The Numpy library in Python comes with a number of built-in functions to perform common mathematical operations on arrays. In this tutorial, we will look at one such function that helps us get the elementwise sign (positive, negative, or zero) of a Numpy array with the help of some examples.

## How to get the sign of values in Numpy array?

You can use the `numpy.sign()`

function to get the sign of each element in a Numpy array. Pass the array as an argument.

The following is the syntax –

numpy.sign(ar)

It returns an array containing the sign of each element. A positive element has sign 1, a negative element has sign -1, and zero has sign 0. (We’re basically applying the mathematical signum function on each element).

Let’s now look at a step-by-step example of using the `numpy.sign()`

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 numpy array ar = np.array([1, -3, 4, 0, 5, -2, -7]) # display the array print(ar)

Output:

[ 1 -3 4 0 5 -2 -7]

Here, we used the `numpy.array()`

function to create a Numpy array containing some numbers. You can see that this array contains both positive and negative numbers (along with a 0).

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### Step 2 – Get the sign of every element using `numpy.sign()`

To get the sign of each element in a Numpy array, pass the array as an argument to the `numpy.sign()`

function.

Let’s get the sign of elements in the array created above.

# get the sign of each element np.sign(ar)

Output:

array([ 1, -1, 1, 0, 1, -1, -1])

We get a Numpy array with the sign of each element in the array `ar`

.

The `numpy.sign()`

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, -3, 4], [0, 5, -2], [-6, 8, -7]]) # get the sign of each element np.sign(ar)

Output:

array([[ 1, -1, 1], [ 0, 1, -1], [-1, 1, -1]])

You can see that we get the sign of each element in the 2D array.

For more on the `numpy.sign()`

function, refer to its documentation.

You might also be interested in –

- Get the Median of Numpy Array – (With Examples)
- Numpy – Get Standard Deviation of Array Values
- Numpy – Get Min Value in Array

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