🌐 Mailman 3 April 2005 - Tutor - python.org

What does Python gain by having immutable types?
by Tony C Nov. 15, 2005

Nov. 15, 2005

A friend recently asked my this didn't modify his original string variable s1="this is a string" s1.replace("is a", "is a short") "this is a short string" print s1 "this is a string" After showing him to change it to this s1 = s1.replace("is a", "is a short") print s1 "this is a short string" He then asked Why is it that the sort operation modfies the original list variable? l1=[] l1.append(3) l1.append(44) l1.append(1) l1.append(22) l1 [3, 44, 1, 22] l1.sort() l1 [1, 3, 22, 44] I don't know, but I think it has something to do with strings being immutable, whiles lists are mutable. So, other than the non-informative answer " because that's how the language was written" are there any other reasons how Python benefits from immutable types? Does it really matter if s1 is a different object, so long as it contains the expected modified string? The list variable is the same object, and contains the sorted list, so why bother with the complexity of immutable types at all?

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Re: Weird import problem with PythonIDE on Mac (was 'import problem')
by Chris Smith May 3, 2005

May 3, 2005

### def y1(): pass def foo(): from __main__ import y1 pass foo() ### Here is a version of the code, stripped of the timeit code. The above segment exhibits the same symptoms as the previously submitted one. Even though I am running this as "__main__" it behaves as though it is not __main__. i.e. if I run this with pyOxide without the 'run as __main__' option, it generates the same ImportError ('Can't import y1') as it does when run in the PythonIDE. In the pythonIDE it generates the error whether the 'run as __main__' option is on or off. As a test of that option, I verified that the following code only runs when the __main__ option is on and it worked as expected: ### if __name__=='__main__': print 'running as main' ### /c

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missing module?
by Jeff Peery May 3, 2005

May 3, 2005

Hello, I get an error message from py2exe that it can't find a module ntpath.py. I pasted the error message below: Traceback (most recent call last): File "wxApp1.py", line 4, in ? File "wx\__init__.pyc", line 42, in ? File "wx\_core.pyc", line 4, in ? File "wx\_core_.pyc", line 9, in ? File "wx\_core_.pyc", line 3, in __load File "C:\Python24\lib\os.py", line 62, in ? import ntpath as path zipimport.ZipImportError: can't find module 'ntpath' I can find ntpath why can't py2exe? how can I get this thing working? thanks for the help. jeff

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tokenize row numbering
by Chris Smith May 2, 2005

May 2, 2005

I got over my intimidation with tokenize and learned to use it to strip comments from code files. In the process, I learned that the tuples that it returns for the position in the code of various tokens is 1-based in the row rather than 0-based, so the tuple pair (3,1),(3,2) would be the start and stop position of the "=" OP in the following code: ### # line 1 according to tokenize tuple # line 2 a=b #line 3 ### Does anyone have an idea of *why* the rows/physical lines of code beginning their count at 1 instead of 0? In order to process the code I either have to subtract 1 from all the first elements of tuple positions or else insert a blank line at the beginning of the list that I make out of my code when I want to process it. Is this a candidate for a feature change request? /c

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guess the number game help
by Diana Hawksworth April 30, 2005

April 30, 2005

Hello list! I have started teaching Python to a group of High School students. I set them the "Guess the Number" game as a GUI as an assignment. One of the students has passed in some script that is foreign to any tutorial work we have done. Some of it is below. Does anyone recognise it? Can you tell me where it would have been downloaded from? I have searched for scripted guess the number games, but there are thousands of them - except for a Python version. If my student has plagiarised - I need to know. TIA Diana from Tkinter import * from whrandom import * class rand: def __init__(self, low, high): #whrandom number is made here self.ro = whrandom() self.num = self.ro.randint(low, high) def number(self): return self.num def set(self): self.num = self.ro.randint(low, high) #this part evaluates the users guess def evaluate_ans(guess_str, whrandom, low_str, high_str, guess_left, \ guess_eval_str, yg_label): guesses_left = int(guess_left.get()) guesses_left = guesses_left - 1 guess_left.set(str(guesses_left)) guess = int(guess_str.get()) if guess == whrandom.number(): #User has guessed the number. guess_eval_str.set("correct") play_agn.configure(state=NORMAL) else: #User has not guessed the number. if guess < whrandom.number(): #Guess is too low. low_str.set(str(guess)) guess_eval_str.set("too low") elif guess > whrandom.number(): #Guess is too high. high_str.set(str(guess)) guess_eval_str.set("too high") guess_str.set("") if guesses_left == 0: #User has no guesses left. yg_label.configure(text="Correct answer:") guess_eval_str.set(str(whrandom.number())) play_agn.configure(state=NORMAL) return #Reset variables for next game def reset(whrandom,play_agn, low_str, high_str, guess_left, guess_str, \ yg_label, guess_eval_str, low, high): play_agn.configure(state=DISABLED) whrandom.set() low_str.set(str(low - 1)) high_str.set(str(high + 1))

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input() : part two
by Servando Garcia April 30, 2005

April 30, 2005

Hello everyone Thank you for the quick response to my last request. Here is an update, the program I am writing takes three values from the user than produces the source code for another program. THE PROBLEM: I needed to prompt the user for three values. I used input() like so M= input("Matrix=") The IDE for Macpython works great. It works to well, it handled the GUI interfaces automatically. By using Macpython a input window was created for user input. User entered code then the source code was generated in the output window. I needed to redirect the output so the user could run the new program. I was unable to redirect the output so I decided to use a terminal to run the program like this Python Meta.py > comp.py By redirecting the output the user could now run the program but there was problems. My nice input window was gone and only a blank line was present. When I entered the the data the outputted file looked like this Matrix=error=alpha I found a work around for the terminal it appears that the message in the input("message") was being assigned to the next variable making Matrix=error=alpha So I created a variable with the input() blank Matrix= input() error= input() alpha= input() print Matrix print error print alpha When I use the terminal to redirect the output it works fine so the user can now run the other program like this Python meta.py > comp.py python comp.py once again thanks to everyone for the ideas. It was the brain storming of this group that lead me down the path I took to solve this problem

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Re: Issue with "Entry"/GUI/PIL
by Alberto Troiano April 30, 2005

April 30, 2005

Hey It's a matter of fancyness (Sorry, I think I invented an English word, :D) you are asking in the same Entry you want them to answer, so in order to answer your question, I'll have to delete the question. Secondly, how can you analyze if you don't give the chance to the user to type an answer???? You can ask and answer on the same Entry(although is no pretty nice but...), but in order to do that you'll have to give the user the oportunity to type and a way to tell Python "I finish please correct me!!!" so that's why I think you'll have to add a Button like Submit and in the command you can put a function that erase the answer and put the message Regards Alberto >From: Brian Wurtzel <gilly775(a)gmail.com> >Reply-To: Brian Wurtzel <gilly775(a)gmail.com> >To: albertito_g(a)hotmail.com >Subject: Re: Issue with "Entry"/GUI/PIL >Date: Fri, 29 Apr 2005 15:22:56 -0700 > >So, I cannot use the original entry box? I have to add a second one? >How come python cannot figure it out in the first entry box, it seems >so obvious... > >= = = Original message = = = > >Replace the 0.0 for only 0 > >But you have a problem. You are inserting the question and that's what the >if clause analyze so it will be always wrong you have to add another Entry >and a submit button so it will analyze the result of the second Entry >Regards > >Alberto > > >From: Brian Wurtzel <gilly775(a)gmail.com> > >Reply-To: Brian Wurtzel <gilly775(a)gmail.com> > >To: tutor(a)python.org > >Subject: [Tutor] Issue with "Entry"/GUI/PIL > >Date: Fri, 29 Apr 2005 09:48:01 -0500 >[Quoted text hidden]><< AL.gif >> > >_______________________________________________ > >Tutor maillist - Tutor(a)python.org > >http://mail.python.org/mailman/listinfo/tutor > >Gaucho Gaucho

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enumerate offset?
by Chris Smith April 29, 2005

April 29, 2005

Does anybody else ever run into the case of using enumerate on a slice but then wish that the original list indices were being returned instead of the ones starting at zero? I would like to see an offset argument that could be used with enumerate: ### l=range(5) for i,li in enumerate(l[3:]): print i, li def myenumerate(l,offset=0): for i,li in enumerate(l): yield i+offset, li print for i,li in myenumerate(l[3:],3): print i,li ### '''--the output-- 0 3 1 4 3 3 4 4 --end output--''' /c

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Re: input()
by Chris Smith April 29, 2005

April 29, 2005

On Friday, Apr 29, 2005, at 09:48 America/Chicago, tutor-request(a)python.org wrote: > Hello and thanks in advance. > I am trying to prompt the user for some input. I need three values > from the user so,I used input() like so; > Matrix = input("Matrix=") > error=input("error=") > alpha= input("alpha=") > using Macpython it works fine but when I use a terminal all I get is > a blank line. When I try to enter at the command line I get this > Matrix=error=alpha= > Also I need to redirect any output from the program into another file, > which is why I used the terminal in the first place. So, I guess I have > two problems > 1. How do I redirect output using Macpython? > 2. How do I use input() while using a terminal? > It seems to work fine here for me, but I'm not sure what you are trying to do. I'm using Python 2.4 under OS 10.2.8. Perhaps you could paste a copy of the terminal prompts as they appear? Here is what my session looked like when I entered 12 and 4 for two inputs: ### csmith% cat go.py a=input('a=') b=input('b=') print a,b csmith% python go.py a=12 b=4 12 4 ### If I make a file and feed it to the program rather than entering the text by hand I get: ### csmith% cat > dat 12 4 ^C csmith% python go.py < dat a=b=12 4 ### If I try to redirect this to a file I get: ### csmith% python go.py < dat > out csmith% cat out a=b=12 4 ### One thing you might try is to change your prompt from something like "a=" to "a=\n" Which of the above scenarios are you trying to work with and what do you want the result to be? It looks like the input to input() is not echoed so you should do that yourself if you want the values the user entered to be displayed in the file/output. e.g. ### csmith% cat go2.py def echoInput(prompt=""): ret = input(prompt) print ret return ret a=echoInput('a=') b=echoInput('b=') print a,b csmith% python go2.py < dat > out csmith% cat out a=12 b=4 12 4 ### /c

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input()
by Servando Garcia April 29, 2005

April 29, 2005

Hello and thanks in advance. I am trying to prompt the user for some input. I need three values from the user so,I used input() like so; Matrix = input("Matrix=") error=input("error=") alpha= input("alpha=") using Macpython it works fine but when I use a terminal all I get is a blank line. When I try to enter at the command line I get this Matrix=error=alpha= Also I need to redirect any output from the program into another file, which is why I used the terminal in the first place. So, I guess I have two problems 1. How do I redirect output using Macpython? 2. How do I use input() while using a terminal?

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