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# Calculate standard deviation of a dictionary in Python

• Last Updated : 31 Aug, 2021

Python dictionary is a versatile data structure that allows a lot of operations to be done without any hassle. Calculating the standard deviation is shown below.

Example #1: Using numpy.std()

First, we create a dictionary. Then we store all the values in a list by iterating over it. After this using the NumPy we calculate the standard deviation of the list.

## Python3

 # importing numpy import numpy as np       # creating our test dictionary dicti = {'a': 20, 'b': 32, 'c': 12, 'd': 93, 'e': 84}       # declaring an empty list listr = []       # appending all the values in the list for value in dicti.values():     listr.append(value)           # calculating standard deviation using np.std std = np.std(listr)       # printing results print(std)

Output:

33.63569532505609

Example #2: Using list comprehension

First, we create a list of values from the dictionary using a loop. Then we calculate mean, variance and then the standard deviation.

## Python3

 # creating our test dictionary dicti = {'a': 20, 'b': 32, 'c': 12, 'd': 93, 'e': 84}   # declaring an empty list listr = []   # appending all the values in the list for value in dicti.values():     listr.append(value)   # Standard deviation of list # Using sum() + list comprehension mean = sum(listr) / len(listr) variance = sum([((x - mean) ** 2) for x in listr]) / len(listr) res = variance ** 0.5 print(res)

Output:

33.63569532505609

Example #3: Using pstdev()

Pythons inbuilt statistics library provides a function to compute the standard deviation of a given list.

## Python3

 # importing the module import statistics   # creating the test dictionary dicti = {'a': 20, 'b': 32, 'c': 12, 'd': 93, 'e': 84}   # declaring an empty list listr = []   # appending all the values in the list for value in dicti.values():     listr.append(value)   # Standard deviation of list # Using pstdev() res = statistics.pstdev(listr) print(res)

Output

33.63569532505609

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