# Python | Variance of List

• Last Updated : 17 Sep, 2019

While working with Python, we can have a problem in which we need to find variance of a list cumulative. This problem is common in Data Science domain. Let’s discuss certain ways in which this problem can be solved.

Method #1 : Using loop + formula
The simpler manner to approach this problem is to employ the formula for finding variance and perform using loop shorthands. This is the most basic approach to solve this problem.

 `# Python3 code to demonstrate working of``# Variance of List``# using loop + formula`` ` `# initialize list``test_list ``=` `[``6``, ``7``, ``3``, ``9``, ``10``, ``15``]`` ` `# printing original list``print``(``"The original list is : "` `+` `str``(test_list))`` ` `# Variance of List``# using loop + formula``mean ``=` `sum``(test_list) ``/` `len``(test_list)``res ``=` `sum``((i ``-` `mean) ``*``*` `2` `for` `i ``in` `test_list) ``/` `len``(test_list)`` ` `# printing result``print``(``"The variance of list is : "` `+` `str``(res))`

Output :

```The original list is : [6, 7, 3, 9, 10, 15]
The variance of list is : 13.888888888888891
```

Method #2 : Using `statistics.variance()`
This task can also be performed using inbuilt function of `variance()`.

 `# Python3 code to demonstrate working of``# Variance of List``# using statistics.variance``import` `statistics `` ` `# initialize list``test_list ``=` `[``6``, ``7``, ``3``, ``9``, ``10``, ``15``]`` ` `# printing original list``print``(``"The original list is : "` `+` `str``(test_list))`` ` `# Variance of List``# using statistics.variance``res ``=` `statistics.variance(test_list)`` ` `# printing result``print``(``"The variance of list is : "` `+` `str``(res))`

Output :

```The original list is : [6, 7, 3, 9, 10, 15]
The variance of list is : 13.888888888888891
```

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