NumPy: Build an array of all combinations of three NumPy arrays
Build Array of All Combinations of Three Arrays
Write a NumPy program to build an array of all combinations of three NumPy arrays.
Sample Solution:
Python Code:
# Importing the NumPy library and aliasing it as 'np'
import numpy as np
# Creating three lists: 'x', 'y', and 'z'
x = [1, 2, 3]
y = [4, 5]
z = [6, 7]
# Printing the original arrays
print("Original arrays:")
print("Array-1")
print(x)
print("Array-2")
print(y)
print("Array-3")
print(z)
# Creating a new NumPy array by meshgrid to combine elements from 'x', 'y', and 'z'
new_array = np.array(np.meshgrid(x, y, z)).T.reshape(-1, 3)
# Printing the combined array obtained from meshgrid
print("Combine array:")
print(new_array)
Sample Output:
Original arrays: Array-1 [1, 2, 3] Array-2 [4, 5] Array-3 [6, 7] Combine array: [[1 4 6] [1 5 6] [2 4 6] [2 5 6] [3 4 6] [3 5 6] [1 4 7] [1 5 7] [2 4 7] [2 5 7] [3 4 7] [3 5 7]]
Explanation:
In the above code –
- x = [1, 2, 3]: Define the first list 'x' with elements 1, 2, and 3.
- y = [4, 5]: Define the second list 'y' with elements 4 and 5.
- z = [6, 7]: Define the third list 'z' with elements 6 and 7.
- np.meshgrid(x, y, z): Create a meshgrid from the input lists 'x', 'y', and 'z'. The meshgrid is a multidimensional grid that contains the coordinates of all possible combinations of elements from the input lists.
- np.array(np.meshgrid(x, y, z)).T: Transpose the meshgrid to rearrange the axes.
- .reshape(-1, 3): Reshape the transposed array into a 2D array with 3 columns and an automatically calculated number of rows.
- new_array = ...: Assign the reshaped array to the variable 'new_array'.
- Finally print() function prints the resulting 'new_array' containing all possible combinations of elements from lists 'x', 'y', and 'z'.
Python-Numpy Code Editor: