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Numpy – Set All Values to One in Array

The Numpy library in Python comes with a number of built-in functions to manipulate the data in arrays. In this tutorial, we will look at a function that helps us set all the values in a Numpy array to one.

How to set all values to one in Numpy?

set all values to one in numpy array

You can use the numpy.ndarray.fill() function to set all the values in a Numpy array to one. Pass 1 as the argument (this is the value used to fill all the values in the array).

The following is the syntax –

# set all values in numpy array ar to 1
ar.fill(1)

It modifies the array in-place, filling each value with one (the passed value).

Let’s now look at a step-by-step example of using the above function.

Step 1 – Create a Numpy array

First, we will create a Numpy array that we will use throughout this tutorial.

import numpy as np

# create a numpy array
ar = np.array([-2, -1, 0, 1, 2, 3, -4])
# display the array
print(ar)

Output:

[-2 -1  0  1  2  3 -4]

Here, we used the numpy.array() function to create a Numpy array containing some numbers.

Step 2 – Set each value to 1 using numpy.ndarray.fill()

Apply the numpy.ndarray.fill() function on the array and pass 1 as the parameter to set each value to one in the array.

Let’s apply this function to the array created above.

# set all values to one
ar.fill(1)
# display the array
print(ar)

Output:

[1 1 1 1 1 1 1]

You can see that each value in the array ar is now 1.

The numpy.ndarray.fill() function works similarly on higher-dimensional arrays. For example, let’s apply this function to a 2D array of some numbers.

# create 2D numpy array
ar = np.array([[-1, 2, -3],
               [0, 51, 7],
               [1, 125, 8]])
# set all values to one
ar.fill(1)
# display the array
print(ar)

Output:

[[1 1 1]
 [1 1 1]
 [1 1 1]]

You can see that each value in the above 2D array is now one.

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Author

  • Piyush

    Piyush is a data scientist passionate about using data to understand things better and make informed decisions. In the past, he's worked as a Data Scientist for ZS and holds an engineering degree from IIT Roorkee. His hobbies include watching cricket, reading, and working on side projects.