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Dhruv Ghulati
1,582 PointsHow to take comma separated inputs for list, challenge part 2?
First part of challenge solved via:
print(','.join(shopping_list))
For the second part, would I include error handling via:
if not ',' in input('>'):, print('You have an invalid input'), else shopping_list.append(new_item)?
3 Answers
Chris Freeman
Treehouse Moderator 68,441 PointsYour error handling, as written, requires that the input must have a comma. Does this mean you wish to not allow adding items one at a time?
Instead of checking for a comma on the input, you can simply split() the input into a list. The code below captures input into new_items then adds them to the shopping_list. Note the use of extend() instead of append() since split() returns a list:
new_items = input('>')
shopping_list.extend(new_item.split(','))
If the input is a single item, split simply returns a list consisting of that one item. Caution: split only removes the splitting character. If you split on comma and the user includes spaces then the spaces will be part of the item string. It will take more code to handle both cases of commas and commas+spaces. Perhaps removing all spaces before splitting or parsing the input with a intermediate Python regular expression
Marni Kostman
7,558 Pointschris freeman Here is the code I just came up with. It may have some spacing issues but it only uses the functions we have learned up to this point in Kenneth's videos.
shopping_list = [] #could also use list() function
print("What should we pick up at the store?")
print("Enter 'DONE' to stop adding items.")
while True: #true is never a reason to stop...will go on forever
new_item=input("> ")
if new_item == "DONE":
break #breaks the loop
new_item=new_item.split(", ")
for item in new_item:
shopping_list.append(item)
print("Added! List has {} items.".format(len(shopping_list)))
continue #continues the loop/starts over
print("Here's your list:")
for item in shopping_list: #don't have to call them "items" - can call them anything - all elements of container, when we get to last item in list, loop stops
print(item)
I originally just added the line with split but, when I did that, it was counting the whole entry as 1 item. When I added the extra "for" loop, the "Added!" line worked and accurately counted items.
Chris Freeman
Treehouse Moderator 68,441 PointsLooks Good! Three critiques::
- The
continuestatement is not required at the end of awhileblock. Continue is the default action at the end of the code block - You're correct on using "item" over "items" for the iterating variable name since it refers to a singular 'thing' from the reference sequence
shopping_list -
new_itemmight be better named asnew_itemsoritems_listto indicate it is a sequence. The statement then becomes more readable asfor item in new_items: .... - If user enters a blank item, the empty item will be added to the list. You may wish to add a check for this case and skip adding the blank item
Keep up the good work!
Marni Kostman
7,558 PointsThanks, chris freeman...will definitely update with your suggestions!