NumPy: Uniform, non-uniform random sample from a given 1-D array with and without replacement

Last update on May 28 2022 13:28:05 (UTC/GMT +8 hours)

NumPy: Basic Exercise-49 with Solution

Write a NumPy program to generate a uniform, non-uniform random sample from a given 1-D array with and without replacement.

Sample Solution :

Python Code :

import numpy as np 
print("Generate a uniform random sample with replacement:") 
print(np.random.choice(7, 5))
print("\nGenerate a uniform random sample without replacement:") 
print(np.random.choice(7, 5, replace=False))
print("\nGenerate a non-uniform random sample with replacement:") 
print(np.random.choice(7, 5, p=[0.1, 0.2, 0, 0.2, 0.4, 0, 0.1]))
print("\nGenerate a uniform random sample without replacement:") 
print(np.random.choice(7, 5, replace=False, p=[0.1, 0.2, 0, 0.2, 0.4, 0, 0.1]))

Sample Output:

Generate a uniform random sample with replacement:
[5 4 4 1 5]

Generate a uniform random sample without replacement:
[1 4 0 3 2]

Generate a non-uniform random sample with replacement:
[4 4 3 0 6]

Generate a uniform random sample without replacement:
[1 4 6 0 3]

Python-Numpy Code Editor:

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Previous: Write a NumPy program to create a two-dimensional array with shape (8,5) of random numbers. Select random numbers from a normal distribution (200,7).
Next: Write a NumPy program to create a 4x4 array with random values, now create a new array from the said array swapping first and last rows.

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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