[Tutor] List issues
Hi Im having trouble completing this function with lists. Im supposed to create a function that will let me know if there are repeating elements so I wrote this and am not sure where the error lies. It is supposed to count the number of times a number appears and if its greater than 1 then it will say True. #Problem 3 list = [1,2,2,2,3,4] def duplicate(list): for i in range(len[list]): if list.count(i) 1: return True print duplicate(list) Gabe Wheeler (512)964-5421 ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] List issues
Wheeler, Gabriel wrote: Im having trouble completing this function with lists. Im supposed to create a function that will let me know if there are repeating elements so I wrote this and am not sure where the error lies. It helps you (and us) a lot if you clearly state the error you are seeing. If your script bails out with an error post the complete traceback. If all appears to be working, but you get a wrong or unexpected result say what you get and what you expected. Running your code I get $ cat check_dupes.py list = [1,2,2,2,3,4] def duplicate(list): for i in range(len[list]): if list.count(i) 1: return True print duplicate(list) $ python check_dupes.py Traceback (most recent call last): File check_dupes.py, line 8, in module print duplicate(list) File check_dupes.py, line 4, in duplicate for i in range(len[list]): TypeError: 'builtin_function_or_method' object has no attribute '__getitem__' Looking at the line shown in the traceback for i in range(len[list]): what could be the function you are not calling but asking for that strange __getitem__ attribute? Hint: def hello(name): ... print Hello,, name ... hello(Gabriel) Hello, Gabriel hello[Gabriel] Traceback (most recent call last): File stdin, line 1, in module TypeError: 'function' object has no attribute '__getitem__' That sure looks similar to your error message. Once you have fixed that I recommend that you add a print statement def duplicate(list): for i in range(len[list]): # must be fixed print looking for, i if list.count(i) 1: return True You'll see that you are looking for items that are not in the list? Can you figure out why? If not, call the function with another list duplicate([a, b, b, b, c, d]) It is supposed to count the number of times a number appears and if its greater than 1 then it will say True. #Problem 3 list = [1,2,2,2,3,4] def duplicate(list): for i in range(len[list]): if list.count(i) 1: return True print duplicate(list) ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] List issues
Wheeler, Gabriel wheel...@seattleu.edu Wrote in message: (not much I could read there. This is a text mailing list, so please tell your mail program to send in text mode, not html. Only parts of your code were visible here, and your question not at all. Fortunately, Peter quoted all or most of your message. His comments are all good. Mine are in addition, not instead. Your code: list = [1,2,2,2,3,4] def duplicate(list): for i in range(len[list]): if list.count(i) 1: return True print duplicate(list) Peter's hints should fix your main bugs. Then: When an if-test doesn't seem to be doing what you expect, add a print statement right before it of the exact expression it's testing. Or even make a new variable of the expression so you can be sure you're looking at the same thing. When a standard method seems to be misbehaving, look up its definition. What should the argument to count be? list is a typename in the standard library, so it really shouldn't be used to name your own objects. I'd use something like mylist. Whenever you see a loop like for i in range(len[list]): be suspicious of it. Usually you want the items, not the indices. for item in mylist: This function doesn't return any value if the if test always fails. Is that what you wanted? -- DaveA ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] List issues
- Original Message - From: Dave Angel da...@davea.name To: tutor@python.org Cc: Sent: Thursday, April 17, 2014 12:03 PM Subject: Re: [Tutor] List issues quot;Wheeler, Gabriel wheel...@seattleu.edu Wrote in message: (not much I could read there. This is a text mailing list, so please tell your mail program to send in text mode, not html. Only parts of your code were visible here, and your question not at all. Fortunately, Peter quoted all or most of your message. His comments are all good. Mine are in addition, not instead. Your code: list = [1,2,2,2,3,4] def duplicate(list): for i in range(len[list]): if list.count(i) 1: return True print duplicate(list) Peter's hints should fix your main bugs. Then: When an if-test doesn't seem to be doing what you expect, add a print statement right before it of the exact expression it's testing. and/or use the pdb debugger (still on my own todo list, but I know it is useful!): http://pymotw.com/2/pdb/ ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] List issues
Hi Gabriel,
Try lists of non-numbers as your input, and the error should be a
little clearer to see. You should see the conceptual error you're
making if not everything in your program is numeric.
Try:
words = ['hello', 'world', 'hello']
print(words.count(0))
print(words.count('hello'))
First write down what you'd expect to see from this. Then execute
this snippet. Does your expectations match what you see?
---
A main bug in your program is that parts of your program are using
numbers for list indices, and other parts of your program are using
numbers as elements, but there's a little confusion in using one
notion for the other.
---
Good luck!
___
Tutor maillist - Tutor@python.org
To unsubscribe or change subscription options:
https://mail.python.org/mailman/listinfo/tutor
