如何附加两个 NumPy 数组？

先决条件： Numpy

Python中的两个数组可以以多种方式附加，下面讨论所有可能的数组。

方法一：使用append()方法

此方法用于将值附加到数组的末尾。

Syntax :

numpy.append(array, values, axis = None)

Parameters :

• array: [array_like]Input array.
• values : [array_like]values to be added in the arr. Values should be 
  shaped so that arr[…,obj,…] = values. If the axis is defined values can be of any 
  shape as it will be flattened before use. 
   
• axis : Axis along which we want to insert the values. By default, array is flattened.

Return :

A copy of array with values being appended at the end as per the mentioned object, along a given axis.

例子：

Python3

import numpy
 
 
array1 = numpy.array([1, 2, 3, 4, 5])
array2 = numpy.array([6, 7, 8, 9, 10])
 
# Appending both arrays using Append method
array1 = numpy.append(array1, array2)
print(array1)

输出：

[ 1  2  3  4  5  6  7  8  9 10]

方法二：使用 concatenate() 方法

Concatenate 方法沿现有轴连接一系列数组。

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.

例子：

蟒蛇3

import numpy
 
 
array1 = numpy.array([1, 2, 3, 4, 5])
array2 = numpy.array([6, 7, 8, 9, 10])
 
# Appending both Arrays using concatenate() method.
array1 = numpy.concatenate([array1, array2])
print(array1)

输出：

[ 1  2  3  4  5  6  7  8  9 10]

方法 3：使用 stack() 方法

Stack 方法 沿新轴连接一系列数组。

Syntax : numpy.stack(arrays, axis)

Parameters :
 

• arrays : [array_like] Sequence of arrays of the same shape.
• axis : [int] Axis in the resultant array along which the input arrays are stacked.

Return : [stacked ndarray] The stacked array of the input arrays which has one more dimension than the input arrays.

例子：

蟒蛇3

import numpy
 
 
array1 = numpy.array([1, 2, 3, 4, 5])
array2 = numpy.array([6, 7, 8, 9, 10])
 
# Join a sequence of arrays along a new axis.
array1 = numpy.stack([array1, array2])
print(array1)

输出：

[[ 1  2  3  4  5] 
 

 [ 6  7  8  9 10]]

方法 4：使用 hstack() 方法

hstack 方法 水平（按列）按顺序堆叠数组。

Syntax : numpy.hstack(tup)

Parameters :
 

• tup : [sequence of ndarrays] Tuple containing arrays to be stacked. The arrays must have the same shape along all but the second axis.

Return : [stacked ndarray] The stacked array of the input arrays.

例子：

蟒蛇3

import numpy
 
 
array1 = numpy.array([1, 2, 3, 4, 5])
array2 = numpy.array([6, 7, 8, 9, 10])
 
# Stack arrays in sequence horizontally (column wise).
array1 = numpy.hstack([array1, array2])
print(array1)

输出：

[ 1  2  3  4  5  6  7  8  9 10]

方法 5：使用 vstack() 方法

vstack 方法 垂直（按行）按顺序堆叠数组。

Syntax : numpy.vstack(tup)

Parameters :
 

• tup : [sequence of ndarrays] Tuple containing arrays to be stacked. The arrays must have the same shape along all but the first axis.

Return : [stacked ndarray] The stacked array of the input arrays.

例子：

蟒蛇3

import numpy
 
 
array1 = numpy.array([1, 2, 3, 4, 5])
array2 = numpy.array([6, 7, 8, 9, 10])
 
# Stack arrays in sequence vertically (row wise).
array1 = numpy.vstack([array1, array2])
print(array1)

输出：

[[ 1  2  3  4  5] 
 

 [ 6  7  8  9 10]]

方法 6 ：使用 column_stack() 方法

column_stack()方法将数组作为列堆叠成二维数组。

Syntax: column_stack( array)

蟒蛇3

import numpy
 
 
array1 = numpy.array([1, 2, 3, 4, 5])
array2 = numpy.array([6, 7, 8, 9, 10])
 
# Stack 1-D arrays as columns into a 2-D array.
array1 = numpy.column_stack([array1, array2])
print(array1)

输出：

[[ 1  6]
 [ 2  7]
 [ 3  8]
 [ 4  9]
 [ 5 10]]