Learning Numpy - Simple Tutorial For Beginners - NumPy - Array Creation Routines Part 5¶

A new ndarray object can be constructed by any of the following array creation routines or using a low-level ndarray constructor.

It creates an uninitialized array of specified shape and dtype. It uses the following constructor −

numpy.empty(shape, dtype = float, order = 'C')

Parameter	Description
Shape	Shape of an empty array in int or tuple of int
Dtype	Desired output data type. Optional
Order	'C' for C-style row-major array, 'F' for FORTRAN style column-major array

import numpy as np
x = np.empty([3,2], dtype = int)
print (x)

[[93899461514432             16]
 [            16             16]
 [             0             97]]

Returns a new array of specified size, filled with zeros.

numpy.zeros(shape, dtype = float, order = 'C')

Parameter	Description
Shape	Shape of an empty array in int or tuple of int
Dtype	Desired output data type. Optional
Order	'C' for C-style row-major array, 'F' for FORTRAN style column-major array

# array of five zeros. Default dtype is float 
import numpy as np
x = np.zeros(5)
print (x)

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

import numpy as np
x = np.zeros((5,), dtype = np.int)
print (x)

[0 0 0 0 0]

# custom type 
import numpy as np
x = np.zeros((2,2), dtype = [('x', 'i4'), ('y', 'i4')])
print (x)

[[(0, 0) (0, 0)]
 [(0, 0) (0, 0)]]

Returns a new array of specified size and type, filled with ones.

numpy.ones(shape, dtype = None, order = 'C')

Parameter	Description
Shape	Shape of an empty array in int or tuple of int
Dtype	Desired output data type. Optional
Order	'C' for C-style row-major array, 'F' for FORTRAN style column-major array

# array of five ones. Default dtype is float 
import numpy as np
x = np.ones(5)
print (x)

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

import numpy as np
x = np.ones([2,2], dtype = int)
print (x)

[[1 1]
 [1 1]]

References¶