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NumPy: Save a given array to a text file and load it

NumPy: Basic Exercise-37 with Solution

Write a NumPy program to save a given array to a text file and load it.

Sample Solution :

Python Code :

import numpy as np
import os
x = np.arange(12).reshape(4, 3)
print("Original array:")
print(x)
header = 'col1 col2 col3'
np.savetxt('temp.txt', x, fmt="%d", header=header) 
print("After loading, content of the text file:")
result = np.loadtxt('temp.txt')
print(result)

Sample Output:

Original array:
[[ 0  1  2]
 [ 3  4  5]
 [ 6  7  8]
 [ 9 10 11]]
After loading, content of the text file:
[[  0.   1.   2.]
 [  3.   4.   5.]
 [  6.   7.   8.]
 [  9.  10.  11.]]

Pictorial Presentation:

NumPy: Save a given array to a text file and load it.

Python-Numpy Code Editor:

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Previous: Write a NumPy program to save two given arrays into a single file in compressed format (.npz format) and load it.
Next: Write a NumPy program to convert a given array into bytes, and load it as array.

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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