numpy.median() in Python

numpy.median(arr, axis = None) : Compute the median of the given data (array elements) along the specified axis.

How to calculate median?

• Given data points.
• Arrange them in ascending order
• Median = middle term if total no. of terms are odd.
• Median = Average of the terms in the middle (if total no. of terms are even)

Parameters :
arr : [array_like]input array.
axis : [int or tuples of int]axis along which we want to calculate the median. Otherwise, it will consider arr to be flattened(works on all the axis). axis = 0 means along the column and axis = 1 means working along the row.
out : [ndarray, optional] Different array in which we want to place the result. The array must have the same dimensions as expected output.
dtype : [data-type, optional]Type we desire while computing median.

Results : Median of the array (a scalar value if axis is none) or array with median values along specified axis.

Code #1:

# Python Program illustrating
# numpy.median() method

import numpy as np

# 1D array
arr = [20, 2, 7, 1, 34]

print("arr : ", arr)
print("median of arr : ", np.median(arr))

Output :

arr :  [20, 2, 7, 1, 34]
median of arr :  7.0

Code #2:

# Python Program illustrating
# numpy.median() method
import numpy as np

# 2D array
arr = [[14, 17, 12, 33, 44],
       [15, 6, 27, 8, 19],
       [23, 2, 54, 1, 4, ]]

# median of the flattened array
print("\nmedian of arr, axis = None : ", np.median(arr))

# median along the axis = 0
print("\nmedian of arr, axis = 0 : ", np.median(arr, axis = 0))

# median along the axis = 1
print("\nmedian of arr, axis = 1 : ", np.median(arr, axis = 1))

out_arr = np.arange(3)
print("\nout_arr : ", out_arr)
print("median of arr, axis = 1 : ",
      np.median(arr, axis = 1, out = out_arr))

Output :

median of arr, axis = None :  15.0

median of arr, axis = 0 :  [15.  6. 27.  8. 19.]

median of arr, axis = 1 :  [17. 15.  4.]

out_arr :  [0 1 2]
median of arr, axis = 1 :  [17 15  4]