Re: [Tutor] changing char list to int list isn't working
Hi Jim, When you replace num = int(num); it's not changing a list. Due to It only pick a value from a list. You have to pointing to list so, You have to use list[position] using while loop like below listOfNumChars = list(str(intNum)) i = 0 while i len(listOfNumChars): listOfNumChars[i] = int(listOfNumChars[i]) i += 1 print(listOfNumChars) #-- [4, 5, 5] (if you entered 455) Best, Bhanu Pratap -Original Message- From: Tutor [mailto:tutor-bounces+bhanubais=gmail@python.org] On Behalf Of Jim Mooney Sent: Saturday, May 04, 2013 9:43 AM To: tutor@python.org Subject: [Tutor] changing char list to int list isn't working I'm turning an integer into a string so I can make a list of separate chars, then turn those chars back into individual ints, but the resulting list still looks like string chars when I print it. What am I doing wrong? listOfNumChars = list(str(intNum)) for num in listOfNumChars: num = int(num) print(listOfNumChars) # result of 455 entered is ['4', '5', '5'] -- Jim Mooney “For anything that matters, the timing is never quite right, the resources are always a little short, and the people who affect the outcome are always ambivalent.” ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] changing char list to int list isn't working
On 04/05/13 05:13, Jim Mooney wrote: I'm turning an integer into a string so I can make a list of separate chars, then turn those chars back into individual ints, You don't actually need to convert to chars, you could use divmod to do it directly on the numbers: digits = [] root = 455 while root 0: ... root, n = divmod(root,10) ... digits.insert(0,n) ... digits [4, 5, 5] But I suspect the str() method is slightly faster... -- Alan G Author of the Learn to Program web site http://www.alan-g.me.uk/ ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] changing char list to int list isn't working
On 05/04/2013 12:13 AM, Jim Mooney wrote: for num in listOfNumChars: num = int(num) It seems like people learning Python run into this very often. I think the reason is that in most simple cases, it's easier and more intuitive to think that the name IS the object: x = 1 y = 2 print x + y Even though I know it's not a precise description, when I see this code, I think of it as x is 1, y is 2, print x plus y. And you do get expected result, which reinforces this intuition. Of course, a more precise way to think is: name 'x' is assigned to object with value=1 name 'y' is assigned to object with value=2 sum values that currently have assigned names of 'x' and 'y' Therefore, what you are really doing is: for each object in listOfNumChars: assign name 'num' to object (this is done automatically by the loop) assign name 'num' to int(value that has currently assigned name 'num') -m -- Lark's Tongue Guide to Python: http://lightbird.net/larks/ Oaths are the fossils of piety. George Santayana ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
[Tutor] changing char list to int list isn't working
I'm turning an integer into a string so I can make a list of separate chars, then turn those chars back into individual ints, but the resulting list still looks like string chars when I print it. What am I doing wrong? listOfNumChars = list(str(intNum)) for num in listOfNumChars: num = int(num) print(listOfNumChars) # result of 455 entered is ['4', '5', '5'] -- Jim Mooney “For anything that matters, the timing is never quite right, the resources are always a little short, and the people who affect the outcome are always ambivalent.” ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] changing char list to int list isn't working
On Sat, May 4, 2013 at 12:13 AM, Jim Mooney cybervigila...@gmail.com wrote: I'm turning an integer into a string so I can make a list of separate chars, then turn those chars back into individual ints, but the resulting list still looks like string chars when I print it. What am I doing wrong? listOfNumChars = list(str(intNum)) for num in listOfNumChars: num = int(num) print(listOfNumChars) # result of 455 entered is ['4', '5', '5'] The body of your for loop only rebinds the loop variable. It's not appending to a new list or modifying listOfNumChars. As to the latter list, it's redundant since a string is iterable. The following snippet creates the list [4, 5, 5]: num = 455 numlist = [] for c in str(num): numlist.append(int(c)) or using a list comprehension: numlist = [int(c) for c in str(num)] or using map: numlist = list(map(int, str(num))) iterators http://docs.python.org/3/library/stdtypes.html#typeiter built-in functions http://docs.python.org/3/library/functions.html#iter http://docs.python.org/3/library/functions.html#map for statement http://docs.python.org/3/reference/compound_stmts.html#the-for-statement comprehensions http://docs.python.org/3/reference/expressions.html#displays-for-lists-sets-and-dictionaries ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] changing char list to int list isn't working
On 04/05/13 14:13, Jim Mooney wrote: I'm turning an integer into a string so I can make a list of separate chars, then turn those chars back into individual ints, but the resulting list still looks like string chars when I print it. What am I doing wrong? listOfNumChars = list(str(intNum)) This creates a list of characters. for num in listOfNumChars: num = int(num) This walks over the list, setting the variable num to each character in turn, then inside the loop you set the variable num to the converted char-int. But num isn't linked to the list in any way -- num has no memory that the value it got came from a list. Reassigning num inside the loop doesn't touch the list in any way, so naturally the list doesn't change. print(listOfNumChars) # result of 455 entered is ['4', '5', '5'] To split a number into digits, the shortest way is to use a list comprehension: digits = [int(c) for c in str(num)] We can expand that list comp into a for-loop: digits = [] for c in str(num): digits.append(int(c)) Notice that there is no need to convert the string into a list. You can iterate over the characters of a string just fine. If you prefer to create a list, then modify it in place, we can do this: digits = list(str(num)) for position, char in enumerate(digits): digits[position] = int(char) Here we use enumerate() to iterate over pairs of (position, value) instead of just value: py list(abcd) ['a', 'b', 'c', 'd'] py list(enumerate(abcd)) [(0, 'a'), (1, 'b'), (2, 'c'), (3, 'd')] Here's another way, using map: digits = map(int, str(num)) # Python 2.x only digits = list(map(int, str(num))) # Python 3.x or better Why the difference between Python 2.x and 3.x? In 2.x, map is eager, it runs all the way through the string as soon as you call it, returning a list. In 3.x, map is lazy, and only generates values when and as needed. By wrapping the map generator in a call to list, that forces it to run all the way through the string. -- Steven ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
