np.concatenate 数组拼接

concatenate((a1, a2, …), axis=0)官方文档详解

concatenate((a1, a2, ...), axis=0)

Join a sequence of arrays along an existing axis.

Parameters
----------
a1, a2, ... : sequence of array_like
    The arrays must have the same shape, except in the dimension
    corresponding to `axis` (the first, by default).
axis : int, optional
    The axis along which the arrays will be joined.  Default is 0.

Returns
-------
res : ndarray
    The concatenated array.

See Also
--------
ma.concatenate : Concatenate function that preserves input masks.
array_split : Split an array into multiple sub-arrays of equal or
              near-equal size.
split : Split array into a list of multiple sub-arrays of equal size.
hsplit : Split array into multiple sub-arrays horizontally (column wise)
vsplit : Split array into multiple sub-arrays vertically (row wise)
dsplit : Split array into multiple sub-arrays along the 3rd axis (depth).
stack : Stack a sequence of arrays along a new axis.
hstack : Stack arrays in sequence horizontally (column wise)
vstack : Stack arrays in sequence vertically (row wise)
dstack : Stack arrays in sequence depth wise (along third dimension)

2、Parameters参数

需要指定拼接的方向，默认是 axis = 0，纵向拼接，也就按列方向拼接；axis=1是横向拼接，按行方向拼接。

传入的数组必须在拼接方向axis轴上形状一致

import numpy as np

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

np.concatenate((a,b), axis=0)
array([[1, 2, 3],
       [4, 5, 6],
       [7, 8, 9]])
np.concatenate((a,c), axis=1)
array([[ 1,  2,  3, 11],
       [ 4,  5,  6, 12]])