Python: One-liner to perform an operation upon elements in a 2d array (list of lists)?

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I have a list of lists, each containing a different number of strings. I'd like to (efficiently) convert these all to ints, but am feeling kind of dense, since I can't get it to work out for the life of me. I've been trying: newVals = [int(x) for x in [row for rows in values]]

Where 'values' is the list of lists. It keeps saying that x is a list and can therefore not be the argument if int(). Obviously I'm doing something stupid here, what is it? Is there an accepted idiom for this sort of thing?

operation 2d matrix arrays python
6 Answers

In order to map list with any number of dimensions you could use numpy.apply_over_axes

import numpy as np
np.apply_over_axes(lambda x,_:x*2, np.array([[1,2,3],[5,2,1]]),[0])
--------------------
array([[ 2,  4,  6],
       [10,  4,  2]])

Unfortunately that doesn't work if you also need to change variable type. Didn't find any library solution for this, so here is the code to do that:

def map_multi_dimensional_list(l, transform):
    if type(l) == list and len(l) > 0:
        if type(l[0]) != list:
            return [transform(v) for v in l]
        else:
            return [map_multi_dimensional_list(v, transform) for v in l]
    else:
        return []
            
map_multi_dimensional_list([[[1,2,3],[5,2,1]],[[10,20,30],[50,20,10]]], lambda x:x*2)
------------------
[[[2, 4, 6], [10, 4, 2]], [[20, 40, 60], [100, 40, 20]]]
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