numpy.random.randn() in Python

Last Updated : 17 May, 2024

The numpy.random.randn() function creates an array of specified shape and fills it with random values as per standard normal distribution.
If positive arguments are provided, randn generates an array of shape (d0, d1, …, dn), filled with random floats sampled from a univariate “normal” (Gaussian) distribution of mean 0 and variance 1 (if any of the d_i are floats, they are first converted to integers by truncation). A single float randomly sampled from the distribution is returned if no argument is provided.
Syntax :

numpy.random.randn(d0, d1, ..., dn)

Parameters :

d0, d1, ..., dn : [int, optional]Dimension of the returned array we require,        If no argument is given a single Python float is returned.

Return :

Array of defined shape, filled with random floating-point samples from   the standard normal distribution.

Code 1 : randomly constructing 1D array

Python3

   # Python Program illustrating 
# numpy.random.randn() method 
   
import numpy as geek 
   
# 1D Array 
array = geek.random.randn(5) 
print("1D Array filled with random values : \n", array); 
 
  

Output :

1D Array filled with random values :    [-0.51733692  0.48813676 -0.88147002  1.12901958  0.68026197]

Code 2 : randomly constructing 2D array

Python3

   # Python Program illustrating 
# numpy.random.randn() method 
   
import numpy as geek 
   
# 2D Array    
array = geek.random.randn(3, 4) 
print("2D Array filled with random values : \n", array); 
 
  

Output :

2D Array filled with random values :    [[ 1.33262386 -0.88922967 -0.07056098  0.27340112]   [ 1.00664965 -0.68443807  0.43801295 -0.35874714]   [-0.19289416 -0.42746963 -1.80435223  0.02751727]]

Code 3 : randomly constructing 3D array

Python3

   # Python Program illustrating 
# numpy.random.randn() method 
   
import numpy as geek 
   
# 3D Array      
array = geek.random.randn(2, 2 ,2) 
print("3D Array filled with random values : \n", array); 
 
  

Output :

3D Array filled with random values :    [[[-0.00416587 -0.66211158]    [-0.97254293 -0.68981333]]     [[-0.18304476 -0.8371425 ]    [ 2.18985366 -0.9740637 ]]]

Code 4 : Manipulations with randomly created array

Python3

   # Python Program illustrating 
# numpy.random.randn() method 
   
import numpy as geek 
   
# 3D Array      
array = geek.random.randn(2, 2 ,2) 
print("3D Array filled with random values : \n", array); 
       
# Multiplying values with 3 
print("\nArray * 3 : \n", array *3) 
  
# Or we cab directly do so by  
array = geek.random.randn(2, 2 ,2) * 3 + 2
print("\nArray * 3 + 2 : \n", array); 
 
  

Output :

3D Array filled with random values :    [[[ 1.9609643  -1.89882763]    [ 0.52252173  0.08159455]]     [[-0.6060213  -0.86759247]    [ 0.53870235 -0.77388125]]]    Array * 3 :    [[[ 5.88289289 -5.69648288]    [ 1.56756519  0.24478366]]     [[-1.81806391 -2.6027774 ]    [ 1.61610704 -2.32164376]]]    Array * 3 + 2 :    [[[-2.73766306  6.80761741]    [-1.57909191 -1.64195796]]     [[ 0.51019498  1.30017345]    [ 3.8107863  -4.07438963]]]