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NumPy: Add a vector to each row of a given matrix

NumPy: Basic Exercise-34 with Solution

Write a NumPy program to add a vector to each row of a given matrix.

Sample Solution :

Python Code :

import numpy as np
m = np.array([[1,2,3], [4,5,6], [7,8,9], [10, 11, 12]])
v = np.array([1, 1, 0])
print("Original vector:")
print(v)
print("Original matrix:")
print(m)
result = np.empty_like(m) 
for i in range(4):
  result[i, :] = m[i, :] + v
print("\nAfter adding the vector v to each row of the matrix m:")
print(result)

Sample Output:

Original vector:
[1 1 0]
Original matrix:
[[ 1  2  3]
 [ 4  5  6]
 [ 7  8  9]
 [10 11 12]]

After adding the vector v to each row of the matrix m:
[[ 2  3  3]
 [ 5  6  6]
 [ 8  9  9]
 [11 12 12]]

Pictorial Presentation:

NumPy: Add a vector to each row of a given matrix.

Python-Numpy Code Editor:

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Python: Tips of the Day

Find current directory and file's directory:

To get the full path to the directory a Python file is contained in, write this in that file:

import os 
dir_path = os.path.dirname(os.path.realpath(__file__))

(Note that the incantation above won't work if you've already used os.chdir() to change your current working directory, since the value of the __file__ constant is relative to the current working directory and is not changed by an os.chdir() call.)

To get the current working directory use

import os
cwd = os.getcwd()

Documentation references for the modules, constants and functions used above:

  • The os and os.path modules.
  • The __file__ constant
  • os.path.realpath(path) (returns "the canonical path of the specified filename, eliminating any symbolic links encountered in the path")
  • os.path.dirname(path) (returns "the directory name of pathname path")
  • os.getcwd() (returns "a string representing the current working directory")
  • os.chdir(path) ("change the current working directory to path")

Ref: https://bit.ly/3fy0R6m