NumPy: Convert 1-D arrays as columns into a 2-D array

Last update on March 24 2025 13:39:35 (UTC/GMT +8 hours)

Convert 1D Arrays to 2D (as Columns)

Write a NumPy program to convert 1-D arrays as columns into a 2-D array.
Sample array: (10,20,30), (40,50,60)

Pictorial Presentation:

Sample Solution:

Python Code:

# Importing the NumPy library with an alias 'np'
import numpy as np

# Creating NumPy arrays 'a' and 'b'
a = np.array((10, 20, 30))
b = np.array((40, 50, 60))

# Stacking arrays 'a' and 'b' as columns using np.column_stack
c = np.column_stack((a, b))

# Printing the resulting array 'c'
print(c) 

Sample Output:

[[10 40]                                                               
 [20 50]                                                               
 [30 60]] 

Explanation:

‘a = np.array((10,20,30))’ creates a 1D array a with shape (3,).

‘b = np.array((40,50,60))’ creates another 1D array b with shape (3,).

c = np.column_stack((a, b)): The np.column_stack() function is used to stack the two arrays ‘a’ and ‘b’ as columns in a new 2D array. The resulting array ‘c’ has the shape (3, 2), where the first column contains the elements of ‘a’ and the second column contains the elements of ‘b’.

For more Practice: Solve these Related Problems:

• Write a NumPy program to convert two 1D arrays into a single 2D array where each array forms a column using np.column_stack.
• Stack two 1D arrays column-wise and verify the output shape matches the expected dimensions.
• Implement a function that reshapes a 1D array into a 2D column vector using np.reshape.
• Use np.newaxis to convert a 1D array into a 2D column array and compare it with the output of np.atleast_2d.

Python-Numpy Code Editor: