How to create an empty and a full NumPy array? (original) (raw)

Last Updated : 28 Jan, 2025

Creating arrays is a basic operation in NumPy.

• **Empty array: This array isn’t initialized with any specific values. It’s like a blank page, ready to be filled with data later. However, it will contain random leftover values in memory until you update it.
• **Full array: This is an array where all the elements are set to the same specific value right from the start. It’s like a sheet filled with one number everywhere.

NumPy provides simple functions numpy.empty() for empty arrays numpy.full() empty arrays and full arrays.

Python `

import numpy as np

Create an empty array of shape (3, 4)

empty_array = np.empty((3, 4)) print("Empty Array:\n", empty_array)

Create a full array of shape (3, 3) filled with the value 5

full_array = np.full((3, 3), 5) print("Full Array:\n", full_array)

`

Output

Empty Array: [[4.63714601e-310 0.00000000e+000 0.00000000e+000 0.00000000e+000] [0.00000000e+000 0.00000000e+000 0.00000000e+000 0.00000000e+000] [0.00000000e+000 0.00000000e+000 0.00000000e+000 0....

**How to Create an Empty NumPy Array?

Creating an empty array is useful when you need a placeholder for future data that will be populated later. It allocates space without initializing it, which can be efficient in terms of performance.

• Use the np.empty() function.
• Specify the shape of the array as a tuple.
• Optionally, define the data type using the dtype parameter. Python `

import numpy as np

empty_array_2d = np.empty((3, 4)) print(empty_array_2d)

`

Output

[[1.13473609e-313 0.00000000e+000 2.10077583e-312 6.79038654e-313] [2.22809558e-312 2.14321575e-312 2.35541533e-312 6.79038654e-313] [2.22809558e-312 2.14321575e-312 2.46151512e-312 2.41907520e-312]...

**How to Create a Full NumPy Array?

A full array is ideal when you need an array initialized with a specific value, such as zeros or ones, which is common in many mathematical computations. **Steps:

• Use the np.full() function.
• Pass the desired shape and fill value.
• Optionally, specify the data type. Python `

import numpy as np

full_array_2d = np.full((3, 4), 5) print(full_array_2d)

`

Output

[[5 5 5 5] [5 5 5 5] [5 5 5 5]]