Multiply different size nested array with scalar

Question

In my python code, I have an array that has different size inside like this

arr = [
    [1],
    [2,3], 
    [4],
    [5,6,7],
    [8],
    [9,10,11]
]

I want to multiply them by 10 so it will be like this

arr = [
        [10],
        [20,30], 
        [40],
        [50,60,70],
        [80],
        [90,100,110]
    ]

I have tried arr = np.multiply(arr,10) and arr = np.array(arr)*10

it seems that both are not working for different size of nested array because when I tried using same size nested array, they actually works just fine

[[i*10 for i in sublist] for sublist in arr] without numpy — sahasrara62
– sahasrara62, Commented Dec 20, 2022 at 9:30

Jip Helsen · Accepted Answer · 2022-12-20 09:32:05Z

1

It is best to just use a nested loop :

arr = [
    [1],
    [2,3], 
    [4],
    [5,6,7],
    [8],
    [9,10,11]
]

def matrix_multiply_all(matrix,nb):
    return list(map(lambda arr : list(map(lambda el : el*nb,arr)),matrix))
print(matrix_multiply_all(arr,10))

answered Dec 20, 2022 at 9:32

Jip Helsen

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Comments

Talha Tayyab · Accepted Answer · 2022-12-20 09:45:31Z

1

You can do with list comprehension as sahasrara62 mentioned if it is a list:

[[i*10 for i in x] for x in arr]

answered Dec 20, 2022 at 9:45

Talha Tayyab

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