Re: [Tutor] I can't believe this needs to be this complex
Dick Moores [EMAIL PROTECTED] wrote code I time. What's an example of code that would have System be greater than zero? And what's the distinction between User and System? (I'm using Win XP, if that's relevant.) It may be that XP doesn't report System time. Well, here's one that reads in the text of Dickens' _Little Dorrit_ and returns the word count: IPython CPU timings (estimated): Total runs performed: 10 Times : Total Per run User : 5.94446752311 s, 0.594446752311 s. System:0.0 s,0.0 s. I would definitely have expected some system time there. This one is a Gui that has an Exit button. I called it and then hit the button: IPython CPU timings (estimated): User : 10.5294301371 s. System:0.0 s. That suggests that it is counting elapsed time as user time in which case I'm not sure how it counts system time. It may be an XP issue. Anyone got different results under Linux/MacOS? Alan G. ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Developing Macro: Is it possible in Python?
Federo [EMAIL PROTECTED] wrote Is it possible to do macro with Python? Macro means different things in different context. Macro should be able to click on given x,y screen location (one click, double click), drag scroll bar up / down etc.. It seems that you are referring to simulating user actions. The answer then is yes its possible but not trivial. You can use the low level Windows API to send messages to windows simulating mouse clicks etc. But it will usually require monitoring the messages first using a program like Windows Spy. The result is extremely fragile in that any change in the windows environment can render your code useless. Is there any other way beside macro to control windows based application? If it supports COM then you can use COM objects to manipulate things directly. The winall package has support for COM or you can use the API directly via ctypes. I confess I tend to use VBScript for this kind of thing, IMHO it plays with Windows much more simply than Python. Alan G. ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Output never stops
David [EMAIL PROTECTED] wrote
the output never stops when I run this in a terminal
choice = raw_input(Enter the name Lary or Joan (-1 to quit): )
while choice != '-1':
person = {'Lary': 43,'Joan': 24}
if choice == 'Lary':
print Lary's age is:, person.get('Lary')
elif choice == 'Joan':
print Joan's age is:, person.get('Joan')
else:
print 'Bad Code'
You set choice outside the while loop then never change
it so the while test will always be true and loop forever.
You need to copy the raw_input line into the body of
the while loop to reset choice.
Also for good style you should move the person = {} line outside
the loop since you only want to set up the dictionary once,
not every time you execute the loop. The dictionary never
changes so recreating it every time is wasteful.
HTH,
--
Alan Gauld
Author of the Learn to Program web site
http://www.freenetpages.co.uk/hp/alan.gauld
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Re: [Tutor] I can't believe this needs to be this complex
At 01:00 AM 8/3/2008, Alan Gauld wrote: Dick Moores [EMAIL PROTECTED] wrote code I time. What's an example of code that would have System be greater than zero? And what's the distinction between User and System? (I'm using Win XP, if that's relevant.) It may be that XP doesn't report System time. Well, here's one that reads in the text of Dickens' _Little Dorrit_ and returns the word count: IPython CPU timings (estimated): Total runs performed: 10 Times : Total Per run User : 5.94446752311 s, 0.594446752311 s. System:0.0 s,0.0 s. I would definitely have expected some system time there. This one is a Gui that has an Exit button. I called it and then hit the button: IPython CPU timings (estimated): User : 10.5294301371 s. System:0.0 s. That suggests that it is counting elapsed time as user time in which case I'm not sure how it counts system time. It may be an XP issue. Anyone got different results under Linux/MacOS? _Little Dorrit_ is available in us-ascii at http://www.gutenberg.org/etext/963; _War and Peace_ at http://www.gutenberg.org/etext/2600. Dick ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] I can't believe this needs to be this complex
On Sun, Aug 3, 2008 at 4:00 AM, Alan Gauld [EMAIL PROTECTED] wrote: Dick Moores [EMAIL PROTECTED] wrote code I time. What's an example of code that would have System be greater than zero? And what's the distinction between User and System? (I'm using Win XP, if that's relevant.) It may be that XP doesn't report System time. From the IPython help for 'run': -t: print timing information at the end of the run. IPython will giveyou an estimated CPU time consumption for your script, which underUnix uses the resource module to avoid the wraparound problems oftime.clock(). Under Unix, an estimate of time spent on system tasksis also given (for Windows platforms this is reported as 0.0). Kent ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
[Tutor] Decimals 'not equal to themselves' (e.g. 0.2 equals 0.200000001)
I am very new to Python (I started learning it just yesterday), but I have encountered a problem. I want to make a simple script that calculates the n-th root of a given number (e.g. 4th root of 625--obviously five, but it's just an example :P), and because there is no nth-root function in Python I will do this with something like x**(1/n). However, with some, but not all, decimals, they do not seem to 'equal themselves'. This is probably a bad way of expressing what I mean, so I'll give an example: 0.5 0.5 0.25 0.25 0.125 0.125 0.2 0.20001 0.33 0.33002 As you can see, the last two decimals are very slightly inaccurate. However, it appears that when n in 1/n is a power of two, the decimal does not get 'thrown off'. How might I make Python recognise 0.2 as 0.2 and not 0.20001? This discrepancy is very minor, but it makes the whole n-th root calculator inaccurate. :\ ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] I can't believe this needs to be this complex
At 05:15 AM 8/3/2008, Kent Johnson wrote: On Sun, Aug 3, 2008 at 4:00 AM, Alan Gauld [EMAIL PROTECTED] wrote: Dick Moores [EMAIL PROTECTED] wrote code I time. What's an example of code that would have System be greater than zero? And what's the distinction between User and System? (I'm using Win XP, if that's relevant.) It may be that XP doesn't report System time. From the IPython help for 'run': -t: print timing information at the end of the run. IPython will giveyou an estimated CPU time consumption for your script, which underUnix uses the resource module to avoid the wraparound problems oftime.clock(). Under Unix, an estimate of time spent on system tasksis also given Thanks, Kent. RTFM! (for Windows platforms this is reported as 0.0). I wonder why it is reported for Windows at all? Dick ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Decimals 'not equal to themselves' (e.g. 0.2 equals 0.200000001)
CNiall wrote:
I want to make a simple script that calculates the n-th root of a given
number (e.g. 4th root of 625--obviously five, but it's just an example
:P), and because there is no nth-root function in Python I will do this
with something like x**(1/n).
Side note: of course there are python built-in ways to do that. You just
named one yourself:
In [6]: 625**(1.0/4)
Out[6]: 5.0
also:
In [9]: pow(625, 1.0/4)
Out[9]: 5.0
However, with some, but not all, decimals, they do not seem to 'equal
themselves'.
As you can see, the last two decimals are very slightly inaccurate.
However, it appears that when n in 1/n is a power of two, the decimal
does not get 'thrown off'. How might I make Python recognise 0.2 as 0.2
and not 0.20001?
You just can't store 0.1 as a binary floating point.
You might want to read:
http://www.network-theory.co.uk/docs/pytut/FloatingPointArithmeticIssuesandLimitations.html
http://www.network-theory.co.uk/docs/pytut/RepresentationError.html
The decimal module provides decimal floating point arithmetic:
http://docs.python.org/lib/module-decimal.html
like in:
In [1]: 0.2 * 2
Out[1]: 0.40002
In [2]: from decimal import Decimal
In [3]: Decimal('0.2') * 2
Out[3]: Decimal(0.4)
thomas
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Re: [Tutor] I can't believe this needs to be this complex
At 05:15 AM 8/3/2008, Kent Johnson wrote: On Sun, Aug 3, 2008 at 4:00 AM, Alan Gauld [EMAIL PROTECTED] wrote: Dick Moores [EMAIL PROTECTED] wrote code I time. What's an example of code that would have System be greater than zero? And what's the distinction between User and System? (I'm using Win XP, if that's relevant.) It may be that XP doesn't report System time. From the IPython help for 'run': -t: print timing information at the end of the run. IPython will giveyou an estimated CPU time consumption for your script, which underUnix uses the resource module to avoid the wraparound problems oftime.clock(). Under Unix, an estimate of time spent on system tasksis also given Thanks, Kent. RTFM! (for Windows platforms this is reported as 0.0). I wonder why it is reported for Windows at all? Dick ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Output never stops
Alan Gauld wrote:
David [EMAIL PROTECTED] wrote
the output never stops when I run this in a terminal
choice = raw_input(Enter the name Lary or Joan (-1 to quit): )
while choice != '-1': person = {'Lary': 43,'Joan': 24}
if choice == 'Lary':
print Lary's age is:, person.get('Lary')
elif choice == 'Joan':
print Joan's age is:, person.get('Joan')
else:
print 'Bad Code'
You set choice outside the while loop then never change it so the
while test will always be true and loop forever.
You need to copy the raw_input line into the body of the while loop to
reset choice.
Also for good style you should move the person = {} line outside the
loop since you only want to set up the dictionary once, not every time
you execute the loop. The dictionary never changes so recreating it
every time is wasteful.
HTH,
Thanks Alan, also your tutorial/book is a big help. I think I got it :)
#!/usr/bin/python
person = {'Lary':43,'Joan':24}
choice = 0
while choice != '-1':
if choice == '':
print You must enter Lary or Joan to continue! (-1 to quit):
choice = raw_input(
Who's age do want to know, Lary or Joan? (-1 to quit): )
if choice == 'Lary':
print Lary's age is:, person.get('Lary')
elif choice == 'Joan':
print Joan's age is:, person.get('Joan')
else:
print Goodbye!
--
Powered by Gentoo GNU/LINUX
http://www.linuxcrazy.com
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Re: [Tutor] Decimals 'not equal to themselves' (e.g. 0.2 equals 0.200000001)
On Sun, Aug 3, 2008 at 10:04 AM, CNiall [EMAIL PROTECTED] wrote: I want to make a simple script that calculates the n-th root of a given number (e.g. 4th root of 625--obviously five, but it's just an example :P), and because there is no nth-root function in Python I will do this with something like x**(1/n). However, with some, but not all, decimals, they do not seem to 'equal themselves'. This is probably a bad way of expressing what I mean, so I'll give an example: 0.125 0.2 0.20001 0.33 0.33002 As you can see, the last two decimals are very slightly inaccurate. However, it appears that when n in 1/n is a power of two, the decimal does not get 'thrown off'. How might I make Python recognise 0.2 as 0.2 and not 0.20001? This is a limitation of floaating point numbers. A discussion is here: http://docs.python.org/tut/node16.html Your root calculator can only find answers that are as accurate as the representation allows. Kent ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Decimals 'not equal to themselves' (e.g. 0.2 equals0.200000001)
CNiall [EMAIL PROTECTED] wrote However, with some, but not all, decimals, they do not seem to 'equal themselves'. This is probably a bad way of expressing what I mean, so I'll give an example: 0.5 0.5 0.2 0.20001 As you can see, the last two decimals are very slightly inaccurate. However, it appears that when n in 1/n is a power of two, the decimal does not get 'thrown off'. And that is the clue. Computers represent data as binary, ie powers of two. If a number cannot be expressed exactly as a power of two then a computer (any binary computer!) cannot represent the number exactly. It is the same in natural arithmetic where we use base 10. We cannot exactly represent numbers like 1/3 as a decimal number we have to approximate to 0. Likewise with 1/7 etc. In most cases the approximation is good enough and we just live with it. (But its not a good idea to use floating point numbers to represent money!). If you do need exact numbers you can use the decimal module which will do what you want but at the expense of adding complexity. How might I make Python recognise 0.2 as 0.2 and not 0.20001? Mostl;y it won;t matter, what you will want is to be able to print it as 0.2. You can do this in a number of ways but the most flexible is to use a format string: x = 0.2 print %6f % x 0.2000 The percent inside the string is a marker which is substituted by the value after the percent outside the string (ie x in this case) The number following the first % is the length of representation - 6 chars in this case. There are several other numbers and symbols you can use to coerce the representation to be as you wish - left/roight aligned, leading zeros, scientific notation etc Search the Python docs for format and you should find the details... The other thing to watch is when comparing float values. y = 1 - 0.8 y == x False e = 0.01 x-e y x+e True You can find out more about format stringsin the Simple Sequences topic of my tutorial. You can find out a little bit more about floating point numbers in the Raw Data topic of my tutorial under the heading Real Numbers. HTH, -- Alan Gauld Author of the Learn to Program web site http://www.freenetpages.co.uk/hp/alan.gauld ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Developing Macro: Is it possible in Python?
I have used pywinauto for such tasks in the past. http://pywinauto.openqa.org/ In my case, I used pywinauto to automate mouse clicks on a browser in order to auto-play a Flash game running in the browser. I had to use PIL to take screenshots and then process images to read the screen. -- Paul ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Developing Macro: Is it possible in Python?
Federo wrote: snip Above actions can be easily performed using Macro Scheduler. I am looking for possibility to do the same with Python? Hi Federo, I regularly combine Macro Scheduler with python by having my python code write mSched scripts. I find the combination of the two particularly adept at controlling legacy windows apps on current windows platforms. The main function accepts a command list and name, writes a .scp msched script file and invokes the mSched command with os.system. When I first considered how to approach this in about 2002, I looked at Mark Hammonds extensions and tried that, but it seemed to me at the time that the older apps simply didn't play nice and I fought harder to implement a pure python solution than the problem deserved. Now, it's easy to review the python created msched scripts and 'follow along' to catch the odd bug. mSched's capabilities have grown over that time as well and added some commands that make timing issues more predictable. Although, I admit I'm never actually in the mSched environment so I may well be doing things with python that are entirely doable in mSched. But, with python as glue I can control and coordinate as many disparate environments as the solution requires and it's mostly quick and easy. Emile ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Firstrade Authentication ...
On Sun, Aug 3, 2008 at 12:45 PM, Federo [EMAIL PROTECTED] wrote:
Jeff, Kent Hi!
If possible I would most appreciate to use mechanize approach Jeff suggested.
Python plagin: http://wwwsearch.sourceforge.net/mechanize/
This seems to get to the Thank you for applying for a Firstrade account. page:
import urllib2
import urllib
opener = urllib2.build_opener(urllib2.HTTPCookieProcessor())
urllib2.install_opener(opener)
f = opener.open('https://investor.firstrade.com/firstrade/login.do')
data = f.read()
f.close()
params = dict(username='janezfedero', password='kmet500', destination='')
params['login.x'] = 'Log+In'
params = urllib.urlencode(params)
f = opener.open('https://investor.firstrade.com/firstrade/login.do', params)
data = f.read()
f.close()
print(data)
Differences from your code:
- Does a GET on the login page - the session cookie is set here, not on the POST
- Includes all the form parameters
Kent
PS Please respond to the list, not to me personally.
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[Tutor] newbie: write ArcGIS lists to file?
Dear List, This is my first time on the list, and my first run at Python, please forgive my ignorance. I'm trying to use Python to access ArcGIS modules in order to perform the same task on multiple files in a folder. I'm able to access a set of files via: import arcgisscripting, string gp = arcgisscripting.create() gp.Workspace = E:/data rasterSelect = [] rasterList = gp.ListRasters(, tif) raster = rasterList.Next() while raster: if raster.endswith(_dt.tif): print raster rasterSelect.append(raster) raster = rasterList.Next() This produces a list of all the files I have in my folder. I need to begin producing .csv files of this list that I can access using other programs. Would someone be willing to post a few lines of code showing me how to write the list the code above creates to an external file? Gratefully, Zack ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Firstrade Authentication ...
Kent Johnson wrote: [snip] params = dict(username='janezfedero', password='kmet500', destination='') I hope this is a fake username password Regards, Patrick ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
[Tutor] Any Italian speakers?
I received this message which Google tells me is Italian but then only gives a partial translation... Can anyone help? --- voglio chiderti solo 1 cosa ... ma secondo te qualle e il miglior programma X programmare??? grazie ... da Cristian - Alan G. ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Output never stops
David [EMAIL PROTECTED] wrote
Thanks Alan, also your tutorial/book is a big help. I think I got it
:)
Close but not quite there yet.
choice = 0
while choice != '-1':
if choice == '':
print You must enter Lary or Joan to continue! (-1 to quit):
choice = raw_input(
Who's age do want to know, Lary or Joan? (-1 to quit):
)
if choice == 'Lary':
print Lary's age is:, person.get('Lary')
elif choice == 'Joan':
print Joan's age is:, person.get('Joan')
else:
print Goodbye!
Consider what happens if I enter a blank name.
You print Goodbye but then go round the loop again prompting
for another choice. You probably want the Goodbye to only
be printed if choice == '-1'?
And the test for the empty string should ptrobably be after
you ask for the input?
Also the normal way to access a dictionary value is to
use square brackets:
person['Lary']
get() does have the advantage that you can add a default
value that is returned if the key doesn't exist. But that's
not relevant in this case.
HTH,
--
Alan Gauld
Author of the Learn to Program web site
http://www.freenetpages.co.uk/hp/alan.gauld
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[Tutor] List elements as indices to another list
Hi, I have a simple matrix (nested list) defined as such: M = [[1, 2, 3], [4, 5, 6], [7, 8, 9]] I'm trying to come up with a different way of getting its, well, reverse antidiagonal, since the actual antidiagonal of M goes from M[0, N] to M[N, 0] according to http://planetmath.org/encyclopedia/AntiDiagonalMatrix.html: j = 0 for i in range(len(M)-1, -1, -1): print M[i][j] j += 1 This works fine, but I was looking for a different solution, just for kicks, and came across something interesting. I can do: i, j = range(len(M)), range(len(M)-1, -1, -1) i [0, 1, 2] j [2, 1, 0] Theoretically, I could then just iterate over range(len(M)) and grab M[i[N]j[N]], but that's not legal. What would be the right way of doing this? Thanks in advance, Carlos ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] newbie: write ArcGIS lists to file?
zack holden [EMAIL PROTECTED] wrote I need to begin producing .csv files of this list that I can access using other programs. Would someone be willing to post a few lines of code showing me how to write the list the code above creates to an external file? Check the documentation for the csv module, I beliebe it supports both reading and writing CSV files. Alan G. ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] List elements as indices to another list
Carlos Laviola [EMAIL PROTECTED] wrote i [0, 1, 2] j [2, 1, 0] Theoretically, I could then just iterate over range(len(M)) and grab M[i[N]j[N]], but that's not legal. What would be the right way of doing this? M [ i[N] ] [ j[N] ] You just missed a couple of brackets... HTH, Alan G ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
