在NumPy中拆分数组

数组分割可以是垂直的，水平的，或深度的。我们可以分别使用函数hsplit()、vsplit()和dsplit()进行同样的操作。我们可以通过指明分割后的位置将数组分割成相同形状的数组。

• 水平拆分。’hsplit()’函数沿参数=1的轴分割一个数组。’numpy.hsplit’相当于轴参数=1的’split’，数组总是沿第二个轴分割，而不考虑数组的尺寸。这个函数将一个数组水平地分割成多个子数组(column-wise)。

语法:

numpy.hsplit(ary, indices_or_sections)

示例:

# Horizontal array splitting using np.hsplit()
    import numpy as np
      
      
    # Making of  a 3x3 array
    a = np.arange(9).reshape(3, 3)
      
    # Horizontal splitting of array 
    # 'a' using np.hsplit().
    print("The array {} gets splitted \
    horizontally to form {} ".format(a, np.hsplit(a, 3)))
      
    # Horizontal splitting of array 'a' 
    # using 'split' with axis parameter = 1.
    print("The array {} gets splitted \
    horizontally to form {} ".format(a, np.split(a, 3, 1)))

输出:

The array [[0 1 2]
     [3 4 5]
     [6 7 8]] gets splitted horizontally to form [array([[0],
           [3],
           [6]]), array([[1],
           [4],
           [7]]), array([[2],
           [5],
           [8]])] 
    The array [[0 1 2]
     [3 4 5]
     [6 7 8]] gets splitted horizontally to form [array([[0],
           [3],
           [6]]), array([[1],
           [4],
           [7]]), array([[2],
           [5],
           [8]])]

• 垂直拆分。vsplit() “函数沿参数=0的轴分割一个数组。’numpy.vsplit’相当于轴参数=0的’split’。这个函数将一个数组垂直地分割成多个子数组（一行一列）。

numpy.vsplit(ary, indices_or_sections)

示例:

    import numpy as np  
    # Making of  a 3x3 array
    a = np.arange(9).reshape(3, 3)
      
    # Vertical splitting of array 'a'
    # using np.vsplit().
    print("The array {} gets splitted \
    vertically to form {} ".format(a, np.vsplit(a, 3)))
      
    # Vertical splitting of array 'a' 
    # using 'split' with axis parameter = 0.
    print("The array {} gets splitted \
    vertically to form {} ".format(a, np.split(a, 3, 0)))

输出:

数组[[0 1 2]]
[3 4 5]
[6 7 8]]被垂直分割成[数组([[0, 1, 2]]), 数组([[3, 4, 5]]), 数组([[6, 7, 8]])
数组[[0 1 2]]
[3 4 5]
[6 7 8]]被垂直分割成[数组([[0, 1, 2]]), 数组([[3, 4, 5]]), 数组([[6, 7, 8]])

• 深度分割。它沿第三轴（深度）将阵列分成多个子阵列。

numpy.dsplit(ary, indices_or_sections)

示例:

      
    import numpy as np  
    # Making of  a 3x3x3 array.
    b = np.arange(27).reshape(3, 3, 3)
      
    # Depth-wise splitting of array
    # 'b' using np.dsplit().
    print("The array {} gets splitted \
    depth-wise to form {}".format(b, np.dsplit(b, 3)))

输出:

The array [[[ 0 1 2]   
[ 3 4 5]   
[ 6 7 8]] 

[[ 9 10 11]   
[12 13 14]   
[15 16 17]] 

[[18 19 20]   
[21 22 23]   
[24 25 26]]] gets splitted depth-wise to form [array([[[ 0],   
[ 3],   
[ 6]], 

[[ 9],   
[12],   
[15]], 

[[18],   
[21],   
[24]]]), array([[[ 1],   
[ 4],   
[ 7]], 

[[10],   
[13],   
[16]], 

[[19],   
[22],   
[25]]]), array([[[ 2],   
[ 5],   
[ 8]], 

[[11],   
[14],   
[17]], 

[[20],   
[23],   
[26]]])]