Statistical Functions in Python | Set 2 ( Measure of Spread)

Datetime:2016-08-23 01:04:46          Topic: Python           Share

Statistical Functions in Python | Set 1(Averages and Measure of Central Location)

Measure of spread functions of statistics are discussed in this article.

1. variance():- This function calculates the variance i.e measure of deviation of data, more the value of variance, more the data values are spread . Sample variance is computed in this function, assuming data is of a part of population. If passed argument is empty, StatisticsError is raised.

2. pvariance():- This function computes the variance of the entire population . The data is interpreted as it is of the whole population. If passed argument is empty, StatisticsError is raised.

# Python code to demonstrate the working of 
# variance() and pvariance()

# importing statistics to handle statistical operations
import statistics

# initializing list
li = [1.5, 2.5, 2.5, 3.5, 3.5, 3.5]

# using variance to calculate variance of data
print ("The variance of data is : ",end="")
print (statistics.variance(li))

# using pvariance to calculate population variance of data
print ("The population variance of data is : ",end="")
print (statistics.pvariance(li))

Output:

The variance of data is : 0.6666666666666667
The population variance of data is : 0.5555555555555556

3. stdev():- This function returns the standard deviation ( square root of sample variance ) of the data. If passed argument is empty, StatisticsError is raised.

4. pstdev():- This function returns the population standard deviation ( square root of population variance ) of the data. If passed argument is empty, StatisticsError is raised.

# Python code to demonstrate the working of 
# stdev() and pstdev()

# importing statistics to handle statistical operations
import statistics

# initializing list
li = [1.5, 2.5, 2.5, 3.5, 3.5, 3.5]

# using stdev to calculate standard deviation of data
print ("The standard deviation of data is : ",end="")
print (statistics.stdev(li))

# using pstdev to calculate population standard deviation of data
print ("The population standard deviation of data is : ",end="")
print (statistics.pstdev(li))

Output:

The standard deviation of data is : 0.816496580927726
The population standard deviation of data is : 0.7453559924999299

This article is contributed by Manjeet Singh . If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.

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