Python numpy.roll()用法及代码示例

numpy.roll(array，shift，axis = None)：沿着指定的轴滚动数组元素。本质上发生的是输入数组的元素被移位。如果将元素首先滚动到last-position，则将其回滚到first-position。

参数：

array : [array_like][array_like]Input array, whose elements we want to roll
shift : [int or int_tuple]No. of times we need to shift array elements.
        If a tuple, then axis must be a tuple of the same size, and each of the given 
        axes is shifted
        by the corresponding number. 
        If an int while axis is a tuple of ints, then the same value is used for all given axes.
axis  :  [array_like]Plane, along which we wish to roll array or shift it's elements.

返回：

Output rolled array, with the same shape as a.

# Python Program illustrating 
# numpy.roll() method 
   
import numpy as geek 
   
array = geek.arange(12).reshape(3, 4) 
print("Original array : \n", array) 
   
# Rolling array; Shifting one place 
print("\nRolling with 1 shift : \n", geek.roll(array, 1)) 
  
# Rolling array; Shifting five places 
print("\nRolling with 5 shift : \n", geek.roll(array, 5)) 
  
# Rolling array; Shifting five places with 0th axis 
print("\nRolling with 5 shift with 0 axis : \n", geek.roll(array, 2, axis = 0))

输出：

Original array : 
 [[ 0  1  2  3]
 [ 4  5  6  7]
 [ 8  9 10 11]]

Rolling with 1 shift : 
 [[11  0  1  2]
 [ 3  4  5  6]
 [ 7  8  9 10]]

Rolling with 5 shift : 
 [[ 7  8  9 10]
 [11  0  1  2]
 [ 3  4  5  6]]

Rolling with 5 shift with 0 axis : 
 [[ 4  5  6  7]
 [ 8  9 10 11]
 [ 0  1  2  3]]

参考文献：
https://docs.scipy.org/doc/numpy-dev/reference/generated/numpy.roll.html