Table of Contents

## Fill array with random numbers in Python

An array is one of the fundamental data structures in Python. It stores elements in a contiguous memory location and each element can be accessed using its respective index. In Python, the `numpy`

library is used to implement array data structures. Lists are also another data structure that mimics an array in Python.

In this tutorial, we will discuss different methods to fill array with random numbers in Python.

We can create an array of our desired shapes. Sometimes, we may require dummy arrays for some calculations. We can create an array filled with such dummy values since the `numpy`

library also implements a `random`

module to generate random numbers.

## Ways to fill array with random numbers in Python

Let us now discuss how to fill array with random numbers in Python.

### Using the `numpy.random.randint()`

function to fill array with random numbers in Python

As discussed earlier, the `numpy`

library has a `random`

module that can help in generating random numbers for `numpy`

arrays. The `randint()`

function can be used to generate an array of the required size and fill array with random numbers in Python.

We need to remember the three main parameters. The first two parameters are the `low`

and `high`

values. The function will select a random integer between this range. The third parameter is the `shape`

parameter which specifies the shape of the final array.

See the following example.

1 2 3 4 5 |
import numpy as np arr = np.random.randint(0,10,10) print(arr) |

Output:

In the above example, we generate random numbers between 0 to 10 and fill it in a one-dimensional array of length ten.

### Using the `numpy.random.Generator.integers()`

function to fill array with random numbers in Python

The `numpy.random.Generators`

offer a new way to generate and work with random numbers. It uses an additional `BitGenerator`

to spawn such random bits and manage their states. To initiate a new `Generator`

, we use the `numpy.random.default_rng()`

constructor.

After this, we can use the `numpy.random.Generator.integers()`

function to generate random numbers and fill array with random numbers in Python.

We need to specify the `low`

, `high`

, and `shape`

values in this function as we did in the previous method.

For example,

1 2 3 4 5 6 |
import numpy as np g = np.random.default_rng() arr = g.integers(0,5,10) print(arr) |

Output:

## Further reading:

### Using the `random.randint()`

function to fill array with random numbers in Python

As discussed in the first section, lists in Python also mimic an array. We can fill lists with random numbers using the `random`

module in Python. We will use list comprehension along with the `random.randint()`

function to fill array with random numbers in Python.

We will use the `random.randint()`

function to generate a random number between a given range. We will use the list comprehension method that loops over this function the required number of times, creating a new list of the required length.

See the following code.

1 2 3 4 5 |
import random arr = [random.randint(1,5) for _ in range(10)] print(arr) |

Output:

## Conclusion

To conclude, in this tutorial we discussed different methods to fill array with random numbers in Python. Essentially, we were creating arrays with random numbers. For this, we used `numpy`

arrays and lists.

For `numpy`

arrays, we had two methods. The first was the traditional `numpy.random.randint()`

function that generates a `numpy`

array of a given length filled with random numbers between a given range.

In the second method, we used a relatively new `numpy.random.Generators`

module to create the array. It uses `Generators`

that provide an additional state to manage and generate random bits.

In the final method, we discussed how to fill array with random numbers in Python using the list comprehension method and the `random.randint()`

function. Essentially, we create a loop and run the `randint()`

function the required number of times and add the generated number to a list.