# Python NumPy nonzero() Function

Python NumPy` nonzero()` function is used to return the indices (the index numbers or index positions) of the elements of an array that are non-zero. It returns a tuple of arrays, one for each dimension of arr, containing the indices of the non-zero elements in that dimension. In this article, I will explain `numpy.nonzero()` function and use this syntax, parameters, and return indices of elements that are non-zero with examples.

## 1. Quick Examples of Python NumPy nonzero() Function

If you are in a hurry, below are some quick examples of how to use Python NumPy nonzero() function. For more creators of ndarray refer NumPy Tutorial.

``````
# Below are the quick examples

# Example 1: Indices of non zero elements
arr = np.array([8, 23, 45, 0, 60, 0, 85, 0, 101])
arr2 = np.nonzero(arr)

# Example 2: All nonzero elements
arr3 = arr[arr2]

# Example 3: Index of all elements which are greater than 50
arr2 = np.nonzero(arr > 50)

# Example 4: Use nonzero() function to 2-d array
arr = np.array([[4, 0, 0], [0, 6, 0], [-7, 15, 0]])
arr2 = np.nonzero(arr)

# Example 5: Get the corresponding non-zero number
arr3 = arr[np.nonzero(arr)]

# Example 6: Use numpy.transpose() to indices of non-zero number
arr = np.array([[4, 0, 0], [0, 6, 0], [-7, 15, 0]])
arr3 = np.transpose(np.nonzero(arr))
``````

## 2. Syntax of Python numpy.nonzero()

Following is the syntax to create` numpy.nonzero()` function.

``````
# Python numpy.nonzero() Syntax
numpy.nonzero(arr)
``````

## 2.1 Parameters of NumPy nonzeros()

• `arr : `Input array.

## 2.2 Return Value of nonzeros()

It returns Indices of elements that are non-zero.

## 3. Get Indices of nonzero Elements Use nonzero()

We can use NumPy `nonzero() `function is used to get index of all elements which are non-zero.

``````
import numpy as np

# Create one-dimensional array with nonzero
arr = np.array([8, 23, 45, 0, 60, 0, 85, 0, 101])

# Indices of non zero elements
arr2 = np.nonzero(arr)
print (arr2)

# Output:
# (array([0, 1, 2, 4, 6, 8], dtype=int64),)

# All nonzero elements
arr3 = arr[arr2]
print(arr3)

# Output:
# [  8  23  45  60  85 101]
``````
``````
# Index of all elements which are greater than 50
arr2 = np.nonzero(arr > 50)
print (arr2)

# Output:
# (array([4, 6, 8], dtype=int64),)
``````

## 4. Use nonzero() Function to 2-D Array

``````
import numpy as np

# Create two-dimensional array with nonzero
arr = np.array([[4, 0, 0], [0, 6, 0], [-7, 15, 0]])

# Use nonzero() function to 2-d array
arr2 = np.nonzero(arr)
print (arr2)

# Output:
(array([0, 1, 2, 2], dtype=int64), array([0, 1, 0, 1], dtype=int64))

# Get the corresponding non-zero number
arr3 = arr[np.nonzero(arr)]
print(arr3)

# Output:
# [ 4  6 -7 15]
``````

## 5. Use numpy.transpose() Function to Indices of non-zero Number

``````
# Use numpy.transpose() function to indices of non-zero number
arr = np.array([[4, 0, 0], [0, 6, 0], [-7, 15, 0]])
arr3 = np.transpose(np.nonzero(arr))
print(arr3)

# Output:
# [[0 0]
#  [1 1]
#  [2 0]
# [2 1]]
``````

## 6. Conclusion

In this article, I have explained how to use Python NumPy `nonzero()` function using indices of elements that are non-zero with examples.

Happy Learning!!

### Vijetha

With 5 of experience in technical writing, I have had the privilege to work with a diverse range of technologies like Python, Pandas, NumPy and R. During this time, I have consistently demonstrated my ability to grasp intricate technical details and transform them into comprehensible materials. 