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How to get the number of dimensions of a matrix using NumPy in Python?

  • Last Updated : 03 Mar, 2021

In this article, we will discuss how to get the number of dimensions of a matrix using NumPy. It can be found using the ndim parameter of the ndarray() method.

Syntax: no_of_dimensions = numpy.ndarray.ndim

Approach:

  • Create an n-dimensional matrix using numpy package.
  • Use ndim attribute available with numpy array as numpy_array_name.ndim to get the number of dimensions.
  • Alternatively, we can use shape attribute to get the size of each dimension and then use len() function for the number of dimensions.
  • Use numpy.array() function to convert a list to numpy array and use one of the above two ways to get the number of dimensions.

Example 1: 

Python3




import numpy as np
  
  
x = np.arange(12).reshape((3, 4))
    
print(x.ndim)

Output:

2

Example 2:

Python3




import numpy as np
  
  
# create numpy arrays
# 1-d numpy array
_1darr = np.arange(4)      
  
# 2-d numpy array
_2darr = np.arange(15).reshape((5, 3))     
  
# 3-d numpy array
_3darr = np.arange(18).reshape((3, 2, 3))  
  
# printing the type of value obtained using 
# attribute 'ndim'
print("Type of value obtained: ", type(_1darr.ndim))
  
# printing the dimensions of each numpy array
print("Dimensions in _1darr are: ", _1darr.ndim)
print("Dimensions in _2darr are: ", _2darr.ndim)
print("Dimensions in _3darr are: ", _3darr.ndim)
  
# numpy_arr.shape is the number of elements in
# each dimension numpy_arr.shape returns a tuple
# len() of the returned tuple is also gives number
# of dimensions
print("Dimensions in _3darr are: ", len(_3darr.shape))
  
# Use numpy.array() function to convert a list to
# numpy array
__1darr = np.array([5, 4, 1, 3, 2])
__2darr = np.array([[5, 4],[1,2], [4,5]])
print("Dimensions in __1darr are: ", __1darr.ndim)
print("Dimensions in __2darr are: ", __2darr.ndim)

Output:

Type of value obtained:  <class 'int'>
Dimensions in _1darr are:  1
Dimensions in _2darr are:  2
Dimensions in _3darr are:  3
Dimensions in _3darr are:  3
Dimensions in __1darr are:  1
Dimensions in __2darr are:  2

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