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NumPy: Swap rows and columns of a given array in reverse order

NumPy: Basic Exercise-58 with Solution

Write a NumPy program to swap rows and columns of a given array in reverse order.

Sample Solution:

Python Code:

import numpy as np
nums = np.array([[[1, 2, 3, 4],
               [0, 1, 3, 4],
               [90, 91, 93, 94],
               [5, 0, 3, 2]]])
print("Original array:")
print(nums)
print("\nSwap rows and columns of the said array in reverse order:")
new_nums = print(nums[::-1, ::-1])
print(new_nums)

Sample Output:

Original array:
[[[ 1  2  3  4]
  [ 0  1  3  4]
  [90 91 93 94]
  [ 5  0  3  2]]]

Swap rows and columns of the said array in reverse order:
[[[ 5  0  3  2]
  [90 91 93 94]
  [ 0  1  3  4]
  [ 1  2  3  4]]]
None

Python-Numpy Code Editor:

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Previous: Write a NumPy program to create a 4x4 array, now create a new array from the said array swapping first and last, second and third columns.
Next: Write a NumPy program to multiply two given arrays of same size element-by-element.

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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