# numpy.concatenate() function | Python

• Difficulty Level : Basic
• Last Updated : 22 Apr, 2020

numpy.concatenate() function concatenate a sequence of arrays along an existing axis.

Syntax : numpy.concatenate((arr1, arr2, …), axis=0, out=None)
Parameters :
arr1, arr2, … : [sequence of array_like] The arrays must have the same shape, except in the dimension corresponding to axis.
axis : [int, optional] The axis along which the arrays will be joined. If axis is None, arrays are flattened before use. Default is 0.
out : [ndarray, optional] If provided, the destination to place the result. The shape must be correct, matching that of what concatenate would have returned if no out argument were specified.
Return : [ndarray] The concatenated array.

Code #1 :

 # Python program explaining# numpy.concatenate() function  # importing numpy as geek import numpy as geek  arr1 = geek.array([[2, 4], [6, 8]])arr2 = geek.array([[3, 5], [7, 9]])  gfg = geek.concatenate((arr1, arr2), axis = 0)  print (gfg)

Output :

[[2 4]
[6 8]
[3 5]
[7 9]]

Code #2 :

 # Python program explaining# numpy.concatenate() function  # importing numpy as geek import numpy as geek  arr1 = geek.array([[2, 4], [6, 8]])arr2 = geek.array([[3, 5], [7, 9]])  gfg = geek.concatenate((arr1, arr2), axis = 1)  print (gfg)

Output :

[[2 4 3 5]
[6 8 7 9]]

Code #3 :

 # Python program explaining# numpy.concatenate() function  # importing numpy as geek import numpy as geek  arr1 = geek.array([[2, 4], [6, 8]])arr2 = geek.array([[3, 5], [7, 9]])  gfg = geek.concatenate((arr1, arr2), axis = None)  print (gfg)

Output :

[2 4 6 8 3 5 7 9]

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