w3resource

How to save and load multiple NumPy arrays to and from a single binary file?

NumPy: I/O Operations Exercise-8 with Solution

Write a NumPy program that saves multiple NumPy arrays to a single binary file using np.savez and then loads them back using np.load.

Sample Solution:

Python Code:

import numpy as np

# Create multiple NumPy arrays
array1 = np.array([[10, 20, 30], [40, 50, 60]])
array2 = np.array([[70, 80, 90], [100, 110, 120]])
array3 = np.array([130, 140, 150, 160, 170, 180])

# Define the path to the binary file
binary_file_path = 'multiple_arrays.npz'

# Save multiple NumPy arrays to a single binary file using np.savez
np.savez(binary_file_path, array1=array1, array2=array2, array3=array3)

# Load the NumPy arrays from the binary file using np.load
loaded_data = np.load(binary_file_path)

# Extract the arrays
loaded_array1 = loaded_data['array1']
loaded_array2 = loaded_data['array2']
loaded_array3 = loaded_data['array3']

# Print the original and loaded NumPy arrays
print("Original NumPy Arrays:")
print("Array 1:")
print(array1)
print("Array 2:")
print(array2)
print("Array 3:")
print(array3)

print("\nLoaded NumPy Arrays from Binary File:")
print("Loaded Array 1:")
print(loaded_array1)
print("Loaded Array 2:")
print(loaded_array2)
print("Loaded Array 3:")
print(loaded_array3)

Output:

Original NumPy Arrays:
Array 1:
[[10 20 30]
 [40 50 60]]
Array 2:
[[ 70  80  90]
 [100 110 120]]
Array 3:
[130 140 150 160 170 180]

Loaded NumPy Arrays from Binary File:
Loaded Array 1:
[[10 20 30]
 [40 50 60]]
Loaded Array 2:
[[ 70  80  90]
 [100 110 120]]
Loaded Array 3:
[130 140 150 160 170 180]

Explanation:

  • Import NumPy Library: Import the NumPy library to handle arrays.
  • Create Multiple NumPy Arrays: Define multiple NumPy arrays with some example data.
  • Define Binary File Path: Specify the path where the binary file will be saved.
  • Save Multiple Arrays to Binary File: Use np.savez() to save the multiple NumPy arrays to a single binary file, giving each array a name.
  • Load Arrays from Binary File: Use np.load() to read the contents of the binary file back into a NumPy object.
  • Extract Loaded Arrays: Extract the individual arrays from the loaded data using their respective names.
  • Finally print the original NumPy arrays and the loaded arrays to verify that the data was saved and read correctly.

Python-Numpy Code Editor: