What is the numpy.roll() in Python?

NumPy roll() function helps us to rotate the orientation of a NumPy array by a specified value. In simple words, it helps us to shift the elements of an array from the left to the right direction.

Let's consider an array arr [1, 2, 3, 4]. To shift all of the elements by a factor of 1, the array would be changed to [4, 1, 2, 3].

In this article, we will learn about the syntax and parameters of the NumPy roll() function, along with some examples for better understanding.

Syntax for NumPy roll()

The syntax for NumPy roll() function is:

Parameters for NumPy roll()

The parameters for NumPy roll() function are:

• arr: This mandatory parameter represents the input array.
• shift: The value of this necessary parameter indicates how many times the array elements need to be shifted from left to right.
• axis: This optional parameter indicates the plane along which we want to roll/shift our input array.

Return Type for NumPy roll()

The return type for NumPy roll() is a shifted NumPy array with the same dimensions and specifications as the input array.

Examples for NumPy roll()

• Rolling a flat array

  In this example, we will roll/shift a one-dimensional array using the NumPy roll() function in Python.

  Output

• Rolling a two-dimensional array

  In this example, we will roll/shift a two-dimensional array using the NumPy roll() function in Python. We will also keep changing the factor of roll/shift.

  Output

• Rolling a NumPy array by row

  In this example, we will rotate an array row-wise only, using the axis parameter. We do this by specifying the axis to be 0.

  Output

• Rolling a NumPy array by column

  In this example, we will rotate an array column-wise only, using the axis parameter. We do this by specifying the axis to be 1.

  Output