CODEWITHSUNDEEP
pythonarraysnumpyinsertconcatenation
kinder chen
kinder chen

Reputation: 1461

how to efficiently insert element for a n dimension array

There is a simple example.

I have a 2d array

a=np.arange(4).reshape(2,2)+1

array([[1, 2],
       [3, 4]])

and I wanna insert 0 (or any other value) in the beginning and end of the array, then it becomes

array([[ 0.,  0.,  0.,  0.],
       [ 0.,  1.,  2.,  0.],
       [ 0.,  3.,  4.,  0.],
       [ 0.,  0.,  0.,  0.]])

I'm trying np.insert or np.concatenate, but I failed for >2 dimension. What is the fastest way to handle this kind of problem?

Upvotes: 0

Views: 40

Answers (1)

Francisco
Francisco

Reputation: 11496

Use numpy.pad:

>>> np.pad(a, 1, 'constant')
array([[0, 0, 0, 0],
       [0, 1, 2, 0],
       [0, 3, 4, 0],
       [0, 0, 0, 0]])

Upvotes: 1

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