# Python NumPy Reverse Array

NumPy reverse array is used to return a new array with the contents of the original array in reverse order. There are various ways to create or initialize reverse arrays in NumPy, for example by using `slicing`, `numpy.flipud()`, `numpy.flip()`, `numpy.fliplr()`, and `reverse()` functions. In this article, I will explain how to use Python reverse array in different ways with examples.

## 1. Quick Examples of Reverse Array

If you are in a hurry, below are some quick examples of NumPy reverse array in Python.

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

# Example 1: Use reverse a numpy array with the basic slicing method
arr = np.array([2, 5, 8, 14, 25])
arr2 = arr[::-1]

# Example 2: Use flipud() function to reverse a numpy array
arr2 = np.flipud(arr)

# Example 3:reverse a numpy array using numpy.flip() function
arr2 = np.flip(arr)

# Example 4: using reverse() function
arr= array.array('i',[2, 5, 8, 14, 25])
arr.reverse()

# Example 5: Use np.fliplr() function
arr= np.array([[2, 5, 8, 14, 19,25],
[3, 6, 9, 13, 18, 29]])
arr2 = np.fliplr(arr)
``````

## 2. Reverse NumPy Array Using Basic Slicing Method

We can use the basic slicing method to reverse a NumPy array. Use this syntax `[::-1]` as the index of the array to reverse it, and will return a new NumPy array object which holds items in a reversed order. Let’s create a NumPy array using `numpy.array()` and reverse it.

``````
import numpy as np

# Create an 1D input array
arr = np.array([2, 5, 8, 14, 25])

# reverse numpy array use slicing method
arr2 = arr[::-1]
print(arr2)

# Output
# [25 14  8  5  2]
``````

## 3. Use flipud() Function to Reverse a Array

The` numpy.flipud()` function is used to reverse the order or flip the array(entries in each column) in up-down direction. This function preserved the shape of the NumPy array.

### 3.1 Syntax of NumPy flipud()

Following is the syntax of the `numpy.flipud()` function.

``````
# Syntax of flipud()
numpy.flipud(arr)
``````

Following are the parameters of the flipud() function.

• `arr :` Input array.

It returns flipped array in up-down direction.

### 3.2 flipud() Example to Reverse Array

Let’s take the same array used in the above example and flip it using flipud() function.

``````
# Use flipud() function to reverse a numpy array
arr2 = np.flipud(arr)
print(arr2)
``````

Yields the same output as above.

## 4. Use flip() Function to Reverse a Array

Python `np.flip()` function is another method to reverse the order of array elements along the given axis. The shape of the array is preserved, but the elements are reordered.

### 4.1 Syntax of NumPy flip()

Following is the syntax of the np.flip() function.

``````
# Syntax of flip()
numpy.flip(arr, axis=None)
``````

### 4.2 Parameters of flip()

Following are the parameters of the flip() function.

• `arr:` Input array.
• `axis:` Axis or axes along which to flip over. The default, axis=None, will flip over all of the axes of the input array. If axis is negative it counts from the last to the first axis.

### 4.3 flip() Example

Let’s reverse an array by using np.flip() function. It returns reversed array with shape preserved.

``````
# Reverse a numpy array using numpy.flip() function
arr2 = np.flip(arr)
print(arr2)
``````

Yields the same output as above.

## 5. Use numpy.fliplr() Function

The `numpy.fliplr()` function is used to reverse the order of elements for a 2-D array. This flip array entry in each row in the left-right direction. columns are preserved but appear in a different order than before.

### 5.1 Syntax of NumPy fliplr()

Following is the syntax of the `fliplr()` function.

``````
# Syntax of fliplr()
numpy.fliplr(arr)
``````

### 5.2 Parameters of fliplr()

• `arr:` Input array, It must be in 2-D dimensions.

### 5.3 fliplr() Example to Reverse Array

By using this fliplr() method let’s reverse the two-dimensional numpy array. This function takes 2-D array as input and returns the array in the same shape but by reversing the order of elements for each dimension.

``````
# Create a 2D input array
arr= np.array([[2, 5, 8, 14, 19,25],
[3, 6, 9, 13, 18, 29]])

# Use np.fliplr() function
arr2 = np.fliplr(arr)
print(arr2)

# Output
# [[25 19 14  8  5  2]
#  [29 18 13  9  6  3]]
``````

## 6. Use reverse() Function to Reverse the Array Element

We can also use `reverse()` function, returns an iterable with elements in reverse order.

``````
import array

# Create an input array
arr= array.array('i',[2, 5, 8, 14, 25])

# using reverse() function
arr.reverse()
print(arr)

# Output
# array('i', [25, 14, 8, 5, 2])
``````

## 7. Conclusion

In this article, I have explained how to use Python NumPy reverse array in different ways with examples. Also learned how to initialize a reverse array by using NumPy `slicing`, `flipud()`, `flip()`, `fliplr()`, and` reverse()` function.

Happy Learning!!

### References  