor, sqrt, ceil from numpy import array, dot, subtract, add, linalg as lin def CalcCentre(data): centre = array([0,0,0]) count = 0 n = 0 for p in data[n:n+3]: centre = add(centre, array(p[:3])) count += 1 centre = dot(1./count, centre) return centre n += 1 def ReadPointCloud(filename): f = open(filename) result = [] for l in f: sp = l.split() t = tuple(map(float, sp[1:4])) result.append(t) return result def main (data): j = 0 for i in data[:3]: while j != 3: centre = CalcCentre(data) j += 1 print centre if __name__ == '__main__': data = ReadPointCloud(r'Z:\data\NEHreflectance_Scanner 1_part.txt') main(data) PLS HELP -- http://mail.python.org/mailman/listinfo/python-list
Re: PLEASE HELP ME WITH THIS ASSIGNMENT...PLEASE....
Daniel Fetchinson a écrit : Thanking you, Ms. Vaidehi Pawar How much do you pay? How much do you ask for cheers Ms. Vaidehi I was just kidding. But if you seriously need people to do this kind of job it's better to post the amount you are willing to pay otherwise nobody will take it seriously. If the OP seriously need people to do his schoolwork for him, then he'd better try to learn something else. Cheating is not a solution. -- http://mail.python.org/mailman/listinfo/python-list
Re: PLEASE HELP ME WITH THIS ASSIGNMENT...PLEASE....
> > I find it impossible to take anyone asking others to do their school > work for them seriously no matter how or what they are willing to pay. > Exactly, and writing the subject of the post in all capitals doesn't help either... Almar -- http://mail.python.org/mailman/listinfo/python-list
Re: PLEASE HELP ME WITH THIS ASSIGNMENT...PLEASE....
On Thu, Sep 11, 2008 at 12:02 PM, Daniel Fetchinson <[EMAIL PROTECTED]> wrote: > > >>> Thanking you, >>> >>> Ms. Vaidehi Pawar >> >> How much do you pay? >> >>> How much do you ask for >>> >>> cheers >>> Ms. Vaidehi > > I was just kidding. But if you seriously need people to do this kind > of job it's better to post the amount you are willing to pay otherwise > nobody will take it seriously. > > Cheers, > Daniel > -- > Psss, psss, put it down! - http://www.cafepress.com/putitdown > -- > http://mail.python.org/mailman/listinfo/python-list > I find it impossible to take anyone asking others to do their school work for them seriously no matter how or what they are willing to pay. -- Stand Fast, tjg. [Timothy Grant] -- http://mail.python.org/mailman/listinfo/python-list
Re: PLEASE HELP ME WITH THIS ASSIGNMENT...PLEASE....
>> Thanking you, >> >> Ms. Vaidehi Pawar > > How much do you pay? > >> How much do you ask for >> >> cheers >> Ms. Vaidehi I was just kidding. But if you seriously need people to do this kind of job it's better to post the amount you are willing to pay otherwise nobody will take it seriously. Cheers, Daniel -- Psss, psss, put it down! - http://www.cafepress.com/putitdown -- http://mail.python.org/mailman/listinfo/python-list
Re: PLEASE HELP ME WITH THIS ASSIGNMENT...PLEASE....
On Sep 10, 3:33 pm, "Daniel Fetchinson" <[EMAIL PROTECTED]> wrote: > > I know I'm to late to ask you for helpbut please help me out..I > > am really new to unix and dont know how to finish this assignment on > > time.proff. said he will be using MOSS to detect whether I > > downloaded the code..please help me.. > > > email me : [EMAIL PROTECTED] > > > Assignment 1 > > Processes, Inter-Process Communication, and Concurrency > > Due September 13th midnight > > Summary > > In > > this assignment, you will create two versions of a simple multi-process > > game : one without and another with inter-process synchronization. You > > will also measure the relative performance of the two versions of your > > multi-process game. > > Objectives > > > * Learn how to create and terminate processes. > > * Learn use of inter-process communication using shared memory, > > semaphores, signals, etc. > > * Learn the basic workings of CPU scheduling code in Linux. > > > Part A: Multi-Process Game of Turns > > > In > > this part, you are asked to write a simple program that takes two > > command-line arguments P and N. The main process creates P other child > > processes, waits for all of them to complete, and then exits. All the > > child processes form one logical ring among each other. (In rest of the > > description, the term "process" refers to a "child process".) For > > example, if the processes are numbered 1 to P, then > > > * The next neighbor of process 1 is process 2, > > * The next neighbor of process i is process i+1 for all i < P , and > > * The next neighbor of process P is process 1, which completes a ring > > among the processes. > > > Assume > > that a shared integer variable, called turn, identifies the number of > > the processes whose turn it is at any instant. A second process-local > > variable in each process, called me, identifies the identity of each > > process (i.e. each process stores its own identity in a per-process > > local variable me). A third per-process local variable, called next, > > identifies the next process in the ring. > > > The processes > > sequentially pass the turns among each other in the logical ring. When > > each process gets its turn, it increments another shared variable > > called counter. The pseudo-code within each process for passing turns > > might look something as follows. (Note: Replace turn and counter below > > with appropriate ways of accessing data within shared memory regions). > > > while(turn != me ) > > /* do nothing - just busy loop*/ ; > > > /* got my turn - increment counter */ > > counter = counter + 1; > > > /* give the turn to next process */ > > turn = next; > > > The program terminates when the each process has received N turns. > > > In the above description, several programming details have been omitted for > > you to figure out. This includes > > > * Creating P child processes from main process. > > * Constructing the logical ring among child processes. > > o Initializing each child process's identity in the me variable. > > o Initializing each child process' next neighbor in the next > > variable. > > * Initializing the shared memory region and the shared data values. > > * Have the main process wait for child processes to complete N turns > > before exiting. > > > Part B: More Efficient Game of Turns > > > You > > might notice that the program you wrote in Part A is inefficient > > because each process busy loops till the CPU scheduler kicks it out > > (after its time-slice is over) and allows another process to execute > > and make progress. (Does the program in Part A have a race condition? > > Why or why not?) > > > What we ideally want is that each process > > should be given control of the CPU only when it is that process' turn. > > Modify the program you wrote in Part A (using appropriate > > synchronization mechanisms) such that each process gets to run (i.e., > > gets control of the CPU) only when it is that process's turn, and at no > > other time. > > > Again, you would need to work out the programming details of how and where > > to use inter-process synchronization. > > Part C: Profiling the Game of Turns > > > In > > this part, you are asked to write user-level profiling code in order to > > measure the performance of the two versions of programs you wrote in > > Part A and Part B. Use a combination of gettimeofday() system call and > > inter-process synchronization to measure (1) the average hand-over time > > between two consecutive processes in the ring and (b) the total > > execution time to complete N turns. Plot the measured values as graphs > > when varying number of processes P and number of turns N. Explain the > > results you obtain. > > Submission Guidelines > > > Thanking you, > > > Ms. Vaidehi Pawar > > How much do you pay? > > Cheers, > Daniel > -- > Psss, psss, put it down! -http://www.cafepress.com/putitdown Maybe. I
Re: PLEASE HELP ME WITH THIS ASSIGNMENT...PLEASE....
> I know I'm to late to ask you for helpbut please help me out..I > am really new to unix and dont know how to finish this assignment on > time.proff. said he will be using MOSS to detect whether I > downloaded the code..please help me.. > > email me : [EMAIL PROTECTED] > > Assignment 1 > Processes, Inter-Process Communication, and Concurrency > Due September 13th midnight > Summary > In > this assignment, you will create two versions of a simple multi-process > game : one without and another with inter-process synchronization. You > will also measure the relative performance of the two versions of your > multi-process game. > Objectives > > * Learn how to create and terminate processes. > * Learn use of inter-process communication using shared memory, > semaphores, signals, etc. > * Learn the basic workings of CPU scheduling code in Linux. > > Part A: Multi-Process Game of Turns > > In > this part, you are asked to write a simple program that takes two > command-line arguments P and N. The main process creates P other child > processes, waits for all of them to complete, and then exits. All the > child processes form one logical ring among each other. (In rest of the > description, the term "process" refers to a "child process".) For > example, if the processes are numbered 1 to P, then > > * The next neighbor of process 1 is process 2, > * The next neighbor of process i is process i+1 for all i < P , and > * The next neighbor of process P is process 1, which completes a ring > among the processes. > > Assume > that a shared integer variable, called turn, identifies the number of > the processes whose turn it is at any instant. A second process-local > variable in each process, called me, identifies the identity of each > process (i.e. each process stores its own identity in a per-process > local variable me). A third per-process local variable, called next, > identifies the next process in the ring. > > The processes > sequentially pass the turns among each other in the logical ring. When > each process gets its turn, it increments another shared variable > called counter. The pseudo-code within each process for passing turns > might look something as follows. (Note: Replace turn and counter below > with appropriate ways of accessing data within shared memory regions). > > while(turn != me ) > /* do nothing - just busy loop*/ ; > > /* got my turn - increment counter */ > counter = counter + 1; > > /* give the turn to next process */ > turn = next; > > The program terminates when the each process has received N turns. > > In the above description, several programming details have been omitted for > you to figure out. This includes > > * Creating P child processes from main process. > * Constructing the logical ring among child processes. > o Initializing each child process's identity in the me variable. > o Initializing each child process' next neighbor in the next > variable. > * Initializing the shared memory region and the shared data values. > * Have the main process wait for child processes to complete N turns > before exiting. > > Part B: More Efficient Game of Turns > > You > might notice that the program you wrote in Part A is inefficient > because each process busy loops till the CPU scheduler kicks it out > (after its time-slice is over) and allows another process to execute > and make progress. (Does the program in Part A have a race condition? > Why or why not?) > > What we ideally want is that each process > should be given control of the CPU only when it is that process' turn. > Modify the program you wrote in Part A (using appropriate > synchronization mechanisms) such that each process gets to run (i.e., > gets control of the CPU) only when it is that process's turn, and at no > other time. > > Again, you would need to work out the programming details of how and where > to use inter-process synchronization. > Part C: Profiling the Game of Turns > > In > this part, you are asked to write user-level profiling code in order to > measure the performance of the two versions of programs you wrote in > Part A and Part B. Use a combination of gettimeofday() system call and > inter-process synchronization to measure (1) the average hand-over time > between two consecutive processes in the ring and (b) the total > execution time to complete N turns. Plot the measured values as graphs > when varying number of processes P and number of turns N. Explain the > results you obtain. > Submission Guidelines > > Thanking you, > > Ms. Vaidehi Pawar How much do you pay? Cheers, Daniel -- Psss, psss, put it down! - http://www.cafepress.com/putitdown -- http://mail.python.org/mailman/listinfo/python-list
PLEASE HELP ME WITH THIS ASSIGNMENT...PLEASE....
I know I'm to late to ask you for helpbut please help me out..I am really new to unix and dont know how to finish this assignment on time.proff. said he will be using MOSS to detect whether I downloaded the code..please help me.. email me : [EMAIL PROTECTED] Assignment 1 Processes, Inter-Process Communication, and Concurrency Due September 13th midnight Summary In this assignment, you will create two versions of a simple multi-process game : one without and another with inter-process synchronization. You will also measure the relative performance of the two versions of your multi-process game. Objectives * Learn how to create and terminate processes. * Learn use of inter-process communication using shared memory, semaphores, signals, etc. * Learn the basic workings of CPU scheduling code in Linux. Part A: Multi-Process Game of Turns In this part, you are asked to write a simple program that takes two command-line arguments P and N. The main process creates P other child processes, waits for all of them to complete, and then exits. All the child processes form one logical ring among each other. (In rest of the description, the term "process" refers to a "child process".) For example, if the processes are numbered 1 to P, then * The next neighbor of process 1 is process 2, * The next neighbor of process i is process i+1 for all i < P , and * The next neighbor of process P is process 1, which completes a ring among the processes. Assume that a shared integer variable, called turn, identifies the number of the processes whose turn it is at any instant. A second process-local variable in each process, called me, identifies the identity of each process (i.e. each process stores its own identity in a per-process local variable me). A third per-process local variable, called next, identifies the next process in the ring. The processes sequentially pass the turns among each other in the logical ring. When each process gets its turn, it increments another shared variable called counter. The pseudo-code within each process for passing turns might look something as follows. (Note: Replace turn and counter below with appropriate ways of accessing data within shared memory regions). while(turn != me ) /* do nothing - just busy loop*/ ; /* got my turn - increment counter */ counter = counter + 1; /* give the turn to next process */ turn = next; The program terminates when the each process has received N turns. In the above description, several programming details have been omitted for you to figure out. This includes * Creating P child processes from main process. * Constructing the logical ring among child processes. o Initializing each child process's identity in the me variable. o Initializing each child process' next neighbor in the next variable. * Initializing the shared memory region and the shared data values. * Have the main process wait for child processes to complete N turns before exiting. Part B: More Efficient Game of Turns You might notice that the program you wrote in Part A is inefficient because each process busy loops till the CPU scheduler kicks it out (after its time-slice is over) and allows another process to execute and make progress. (Does the program in Part A have a race condition? Why or why not?) What we ideally want is that each process should be given control of the CPU only when it is that process' turn. Modify the program you wrote in Part A (using appropriate synchronization mechanisms) such that each process gets to run (i.e., gets control of the CPU) only when it is that process's turn, and at no other time. Again, you would need to work out the programming details of how and where to use inter-process synchronization. Part C: Profiling the Game of Turns In this part, you are asked to write user-level profiling code in order to measure the performance of the two versions of programs you wrote in Part A and Part B. Use a combination of gettimeofday() system call and inter-process synchronization to measure (1) the average hand-over time between two consecutive processes in the ring and (b) the total execution time to complete N turns. Plot the measured values as graphs when varying number of processes P and number of turns N. Explain the results you obtain. Submission Guidelines Thanking you, Ms. Vaidehi Pawar Check out the all-new face of Yahoo! India. Go to http://in.yahoo.com/-- http://mail.python.org/mailman/listinfo/python-list
Re: Help me with this!!!
On Thu, 01 Feb 2007 08:53:55 -0800, Ravi Teja wrote: >> > > It search a text inside that hex value. >> > > It works perfecly on a txt file but if I open a binary file (.exe,.bin >> > > ecc...) with the same value it wont work, why? >> > > Please help! >> >> > Because the pattern isn't in the file, perhaps. >> >> This pattern IS in the file (I made it and I double check with an hex >> editor). >> It display the file correcltly (print line) but... > > No! Peter is right. Regular expressions match ASCII representation of > data, not hex. In simple terms, do you see your pattern when you open > the file in notepad (or other text editor)? You do not use regex to > search binary files. I don't see why not. >>> pattern = "NULL\0" >>> source = "\0\01\02-more-bytes-here-NULL\0-more-bytes" >>> m = re.search(pattern, source) >>> m.group() 'NULL\x00' >>> m.span() (20, 25) Here's the Original Poster's code again: regex = re.compile(r"(?si)(\x8B\xF0\x85\xF6)(?P.*) (\xC6\x44\x24)",re.IGNORECASE) file = open(fileName, "rb") for line in file: if (match): print line file.close() I suggest that the reason it doesn't work is because he never actually uses the regex. Presumably the name "match" was assigned somewhere else to a false value, and so the code simply walks through the file doing nothing. -- Steven D'Aprano -- http://mail.python.org/mailman/listinfo/python-list
Re: Help me with this!!!
> > > It search a text inside that hex value. > > > It works perfecly on a txt file but if I open a binary file (.exe,.bin > > > ecc...) with the same value it wont work, why? > > > Please help! > > > Because the pattern isn't in the file, perhaps. > > This pattern IS in the file (I made it and I double check with an hex > editor). > It display the file correcltly (print line) but... No! Peter is right. Regular expressions match ASCII representation of data, not hex. In simple terms, do you see your pattern when you open the file in notepad (or other text editor)? You do not use regex to search binary files. Ravi Teja. -- http://mail.python.org/mailman/listinfo/python-list
Re: Help me with this!!!
On Feb 1, 4:21 am, "TOXiC" <[EMAIL PROTECTED]> wrote:
> Hi all, I've this code:
>
> regex = re.compile(r"(?si)(\x8B\xF0\x85\xF6)(?P.*)
> (\xC6\x44\x24)",re.IGNORECASE)
> file = open(fileName, "rb")
> for line in file:
> if (match):
> print line
> file.close()
>
> It search a text inside that hex value.
> It works perfecly on a txt file but if I open a binary file (.exe,.bin
> ecc...) with the same value it wont work, why?
> Please help!
Where do you assign the value of 'match'? Perhaps you are missing a
line such as "match=regex.match(line)" or "match=regex.search(line)"?
Perhaps this is why Peter Otten says that this code can't possibly be
the code that works for text files?
What is the significance of "for line in file" when file is opened in
binary mode? Are EOLs properly interpreted in binary mode? ('file'
is not the best variable name, by the way, as it masks Python's built-
in file. How about "file_", or "inputfile", or "fileToBeSearched"?)
-- Paul
--
http://mail.python.org/mailman/listinfo/python-list
Re: Help me with this!!!
Peter Otten ha scritto: > TOXiC wrote: > > > Hi all, I've this code: > > No you don't. > ! > > regex = re.compile(r"(?si)(\x8B\xF0\x85\xF6)(?P.*) > > (\xC6\x44\x24)",re.IGNORECASE) > > file = open(fileName, "rb") > > for line in file: > > if (match): > > print line > > file.close() > > > > It search a text inside that hex value. > > It works perfecly on a txt file but if I open a binary file (.exe,.bin > > ecc...) with the same value it wont work, why? > > Please help! > > Because the pattern isn't in the file, perhaps. > This pattern IS in the file (I made it and I double check with an hex editor). It display the file correcltly (print line) but... -- http://mail.python.org/mailman/listinfo/python-list
Re: Help me with this!!!
TOXiC wrote: > Hi all, I've this code: No you don't. > regex = re.compile(r"(?si)(\x8B\xF0\x85\xF6)(?P.*) > (\xC6\x44\x24)",re.IGNORECASE) > file = open(fileName, "rb") > for line in file: > if (match): > print line > file.close() > > It search a text inside that hex value. > It works perfecly on a txt file but if I open a binary file (.exe,.bin > ecc...) with the same value it wont work, why? > Please help! Because the pattern isn't in the file, perhaps. Peter -- http://mail.python.org/mailman/listinfo/python-list
Help me with this!!!
Hi all, I've this code: regex = re.compile(r"(?si)(\x8B\xF0\x85\xF6)(?P.*) (\xC6\x44\x24)",re.IGNORECASE) file = open(fileName, "rb") for line in file: if (match): print line file.close() It search a text inside that hex value. It works perfecly on a txt file but if I open a binary file (.exe,.bin ecc...) with the same value it wont work, why? Please help! -- http://mail.python.org/mailman/listinfo/python-list
