🌐 Mailman 3 April 2006 - Tutor - python.org

How Big Is Too Big?
by John Connors May 3, 2006

May 3, 2006

G'day, Just wondering how many lines of code is the maximum to post in the list to have it critiqued. I realise people are using their own time to help others in here for no real personal gain and I would hate to impose on their goodwill. Would about 100 lines of code be considered too much? John _________________________________________________________________ New year, new job there's more than 100,00 jobs at SEEK http://a.ninemsn.com.au/b.aspx?URL=http%3A%2F%2Fninemsn%2Eseek%2Ecom%2Eau&_…

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Splitting strings into blocks
by Daniel Watkins May 1, 2006

May 1, 2006

Hi list, I'm currently working on a program to parse LaTeX style maths expressions and provide an answer. For example, I have the expression "2^\frac{1}{2}". I'm trying to work out a way to split this into it's most basic blocks of LaTeX (i.e. 2^ and \frac{1}{2}) while maintaining a record of the depth of the expression (i.e. (2^,0),(\frac{1}{2},1)). I will then process this list from the highest order downwards, feeding the deeper results progressively into shallower elements until all have been calculated. LaTeX allows me to legally express the previously stated expression as "{2^{\\frac{1}{2}}}". This makes it much easier to figure out where the units of LaTeX are located. The depth of any item can now be expressed as the number of unpaired opening or closing braces between the element and the start or end of the expression. I'm essentially looking for a way to split the string up along the braces, while recording the number of braces between the split and either end of the expression. Any help would be much appreciated. Cheers, Dan

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Strange Question
by GNULinuxGeek April 30, 2006

April 30, 2006

All, First, I think this is a wonderful list. I always see great advice and great attitudes about helping. My post is not about evaluating code but instead trying to get a reasonable judgment as to whether or not python is the best choice for what I am trying to do. I have not learned Python yet. In point of fact, I have not, as yet learned any programming language much to my dismay. I post the process I need below. So, here goes the work flow I need to support on my job. 1. Person goes to a web page. 2. The page allows them to retrieve a file from their local hard drive. 3. They make one or two selections with check boxes or drop lists that define things about image resolution and preferences. 4. They enter their E-Mail address to allow the resultant file to be sent back to them. 5. They submit the graphics file (TIFF image) along with the selections and the file is uploaded. 6. The code on the server drops the file in a directory created from the submitted file name. 7. The Python code (cgi script?) calls another application (server resident) that performs processing on the graphics file. 8. The original file, a processed "proof" file and a raw bitmap file are stored back in the created directory. 9. The resultant proof file is sent back to them in an E-Mail message for their approval. 10. The person would then go back to another page and "OK" the file and then the processed image would be sent to yet another E-Mail address. Does anyone see a problem with Python doing this? Also, from my knowledge position in programming and in Python (zero), should I attempt this? Thanks, Best Regards, and keep up the great work, Ralph

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Re: [Tutor] how to *really* copy a list
by kevin parks April 29, 2006

April 29, 2006

Ed, I should have realized that the nesting would create the problem, but i didn't have that in mind... i always thought that the difference between extend and append was that extend did not yield a nested list. I really need to revisit this issue and get it right in my mind. It is a 'gotcha' that i remember reading about often but, now that it has bit me a few times hehe .... so much to know... -kevin-- On Apr 29, 2006, at 6:00 AM, tutor-request(a)python.org wrote: >> >> Hi Kevin, >> >> Your problem is this line: >> seq.extend(foo) >> >> This is the line that mutates your original list. >> >> There are a few ways you could procede here. One way is to make a >> copy of the argument, like this: >> >> def mirror(seq): >> start = list(seq) >> end = seq[:-1] >> end.reverse() >> start.extend(end) >> return start >> >> Notice that we've not calling any methods on seq, so seq won't be >> changed. The first line, "start = list(seq)", instructs python to >> build a new list out of the elements of seq. You could also write >> "start = seq[:]" here --- I'm not sure which is the preferred way. > > A little 'gotcha' with this is that if you have nested lists, these > methods don't copy the nested lists, only the outer list (which makes > sense, but can be surprising the first time you encounter it). If for > some reason you want to copy nested lists, look into deepcopy(), > otherwise you'll be fine.

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Re: [Tutor] how to *really* copy a list
by kevin parks April 29, 2006

April 29, 2006

John, Thanks. Your message was very helpful. I will tattoo it to my forehead. hehe... i notice that the "learning python" book also explains so of this and i shall study that as well.... cheers, kevin On Apr 27, 2006, at 10:14 PM, tutor-request(a)python.org wrote: > > On 28/04/06, kevin parks <kp8(a)mac.com> wrote: >> In most case you are fine operating on the list in place and altering >> the >> existing list. In some cases you want your code to stop molesting >> your poor >> mutables and really honestly sincerly copy the dang thing. In this >> case i am >> making a function that does odd smmetry mirroring. But i want my >> orginal list >> to remain intact.... >> >> def mirror(seq): >> """odd symmetry mirroring [1, 2, 3, 4] --> [1, 2, 3, 4, 3, >> 2, 1]""" >> foo=seq[:-1] # copy list, >> excluding last element for odd symetry >> foo.reverse() # flip it >> seq.extend(foo) >> return seq > > Hi Kevin, > > Your problem is this line: > seq.extend(foo)

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Re: [Tutor] cycle w/ shuffle
by kevin parks April 29, 2006

April 29, 2006

Thanks Kent. That is what i did the first time around but it didn't work ... but that was do to something else that was not working in the script.... hehe.... of course, this just shuffles the saved copy of the list which is egg-zactly what i needed "duh" ... sorry... gosh... <red face=on> -kevin-- On Apr 27, 2006, at 6:00 AM, tutor-request(a)python.org wrote: > kevin parks wrote: >> it seems to me that i need something like itertools cycle, except that >> i need to keep track of when i have exhausted my list and then call >> random.shuffle() on my sequence. >> >> def cycle(iterable): >> saved = [] >> for element in iterable: >> yield element >> saved.append(element) >> while saved: > random.shuffle(saved) ############### >> for element in saved: >> yield element > > Kent

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Re: [Tutor] question concerning deepcopy
by Gregor Lingl April 29, 2006

April 29, 2006

Kent Johnson schrieb: > Gregor Lingl wrote: > >>Thanks, Kent for the hint. It works (of course). >>Skimming through this part of the docs I discovered, that there is a >>special method __deepcopy__. So I also tried using this, adding >> >> def __deepcopy__(self,visit): >> return self >> >>to my Vec class, which also seems to work. (I think this not to >>be harmful as Vecs should be, like tuples, immutable). >>And, indeed, it also seems to work. > > > That is not a correct deep copy, it is a shallow copy. Although Vec > objects are immutable they may contain mutable objects. The point of > deep copy is to copy "all the way down" so the objects contained by a > Vec should also be copied. O.k. I understand. It's just that my Vec class invariably has two numbers as elements (otherwise the abs-method wouldn't make sense. That's what I meant with 'Vecs are immutable'). So in my case it works, but would have to be considered bad style? Thanks, again Gregor > Kent > > _______________________________________________ > Tutor maillist - Tutor(a)python.org > http://mail.python.org/mailman/listinfo/tutor > > -- Gregor Lingl Reisnerstrasse 3/19 A-1030 Wien Telefon: +43 1 713 33 98 Mobil: +43 664 140 35 27 Website: python4kids.net

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Silly Dice Game
by John Connors April 29, 2006

April 29, 2006

G'day, The wife and I play a silly dice game and I thought it would be a good challange for me to write it as a program. No specific question, just wondering if my technique is ok and is there anything that could be done better. The 2 hardest things I find as a python beginner who has no real need to learn a programming language other than curiosity and too much spare time, are thinking of something to program and then knowing if what I have written could be done more efficiently. import random def removeDice(): for a in range(3): dieList.remove(checkThree) while True: dieLeft = 6 totalScore = 0 while dieLeft > 0: dieList = [] score = 0 # roll the dice if dieLeft == 6: raw_input("\nPress enter to roll the dice ") print for dieRoll in range(dieLeft): dieList.append(random.randint(1,6)) print "Die roll %d is %d" % (dieRoll +1, dieList[dieRoll]) dieList.sort() if dieLeft == 6: #check if all dice are the same for fatChance in range(1,7): if dieList.count(fatChance) == 6: score += 5000 dieLeft = 0 print "\nYou rolled all %d's, WoW!!!" % (fatChance) #check for a straight if dieList == [1,2,3,4,5,6]: score += 1500 dieLeft = 0 print "\nYou rolled a straight" #check for 3 pairs if dieLeft == 6: if dieList[0] == dieList[1] and dieList[2] == dieList[3] and dieList[4] == dieList[5]: score += 1500 dieLeft = 0 print"\nYou rolled three pairs" #check for 3 of a kind if dieLeft > 2: for checkThree in range(1,7): if dieList.count(checkThree) >= 3: print "\nYou rolled three %d's" % (checkThree) yourChoice = raw_input("\nDo you wish to keep them? y/n ") if yourChoice == 'y': dieLeft -= 3 if checkThree == 1: score += 1000 removeDice() else: score = score + checkThree * 100 removeDice() #check for 1's and 5's if 1 in dieList or 5 in dieList: for testDice in range(dieLeft): if dieList[testDice] == 1: score += 100 dieLeft -= 1 if dieList[testDice] == 5: score += 50 dieLeft -= 1 totalScore = totalScore + score if score != 0: print "\nYour score is %d and you have %d dice left" % (totalScore, dieLeft) if score == 0: print "\nYou busted and score nothing" totalScore = 0 break if dieLeft >= 1: rollAgain = raw_input ("\nRoll the remaining dice? y/n ") if rollAgain != "y": break if dieLeft == 0: dieLeft = 6 print "\nYou used all the dice and must roll again" print "\n\nYour total score for that round was %d" % (totalScore) playAgain = raw_input("\nPlay again? (y/n) ") print if playAgain != "y": break John _________________________________________________________________ realestate.com.au: the biggest address in property http://ninemsn.realestate.com.au

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question concerning deepcopy
by Gregor Lingl April 29, 2006

April 29, 2006

Hi all of you, I've some Vector class, which is a subclass of tuple and which is working satisfactorily since long in different contexts. Now I've constructed objects with attributes of Vec-type, which I wanted to deepcopy. But that doesn't work, because I can't (deep)copy Vec-s: >>> from copy import deepcopy >>> class Vec(tuple): def __new__(cls, x, y): return tuple.__new__(cls, (x,y)) def __abs__(self): return (self[0]**2+self[1]**2)**0.5 ## more methods ... >>> a=Vec(3,4) >>> abs(a) 5.0 >>> b = deepcopy(a) Traceback (most recent call last): File "<pyshell#13>", line 1, in -toplevel- b = deepcopy(a) File "C:\Python24\lib\copy.py", line 204, in deepcopy y = _reconstruct(x, rv, 1, memo) File "C:\Python24\lib\copy.py", line 336, in _reconstruct y = callable(*args) File "C:\Python24\lib\copy_reg.py", line 92, in __newobj__ return cls.__new__(cls, *args) TypeError: __new__() takes exactly 3 arguments (2 given) Explanation? Remedy? Bug? Workaround? Regards, Gregor -- Gregor Lingl Reisnerstrasse 3/19 A-1030 Wien Telefon: +43 1 713 33 98 Mobil: +43 664 140 35 27 Website: python4kids.net

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Python and Oracle
by Linda Kvam April 28, 2006

April 28, 2006

I have Oracle 10g and Python 2.4 on my PC. I just installed cx_Oracle and then entered - import cx_Oracle -in PythonWin and got the following error - >>> import cx_Oracle Traceback (most recent call last): File "<interactive input>", line 1, in ? ImportError: DLL load failed: The specified procedure could not be found. >>> I have XP Professional OS and in my Path, I have Python24 (where my python executables are), Python24/Scripts and the path for oci.dll (Oracle's dll). I installed Oracle's Developer Suite from a CD and I downloaded Oracle 10G - so I'm not sure if I have Oracle Client - I think I have to do something on the Oracle side but I'm not sure what. When I installed cx_Oracle, 2 files were added to my directory Python24 - I have attached the log file for your information - I know the removecx_oracle works because I have run it. Any hints or ideas you have will be appreciated. Thanks, Linda Kvam lindakvam(a)lynxconsulting.us

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