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numpy.roll() in Python
  • Last Updated : 08 Dec, 2020

The numpy.roll() function rolls array elements along the specified axis. Basically what happens is that elements of the input array are being shifted. If an element is being rolled first to last-position, it is rolled back to first-position.

Syntax :

numpy.roll(array, shift, axis = None)

Parameters :

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.

Return :

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))


Output :



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]]

References :
https://docs.scipy.org/doc/numpy-dev/reference/generated/numpy.roll.html

Note :
These codes won’t run on online-ID. Please run them on your systems to explore the working.
This article is contributed by Mohit Gupta_OMG πŸ˜€. If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.

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