Find and index item inside a list of lists

Question

This is for my python algorithms class:
So I have list database which should have lists 1, 2 and 3 (item) inside of it. I have to find a way to find items inside lists 1, 2 and 3 but also print the index of the list which that item belongs inside list database

This is how it’s setup:

database = []
name = input('type the name')
desc = input('type the description')
item = [name, desc]
database.append(item)

I’ve tried making a variable that scans for the specific item inside the lists of lists which kinda worked, but I can only make it show that this item exists in one of the item lists and can’t actually index the list of which that item belongs to inside database.

Asked By: Ryan Duarte

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Source

Answer 1

This is one way to do it:

>>> database = [["pizza", "description-of-pizza"], ["burger", "description-of-burger"], ["soup", "description-of-soup"]]
...
>>> for index, (name, description) in enumerate(database):
...   if name == "burger":
...     print(index, name, description)
... 
1 burger description-of-burger

Answered By: Selcuk

Answer 2

You want to use the enumerate function.

You give it an iterable (items through which you can iterate using a for loop), e. g. lists, strings, etc. and it gives you index, at which some item is stored within that iterable, and that very item.

For example, the code below:

for index, symbol in enumerate("Hi!"):
    print(f"Index: {index}. Symbol: '{symbol}'.")

Will print the following:

Index: 0. Symbol: 'H'.

Index: 1. Symbol: 'i'.

Index: 2. Symbol: '!'.

enumerate with other iterables will work the same.

The code that does your job:

database = []

for i in range(3):
    name = input('Type the name: ')
    desc = input('Type the description: ')
    item = [name, desc]
    database.append(item)
    # database.append([name, desc]) - shorter

for index, item in enumerate(database):
    # Do something with index and item
    print(f'Index: {index}. Item: {item}')

Answered By: Firegreat

Find and index item inside a list of lists

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