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Numpy Useful Functions - Create Array Python

Last Updated on Wednesday 5th Oct 2022

Python Create Array

NumPy provides a variety list of functions for creating arrays.

np array

Creating Arrays from Python Sequences

You can create an array from a Python list or tuple by using NumPy’s array function.(2,3 - shaped array)

numpy sequence

			
					import numpy as np

print(np.array([[1, 4, 6], [3, 5, 7]]))

			
	
			
					# [
#  [1 4 6]
#  [3 5 7]
# ]

			
	

Creating 1 dim array with zeros

NumPy provides the functions zeros and ones, which will fill an array of user-specified shape with 0s and 1s.

			
					import numpy as np

print(np.zeros(5))
print(np.ones(5))

			
	

Output

			
					[0. 0. 0. 0. 0.]
[1. 1. 1. 1. 1.]

			
	

Creating new array with 4 rows and 3 columns

[0]*3 will produce [0, 0, 0].

			
					import numpy as np

print(np.array([[0*4]*3]))

print(np.array([[0*4]*3]*2))

			
	
			
					# [
#   [0 0 0]
# ]

# [
#   [0 0 0]
#   [0 0 0]
# ]

			
	

Generate Array Python

			
					import numpy as np

print(np.zeros((4, 3)))

			
	

Output

			
					[
 [0. 0. 0.]
 [0. 0. 0.]
 [0. 0. 0.]
 [0. 0. 0.]
]

			
	

Create a square N × N identity matrix

			
					import numpy as np

print(np.eye(4))

			
	

Output

			
					[
 [1. 0. 0. 0.]
 [0. 1. 0. 0.]
 [0. 0. 1. 0.]
 [0. 0. 0. 1.]
]

			
	

numpy make array

Several functions can be accessed from np.random, which derived arrays randomly.

Creates uniform random numbers

			
					import numpy as np

print(np.random.random((2, 2)))

			
	

Output

			
					[
 [ 0.05802877  0.36875017]
 [ 0.52098717  0.02762662]
]

			
	

Creates random integer (from - to)

			
					import numpy as np

print(np.random.randint(5, 15, (4, 4)))

			
	

Output

			
					[
 [10 14 10  6]
 [ 7  6  6  7]
 [ 7 11  7 12]
 [10  8  7 10]
]

			
	

Joining the Arrays Numpy

numpy create array

			
					import numpy as np

x = np.array([1, 2, 3])
y = np.array([-1, -2, -3])

print(np.vstack([x, y]))
print(np.hstack([x, y]))

			
	
			
					# [
#   [ 1  2  3]
#   [-1 -2 -3]
# ]
# [ 1  2  3 -1 -2 -3]

			
	

References