Re: [Tutor] IF statements
WM [EMAIL PROTECTED] wrote to IF. The code below was not written by me. It is a copy/paste job from the tutor. I do not have any idea what is going wrong. x = int(raw_input(Please enter an integer: )) Please enter an integer: 42 if x 0: ... x = 0 ... print 'Negative changed to zero' ... elif x == 0: ... print 'Zero' ... elif x == 1: ... print 'Single' ... else: ... print 'More' ... More 12 SyntaxError: invalid syntax It looks as if you maybe cut more than you intended? Also I'm not sure about the ... prompts. I don't have 2.6 yet so maybe its an enhancement to IDLE but notmally IDLE doesn't print ... prompts. Did you cut n paste them too? If so that would confuse IDLE. 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] IF Statements
the script ending with .py/.pyw
extension (command-line script/GUI script), although python doesn't
complain if it is not in those extension (in Windows, the extension is
associated with the interpreter). Calling a program from command line is
done like this:
python filename.py
That should get me going ... a book and manual by my side should
suffice for
the rest - - - except for one thing:
2. I have been unable to locate the gizmo in the literature to get
ascii codes
in python. In the old days, it was a list of 256 (or so)
characters that
represented all keyboard symbols (A equalled 36; B equalled 37; et
cetera).
To assign a value, you used Let A$ = ASC (36) where A$ was a
variable
and 36 was the ASCII value for 'A'. I believe the reverse of this
process
was PRINT VAL(A$) or something. I want to play with a program
that will
assign a number to a word (using a simple algorhythm that will give
a
specific number to every word). Other stuff is pretty easy to
find with
the book and on-line literature. I will need to get an ascii code
out of
a string (whose content is not known to the programmer, as
raw_input).
Then to assign, I will need the actual list with assigned numbers.
a = ord('A')
b = chr(36)
-- read on the help file: Built-in Functions
You will be giving me probably the only boost I will need! I will be
available later on,
if I want to take part in the ask/answer system here.
--
Message: 3
Date: Mon, 6 Oct 2008 09:31:04 +0100
From: Alan Gauld [EMAIL PROTECTED]
Subject: Re: [Tutor] IF statements
To: tutor@python.org
Message-ID: [EMAIL PROTECTED]
Content-Type: text/plain; format=flowed; charset=iso-8859-1;
reply-type=response
WM [EMAIL PROTECTED] wrote
to IF. The code below was not written by me. It is a copy/paste
job from the tutor. I do not have any idea what is going wrong.
x = int(raw_input(Please enter an integer: ))
Please enter an integer: 42
if x 0:
... x = 0
... print 'Negative changed to zero'
... elif x == 0:
... print 'Zero'
... elif x == 1:
... print 'Single'
... else:
... print 'More'
...
More
12
SyntaxError: invalid syntax
It looks as if you maybe cut more than you intended?
Also I'm not sure about the ... prompts. I don't have 2.6 yet
so maybe its an enhancement to IDLE but notmally IDLE
doesn't print ... prompts. Did you cut n paste them too?
If so that would confuse IDLE.
HTH,
--
Alan Gauld
Author of the Learn to Program web site
http://www.freenetpages.co.uk/hp/alan.gauld
--
Message: 4
Date: Mon, 6 Oct 2008 09:38:14 +0100
From: Alan Gauld [EMAIL PROTECTED]
Subject: Re: [Tutor] first call - newcomer
To: tutor@python.org
Message-ID: [EMAIL PROTECTED]
Content-Type: text/plain; format=flowed; charset=iso-8859-1;
reply-type=original
Anthony Smith [EMAIL PROTECTED] wrote
This is my first post - I will be brief...
Hi, welcome to tutor :-)
1. A brief (but complete) description regarding the use of script
editor (I will be using command prompt in Windows), as:
Brief and Complete don;t normally go together!
If you are using IDLE then Danny yoo's intro is a good place to start.
The IDLE section of the Python web site has a more detailed run
through oof the faciilities.
a. details about loading and saving programs (not in that
order) and little
specs about pathnames or other requirements (I will
probably store all
my little goodies in one folder or space).
As to paths:
PATH should be set to the folder where the Python interpreters live
PYTHONPATH should be set to include the folder where your code lives
2. I have been unable to locate the gizmo in the literature to get
ascii codes
in python.
chr(n) is the function you need
ord(c) is the one in the opposite direction
but...
was PRINT VAL(A$) or something.
Python will generally figure out what you want to print without
explicit conversions, certainly fewer than you will be used to
from the early BASIC versions.
assign a number to a word (using a simple algorhythm that will
give a
specific number to every word). Other stuff is pretty easy to
find with
the book and on-line literature. I will need to get an ascii
code out of
a string (whose content is not known to the programmer, as
raw_input).
Then to assign, I will need the actual list with assigned
numbers.
OK, You lost me here.
Can you give an example of what the data would look like?
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] IF statements
On Sun, Oct 5, 2008 at 10:51 PM, WM [EMAIL PROTECTED] wrote: I used to do Basic and enjoyed it. Someone said Python was a vastly better language than Visual Basic, which I considered playing with. So I sought to give it a go but struck a sticking point very early. I am now going through the Python tutorial. All went well until I came to IF. The code below was not written by me. It is a copy/paste job from the tutor. I do not have any idea what is going wrong. IDLE 2.6 x = int(raw_input(Please enter an integer: )) Please enter an integer: 42 if x 0: ... x = 0 ... print 'Negative changed to zero' ... elif x == 0: ... print 'Zero' ... elif x == 1: ... print 'Single' ... else: ... print 'More' ... More 12 SyntaxError: invalid syntax Did you paste the and ... or were they printed by the interpreter? Examples often show the entire contents of a session in the interpreter, including the and ... prompts. When you enter the example yourself you should not include them. Also Please enter an integer: is output from the program and 42 is user input to the program, you should not paste either of them. Where did the 12 come from? It looks like interpreter output but there is nothing preceding it that would print a 12. Kent ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] IF Statements
Rajeev Nair [EMAIL PROTECTED] wrote
also i believe the first line can also be written as 'x =
input('enter
...') instead of using x=int(raw_input('..') . use raw_input
for
string and just input for integer.
No, use input() only in very special circumstances or when
experimenting for personal use only.
Use int(raw_input()) for all production code. It is much safer.
--
Alan Gauld
Author of the Learn to Program web site
http://www.freenetpages.co.uk/hp/alan.gauld
___
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Re: [Tutor] IF Statements
On Mon, Oct 6, 2008 at 7:24 AM, Rajeev Nair [EMAIL PROTECTED] wrote:
also i believe the first line can also be written as 'x = input('enter
...') instead of using x=int(raw_input('..') . use raw_input for
string and just input for integer.
Yes, although that is not really recommended, this has been discussed
very recently.
Also, please don't include the entire digest in your reply!
Kent
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[Tutor] IF statements-1
TO THIS ORIGINAL POST I GOT SIX REPLIES. WM wrote: I used to do Basic and enjoyed it. Someone said Python was a vastly better language than Visual Basic, which I considered playing with. So I sought to give it a go but struck a sticking point very early. I am now going through the Python tutorial. All went well until I came to IF. The code below was not written by me. It is a copy/paste job from the tutor. I do not have any idea what is going wrong. IDLE 2.6 x = int(raw_input(Please enter an integer: )) Please enter an integer: 42 if x 0: ... x = 0 ... print 'Negative changed to zero' ... elif x == 0: ... print 'Zero' ... elif x == 1: ... print 'Single' ... else: ... print 'More' ... More 12 SyntaxError: invalid syntax IS THIS THE WAY TO ANSWER? OR SHOULD I DO INDIVIDUAL REPLIES? JOHNSON 1 The copy above is exactly from the book, via COPY PASTE, from IDLE26 thru More. I keyed in the 12 to generate the error message. JOHNSON 2 All that was running was IDLE from the desktop and the tutor from the Python.Org site. I will not do the down-load right now as I want the tutor to work with the program with no tinkering. JOHNSON 3 I did not understand Nair's reply, so I didn't follow thru there. What is the entire digest and how do I not include it? LANE I keyed in 12 Enter. The rest is copy/paste. I will key the text into Notepad then run it, as you suggest. GAULD Not so. You can check on the tutor, the code stops at 'More'. It's funny about the dots, they were in the tutor but not in IDLE, although the indents were the same. Then, in the e-mil, there they were. IDLE hides dots? What do I know? NAIR Your post to me starts, also I believe... It looks like the front end got truncated. ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] IF statements-1
On Mon, Oct 6, 2008 at 9:48 PM, WM [EMAIL PROTECTED] wrote: TO THIS ORIGINAL POST I GOT SIX REPLIES. IS THIS THE WAY TO ANSWER? OR SHOULD I DO INDIVIDUAL REPLIES? Either way is OK. It helps to quote a bit of the post to which you are replying, for context. And please don't use all caps, it is interpreted as shouting. And you seem to be a bit off in your attributions... JOHNSON 1 The copy above is exactly from the book, via COPY PASTE, from IDLE26 thru More. I keyed in the 12 to generate the error message. You can't just paste the examples verbatim from the tutorial. The examples are showing you both the text that you type and the output of the interpreter. In particular the and ... are output and should not be typed or pasted in. JOHNSON 3 I did not understand Nair's reply, so I didn't follow thru there. What is the entire digest and how do I not include it? That was a note to Rajeev, who included a lot of extraneous text in his reply. Did you start at the beginning of the tutorial or are you starting with section 4? Kent ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
[Tutor] IF statements
I used to do Basic and enjoyed it. Someone said Python was a vastly better language than Visual Basic, which I considered playing with. So I sought to give it a go but struck a sticking point very early. I am now going through the Python tutorial. All went well until I came to IF. The code below was not written by me. It is a copy/paste job from the tutor. I do not have any idea what is going wrong. IDLE 2.6 x = int(raw_input(Please enter an integer: )) Please enter an integer: 42 if x 0: ... x = 0 ... print 'Negative changed to zero' ... elif x == 0: ... print 'Zero' ... elif x == 1: ... print 'Single' ... else: ... print 'More' ... More 12 SyntaxError: invalid syntax ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] assignment statements in python
Kermit Rose wrote: Message: 1 Date: Sun, 11 Jun 2006 06:58:39 -0400 From: Kent Johnson [EMAIL PROTECTED] Subject: Re: [Tutor] buggy bug in my program Cc: tutor@python.org Assignment in Python is not a copy, it is a name binding. Assignment creates a name for an object. If you assign the same object to two names, they both are bound to the same thing. If the object is mutable, like a list, changes to the object will be seen regardless of which name you use to refer to it. ** I feel a little bit better now that I know that there is a reason for what my program did. However, I still don't have any idea how to copy values from one cell in an array to the adjacent cell in the same array. You need to copy the value stored in the list, which is itself a list. It must be possible, for otherwise, you could not sort an array. Actually sorting doesn't require copying the values in the list, it just requires moving values to different locations of the list. A list element is somewhat like a name - it is a reference to a value, not a container for a value. If you say a=[1,2,3] b=a then a and b refer to the same list. Likewise, if you say x=[ [1,2,3], [4,5,6] ] x[1] = x[0] then x[1] and x[0] refer to the same list. If you want x[1] (or b) to refer to a new list, you have to copy the old list: x[1] = x[0][:] list[:] is the slice of the list that goes from the beginning to the end - a copy. Kent ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] assignment statements in python
On Sun, 2006-06-11 at 22:14 -0400, Kermit Rose wrote: Message: 1 Date: Sun, 11 Jun 2006 06:58:39 -0400 From: Kent Johnson [EMAIL PROTECTED] Subject: Re: [Tutor] buggy bug in my program Cc: tutor@python.org Assignment in Python is not a copy, it is a name binding. Assignment creates a name for an object. If you assign the same object to two names, they both are bound to the same thing. If the object is mutable, like a list, changes to the object will be seen regardless of which name you use to refer to it. ** In that case, is it possible to copy a variable by value, instead of by reference, in Python? ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] assignment statements in python
On Mon, 2006-06-12 at 09:37 -0400, Kermit Rose wrote: From: Python Date: 06/11/06 22:59:38 To: Kermit Rose Cc: Tutor Python Subject: Re: [Tutor] assignment statements in python The basic python objects: numbers, strings, and tuples are immutable and can not be changed (mutated). a = B = 3 B = 4 # binds B to a different object with value 4 # the object with value 3 is unchanged print a 3 ** If I write a = 3 a = 4 a = 5 Are the objects containing 3 and 4 erased when they no longer have a name? Yes ** Container objects such as lists and dictionaries can be changed in place. a = B = [1,2,3] B.append(4) # changes (mutates) B print a [1, 2, 3, 4] ** Good. Now I know a more efficient way to extend an array. I had been creating an entire new array, and equivalencing the old array to it. ** B[2] = B[3] # positions 2 and 3 reference the same object print B [1, 2, 4, 4] print a [1, 2, 4, 4] ** I still don't know how to make it so that If B = [ 1,2,4,5] B.append(value of B[4]) There is no B[4] B[0] is 1 B[1] is 2 B[2] is 4 B[3] is 5 Perhaps you mean to search B looking for the value 4 and then append that value? index_of_4 = B.index(4) # returns index to location of first 4 B.append( B[index_of_4])# appends the 4 to the end of B copy the value of B[2] into B[3] import copy B = [ 1,2,4,5] B[3] = copy.copy(B[2]) B [1, 2, 4, 4] Since 4 is immutable, there is no need to use the copy module, but it is there for when you need to make copies of an object. copy the value 3 into B[2]. B[2] = 3# no need for a copy since 3 is immutable Or, equivalently, If B = [1,2,4,5] Insert the value 3 between B[1] and b[2], B = [ 1,2,4,5] B.insert(2,3) # inserts 3 before B[2] B [1, 2, 3, 4, 5] help(B.insert) insert(...) L.insert(index, object) -- insert object before index (Use q to leave the help screen) so that B becomes [1,2,3,4,5]. Kermit [EMAIL PROTECTED] ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor -- Lloyd Kvam Venix Corp ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
[Tutor] assignment statements in python
Message: 1 Date: Sun, 11 Jun 2006 06:58:39 -0400 From: Kent Johnson [EMAIL PROTECTED] Subject: Re: [Tutor] buggy bug in my program Cc: tutor@python.org Assignment in Python is not a copy, it is a name binding. Assignment creates a name for an object. If you assign the same object to two names, they both are bound to the same thing. If the object is mutable, like a list, changes to the object will be seen regardless of which name you use to refer to it. ** I feel a little bit better now that I know that there is a reason for what my program did. However, I still don't have any idea how to copy values from one cell in an array to the adjacent cell in the same array. I looked at the reference , http://www.effbot.org/zone/python-objects.htm that you gave, but did not gleam any hint from it how to copy values from one place in an array to another place within the same array. It must be possible, for otherwise, you could not sort an array. It is quite remarkable that my not knowing that assignment is not a copy gave me no difficulties before now. Kermit[EMAIL PROTECTED] ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] assignment statements in python
On Sun, 2006-06-11 at 22:14 -0400, Kermit Rose wrote: Message: 1 Date: Sun, 11 Jun 2006 06:58:39 -0400 From: Kent Johnson [EMAIL PROTECTED] Subject: Re: [Tutor] buggy bug in my program Cc: tutor@python.org Assignment in Python is not a copy, it is a name binding. Assignment creates a name for an object. If you assign the same object to two names, they both are bound to the same thing. If the object is mutable, like a list, changes to the object will be seen regardless of which name you use to refer to it. ** I feel a little bit better now that I know that there is a reason for what my program did. However, I still don't have any idea how to copy values from one cell in an array to the adjacent cell in the same array. I looked at the reference , http://www.effbot.org/zone/python-objects.htm that you gave, but did not gleam any hint from it how to copy values from one place in an array to another place within the same array. It must be possible, for otherwise, you could not sort an array. It is quite remarkable that my not knowing that assignment is not a copy gave me no difficulties before now. The basic python objects: numbers, strings, and tuples are immutable and can not be changed (mutated). a = b = 3 b = 4 # binds b to a different object with value 4 # the object with value 3 is unchanged print a 3 Container objects such as lists and dictionaries can be changed in place. a = b = [1,2,3] b.append(4) # changes (mutates) b print a [1, 2, 3, 4] b[2] = b[3] # positions 2 and 3 reference the same object print b [1, 2, 4, 4] print a [1, 2, 4, 4] Kermit[EMAIL PROTECTED] ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor -- Lloyd Kvam Venix Corp ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
[Tutor] import statements in functions?
Is there a convention to be considered for deciding if import statements should be included in a function body? For example, which of these two module layouts would be preferable: # --- MyModule1.py - import foo1, foo2, foo3 import foo_special # several coherent functions here def specialFunction(): doSomethingSpecial() or the embedded import version: # --- MyModule2.py - import foo1, foo2, foo3 import foo_rare # several coherent functions here def specialFunction(): import foo_special doSomethingSpecial() Also, does the choice have any impact on performance/space/etc.? And will the import function get called each time (and possibly ignored) in the second version? The reason I consider the second form is that the module foo_special is only used by the code in specialFunction(), and detracts (IMHO) from understanding the rest of the code in the module. Thanks, Marcus ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] import statements in functions?
Marcus Goldfish wrote: Is there a convention to be considered for deciding if import statements should be included in a function body? For example, which of these two module layouts would be preferable: imports are cached. So once it is imported, it stays imported. The reason I consider the second form is that the module foo_special is only used by the code in specialFunction(), and detracts (IMHO) from understanding the rest of the code in the module. and this is a good reason why you would perform the import inside the function. ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
