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Python

Posted by meatballfriday
meatballfriday
2,811 Points

Why do my items come out in reversed order when inserted at a particular index? (Shopping List 3)

I followed the video and this is my code:

shopping_list = []

def show_help():

    print("\nSeperate each item with a comma.")
    print("Type DONE to quit, SHOW to see the current list, and HELP to get this message.")

def show_list():

    count = 1
    for item in shopping_list:
        print("{}: {}".format(count, item))
        count += 1

print("Give me a list of things you want to shop for.")
show_help()

while True:

    new_stuff = input("> ")

    if new_stuff == "DONE":
        print("\nHere is your list:")
        show_list()
        break
    elif new_stuff == "HELP":
        show_help()
        continue
    elif new_stuff == "SHOW":
        show_list()
        continue
    else:
        new_list = new_stuff.split(",")
        index = input("Add this at a certain spot? Press enter for the end of the list, "
                      "or give me a number. Currently {} items in the list. ".format(len(shopping_list)))
        if index:
            spot = int(index) - 1
            for item in new_list:
                shopping_list.insert(spot, item.strip())
            spot += 1
        else:
            for item in new_list:
                shopping_list.append(item.strip())

Below is the result I got when I tried to insert "milk, cream" into the list at index 1 (actually 0). Instead of getting 1. milk and 2. cream, I got 1. cream and 2. milk. How is that possible??

and HELP to get this message.                    
> apple, bananas, yogurt                         
Add this at a certain spot? Press enter for the e
nd of the list, or give me a number. Currently 0 
items in the list.                               
> milk, cream                                    
Add this at a certain spot? Press enter for the e
nd of the list, or give me a number. Currently 3 
items in the list. 1                             
> SHOW                                           
1: cream                                         
2: milk                                          
3: apple                                         
4: bananas                                       
5: yogurt                                        
> DONE                                           

Here is your list:                               
1: cream                                         
2: milk                                          
3: apple                                         
4: bananas                                       
5: yogurt

[MOD: added ``` block markdown formatting -cf]

2 Answers

Chris Freeman
MOD
Chris Freeman
Treehouse Moderator 68,423 Points
Chris Freeman
Chris Freeman
Treehouse Moderator 68,423 Points

The issue is spot is incremented outside the for loop, so all items are added at the same spot shifting over earlier adds. 

         "or give me a number. Currently {} items in the list. ".format(len(shopping_list)))
        if index:
            spot = int(index) - 1
            for item in new_list:
                shopping_list.insert(spot, item.strip())
                spot += 1  # <-- indented inside of for loop
meatballfriday
meatballfriday
2,811 Points
meatballfriday
meatballfriday
2,811 Points

AH I see! Thank you Chris!