Numpy - add row to array

user_233816 0
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How does one add rows to a numpy array?

I have an array A:

A = array([[0, 1, 2], [0, 2, 0]])

I wish to add rows to this array from another array X if the first element of each row in X meets a specific condition.

Numpy arrays do not have a method 'append' like that of lists, or so it seems.

If A and X were lists I would merely do:

for i in X:
    if i[0] < 3:
        A.append(i)

Is there a numpythonic way to do the equivalent?

Thanks, S ;-)

rows numpy arrays python
10 Answers
import numpy as np
array_ = np.array([[1,2,3]])
add_row = np.array([[4,5,6]])

array_ = np.concatenate((array_, add_row), axis=0)
user_85315780

I use numpy.insert(arr, i, the_object_to_be_added, axis) in order to insert object_to_be_added at the i'th row(axis=0) or column(axis=1)

import numpy as np

a = np.array([[1, 2, 3], [5, 4, 6]])
# array([[1, 2, 3],
#        [5, 4, 6]])

np.insert(a, 1, [55, 66], axis=1)
# array([[ 1, 55,  2,  3],
#        [ 5, 66,  4,  6]])

np.insert(a, 2, [50, 60, 70], axis=0)
# array([[ 1,  2,  3],
#        [ 5,  4,  6],
#        [50, 60, 70]])

Too old discussion, but I hope it helps someone.

user_130691830
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