flatten list of numpy arrays while keeping inner arrays-CodePudding

l = [np.array([[1,2],[3,4]]), np.array([5,6]), np.array([[7,8],[9,10],[11,12]])]

I'm trying to flatten this list of arrays but keeping the inner arrays:

[[1, 2], [3, 4], [5, 6], [7, 8], [9, 10], [11, 12]]

I tried itertools.chain, np.concatenate, np.flatten but none of these options give the output above

CodePudding user response：

Your arrays have different numbers of dimensions, you need to ensure they all are 2D:

out = np.concatenate([x[None,:] if x.ndim == 1 else x for x in l])

output:

array([[ 1,  2],
       [ 3,  4],
       [ 5,  6],
       [ 7,  8],
       [ 9, 10],
       [11, 12]])

or with itertools.chain with a list output:

from itertools import chain
list(chain.from_iterable([x.tolist()] if x.ndim == 1 else x.tolist()
                         for x in l))

output: [[1, 2], [3, 4], [5, 6], [7, 8], [9, 10], [11, 12]]

CodePudding user response：

You haven't provided your desired output. But, as I understood, you are looking for this:

x = [[1, 2], [3, 4], [5, 6], [7, 8], [9, 10], [11, 12]]
print([n for m in x for n in m])

with output:

[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12]

Please let me know if this is not your desired output.