The Min() And Max() Functions Of Ndarray

Overiew:

  • The min() and max() functions of numpy.ndarray returns the minimum and maximum values of an ndarray object.

 

  • The return value of min() and max() functions is based on the axis specified.

 

  • If no axis is specified the value returned is based on all the elements of the array.

 

 

Example-ndarray.min(), ndarray.max():

  • The example provided calls min() and max() functions on ndarray objects four times each.
  • Once with no axis specified
  • Thrice with axis values specified - the axis values are 0, 1 and 2.

 

  • Since the ndarray object is a 3-dimensional array object it has 3 indexes.

 

  • The dimension of the ndarray object is given by the tuple (3,3,4).

 

  • That is the ndarray object has three 2-dimensional arrays of shape (3,4).

 

# Example Python program for finding the min value along the given axis of an ndarray

 

# Import numpy module

import numpy as np

 

# Import standard library module random

import random

 

# Create a 3-Dimensional ndarray object

array_3d = np.array([[[1,1,1,1],

                     [2,2,2,2],

                     [3,3,3,3]],

                   

                     [[4,4,4,4],

                     [5,5,5,5],

                     [6,6,6,6]],

                   

                     [[7,7,7,7],

                     [8,8,8,8],

                     [9,9,9,9]]]

                    )

                   

# Print the 3-Dimensional Array

print("Input ndarray:")

print(array_3d)

 

print("Shape of the ndarray:")

print(array_3d.shape)

 

print("Number of dimensions/axis of the ndarray:")

print(array_3d.ndim)

 

                   

# Print the minimum value of the whole array - without considering the axis parameter

print("Minimum value in the whole array:%d"%(array_3d.min()))                   

 

# Print the minimum value for axis = 0

print("Minimum value along the axis 0:")

print(array_3d.min(axis=0))

 

# Print the minimum value for axis = 1

print("Minimum value along the axis 1:")

print(array_3d.min(axis=1))

 

# Print the minimum value for axis = 2

print("Minimum value along the axis 2:")

print(array_3d.min(axis=2))

 

# Print the maximum value of the whole array - without considering the axis parameter

print("Maximum value in the whole array:%d"%(array_3d.max()))                    

 

# Print the maximum value for axis = 0

print("Maximum value along the axis 0:")

print(array_3d.max(axis=0))

 

# Print the maximum value for axis = 1

print("Maximum value along the axis 1:")

print(array_3d.max(axis=1))

 

# Print the maximum value for axis = 2

print("Maximum value along the axis 2:")

print(array_3d.max(axis=2))

 

 

Output:

Input ndarray:

[[[1 1 1 1]

  [2 2 2 2]

  [3 3 3 3]]

 

 [[4 4 4 4]

  [5 5 5 5]

  [6 6 6 6]]

 

 [[7 7 7 7]

  [8 8 8 8]

  [9 9 9 9]]]

Shape of the ndarray:

(3, 3, 4)

Number of dimensions/axis of the ndarray:

3

Minimum value in the whole array:1

Minimum value along the axis 0:

[[1 1 1 1]

 [2 2 2 2]

 [3 3 3 3]]

Minimum value along the axis 1:

[[1 1 1 1]

 [4 4 4 4]

 [7 7 7 7]]

Minimum value along the axis 2:

[[1 2 3]

 [4 5 6]

 [7 8 9]]

Maximum value in the whole array:9

Maximum value along the axis 0:

[[7 7 7 7]

 [8 8 8 8]

 [9 9 9 9]]

Maximum value along the axis 1:

[[3 3 3 3]

 [6 6 6 6]

 [9 9 9 9]]

Maximum value along the axis 2:

[[1 2 3]

 [4 5 6]

 [7 8 9]]


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