list comprehension - Printable Version

list comprehension - Printable Version

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list comprehension - 3lnyn0 - Jul-11-2022

Hi! I try to modify the function below with list comprehation.
But I don't now how to write that else secvantion

This:

def cakes(recipe, available):
    list_value = [ ]
    for key,value in recipe.items():
        if key in available:
            a = int(available[key]) // int(value)
            list_value.append(a)
        else:
            return 0
    list_value.sort()
    return list_value[0]

In this:

def cakes(recipe, available):
    list_value = [int(available[key]) // int(value) for key,value in recipe.items() if key in available else return 0  ].sort()
    return list_value[0]

RE: list comprehension - deanhystad - Jul-12-2022

def cakes(recipe, available):
    values = [int(available[key]) // int(value) for key, value in recipe.items() if key in available]
    if len(values) > 0:
        values.sort()
        return values[0]
    return 0

RE: list comprehension - DeaD_EyE - Jul-12-2022

Quote:[int(available[key]) // int(value) for key,value in recipe.items() if key in available else return 0 ].sort()

The sort method of a list, does not return the list. Instead, the list is sorted inline and returns None, which is assigned to list_value.

You can wrap around the whole list comprehension with the sorted function. The sorted function returns a new list, where the original list is not modified.

If you want to get the highest number of a sequence, use the max function.
To get the lowest number, use min.

Example:

from __future__ import annotations


def cakes(recipe: dict, available: dict) -> int | None:

    values = [
        int(available[key]) // int(value)
        for key, value in recipe.items()
        if key in available
    ]

    if values:
        return min(values)

Annotations: They are not mandatory, but can give you a hint, which types should be used and which types return. For example, an empty recipe will return None. A valid recipe will return an int.

RE: list comprehension - Gribouillis - Jul-12-2022

You can avoid checking if values is empty by using the 'default' argument in min()

>>> min([], default=0)
0

def cakes(recipe, available):
    return min(
        (int(available[key]) // int(value) for key, value in recipe.items() if key in available),
        default=0)

RE: list comprehension - DeaD_EyE - Jul-12-2022

@Gribouillis, thanks.

The blacked Version is easier to read:

def cakes(recipe, available):
    return min(
        (
            int(available[key]) // int(value)
            for key, value in recipe.items()
            if key in available
        ),
        default=0,
    )

The parenthesis for the Generator Expression is not mandatory.