median_low() function in Python statistics module (original) (raw)

Last Updated : 30 May, 2022

Median is often referred to as the robust measure of the central location and is less affected by the presence of outliers in data. statistics module in Python allows three options to deal with median / middle elements in a data set, which are median(), median_low() and median_high(). The low median is always a member of the data set. When the number of data points is odd, the middle value is returned. When it is even, the smaller of the two middle values is returned. Let's see how median_low() works.

Syntax : median_low( [data-set] )

Parameters : [data-set] : Takes in a list, tuple or an iterable set of numeric data.

Returntype : Returns the low median of numeric data. Low median is a member of actual data-set.

Exceptions : StatisticsError is raised when data-set is empty.

Code #1 : Working

Python3 `

Python code to demonstrate the

working of median_low()

importing the statistics module

import statistics

simple list of a set of integers

set1 = [1, 3, 3, 4, 5, 7]

Note: low median will always be

a member of the data-set.

Print low median of the data-set

print("Low median of the data-set is % s " % (statistics.median_low(set1)))

`

Output :

Low median of the data-set is 3

Code #2 : Working of median_low() and median to distinguish between them.

Python3 `

Python code to demonstrate the

working of median_low()

importing the statistics module

import statistics

simple list of a set of integers

set1 = [1, 3, 3, 4, 5, 7]

Print median of the data-set

Median value may or may not

lie within the data-set

print("Median of the set is % s" % (statistics.median(set1)))

Print low median of the data-set

print("Low Median of the set is % s " % (statistics.median_low(set1)))

`

Output :

Median of the set is 3.5 Low Median of the set is 3

Code #3 : Working of median_low() on a varying range of data-set

Python3 `

Python code to demonstrate the

working of median_low()

importing statistics module

from statistics import median_low

Importing fractions module as fr

from fractions import Fraction as fr

tuple of positive integer numbers

data1 = (2, 3, 4, 5, 7, 9, 11)

tuple of a set of floating-point values

data2 = (2.4, 5.1, 6.7, 8.9)

tuple of a set of fractional numbers

data3 = (fr(1, 2), fr(44, 12), fr(10, 3), fr(2, 3))

tuple of a set of negative integers

data4 = (-5, -1, -12, -19, -3)

tuple of set of positive

and negative integers

data5 = (-1, -2, -3, -4, 4, 3, 2, 1)

Print low_median() of given data-sets

print("Low Median of data-set 1 is % s" % (median_low(data1))) print("Low Median of data-set 2 is % s" % (median_low(data2))) print("Low Median of data-set 3 is % s" % (median_low(data3))) print("Low Median of data-set 4 is % s" % (median_low(data4))) print("Low Median of data-set 5 is % s" % (median_low(data5)))

`

Output :

Low Median of data-set 1 is 5 Low Median of data-set 2 is 5.1 Low Median of data-set 3 is 2/3 Low Median of data-set 4 is -5 Low Median of data-set 5 is -1

Code #4 : Raising StatisticsError

Python3 `

Python code to demonstrate

StatisticsError of median_low()

importing the statistics module

from statistics import median_low

creating an empty data-set

empty = []

will raise StatisticsError

print(median_low(empty))

`

Output :

Traceback (most recent call last): File "/home/5f3e758236f872d014f9d741743c30a4.py", line 10, in print(median_low(empty)) File "/usr/lib/python3.5/statistics.py", line 376, in median_low raise StatisticsError("no median for empty data") statistics.StatisticsError: no median for empty data

Applications : median_low() is used when the data is discrete and prefer median to be actual point in data rather than an extrapolated one.