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Python

Posted by Nathan McGinley
Nathan McGinley
4,627 Points

Can someone explain why this works?

So I know this code works but I don't understand how it does:

def loopy(items):
    for item in items:
        if item[0] == "a":
            continue
        print(item)

Shouldn't it be:

def loopy(items):
    for item in items:
        if items[0] == "a":
            continue
        print(item)

items is the list(array) and item is the variable holding the value for each index and as such isn't a list so how does this work, I'm so confused.

1 Answer

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

items[0] is the first element of the list passed in as an argument. It will have the same value for the entire function execution.

item[0] is the first character of the loop variable item. item points to each successive element in the argument items as the loop iterates over items.

A string offset and slicing notation uses the same index notation as a list.

Mixing these concepts, you can use items[0][0] to get the first character of the first word in the wordlist items.

Nathan McGinley
Nathan McGinley
4,627 Points

Ah thanks, makes sense now! I got all muddled up.

mykolash
mykolash
12,955 Points
mykolash
mykolash
12,955 Points

Hi Nathan McGinley.

Yep, Chris Freeman explained it. The only thing concerning: "Mixing these concepts, you can use items[0][0] to get the first character of the first word in the wordlist items."

Yes, if you need " the first character of the first word in the wordlist items" you can use [0][0]. But. If you don't know specific item #? Then you can use iterator (like "i" - like [i][j]) - like all "crappy" C++/Java/... languages do. And this trick is needed in Python too, but rather rarely. More often we can use other cool Pythonic tricks to solve iteration needs - like enumerate, for example.

But I think you've already studied it. During last 7 months. Before I've posted this comment. ^_^

Pls, excuse me if I'm just confusing you.