in NumPy, how to insert an array into another array

Question

For example, if I have a NumPy array

import numpy as np

a = np.arange(10)
b = np.zeros(5)

How can I insert b to the beginning of a?

I know I can make a new array of size len(a)+len(b) and do slice assignment, but is there a way to directly insert the array?

Luke · Accepted Answer · 2013-04-03 00:22:56Z

3

How about this:

c = np.hstack([b, a])

answered Apr 3, 2013 at 0:22

Luke

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Comments

Blender · Accepted Answer · 2013-04-03 00:23:11Z

2

You can use numpy.concatenate:

>>> np.concatenate((b, a))
    array([ 0.,  0.,  0.,  0.,  0.,  0.,  1.,  2.,  3.,  4.,  5.,  6.,  7.,
        8.,  9.])

answered Apr 3, 2013 at 0:23

Blender

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