[Python] Iterables and Generators (2) - Flattening a multi-dimensional list

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This post is continued from Iterables and Generators(1)-theory

Prior Knowledge of hasattr() and list.extend(obj) is encouraged.

Basically, our code will check if one element is iterable object or not. If one element has an attribute that is called ‘__iter__’, it means the element is the list inside the given list which we want to extend it.
Of course you can directly check its type by type(x) == list. However, I just wanted to show you guys that it has the ‘__iter__’ attribute.

Flattening a 2-Dimensional List

twoDList = [4, 3, 7, [1, 2, 3], 35, 9]

flattened = []

for x in twoDList:
    if hasattr(x, '__iter__'):
        flattened.extend(x)
    else:
        flattened.append(x)

Flattening a n-Dimensional List

Can recursively call the function.

nDList = [4, 3, 7, [1, 2, [10, 20, 30, [5]], 3], 35, 9]

def flatten(data):
    flattend = []
    for x in data:
        if hasattr(x, '__iter__'):
            flattend.extend(flatten(x))
        else:
            flattend.append(x)
    return flattend

Continue Reading this topic at
Iterables and Generators (3) - itertools