Examples of how to calculate the average (arithmetic mean) from a list of numbers in python:
Let's consider the following list
l = [5, 3, 2, 9, 1, 4]
to calculate the mean, there are several solutions:
Note: here the mean is based on the following estimator:
\begin{equation}
\hat{\mu} = \frac{1}{n} \sum x
\end{equation}
Calculate the mean with the python module statistics
To calculate the mean from a list, a solution is to use the python module statistics, example:
from statistics import mean
l_mean = mean(l)
print(l_mean)
returns
4.0
Calculate the mean with numpy
Another solution using numpy:
import numpy as np
l_mean = np.mean(np.array(l))
print(l_mean)
returns
4.0
Calculate the mean with sum() et len()
l_mean = sum(l) / len(l)
print(l_mean)
returns
4.0
Calculate the mean with a for loop
Another example using a for loop
a = 0
b = 0
for i in l:
a += i
b += 1
l_mean = float(a) / b
print(l_mean)
returns
4.0
Create a function to calculate the mean
def calculate_mean_from_list(list):
return sum(list) / len(list)
calculate_mean_from_list(l)
returns
4.0
Check that the list contains only numbers
Note: to be sure that the list contains only numbers a solution is to use the function isinstance(), illustration:
l = [i for i in l if isinstance(i, (int, float))]