Finding the average of a list

Question

How do I find the arithmetic mean of a list in Python? For example: ``` [1, 2, 3, 4] ⟶ 2.5 ```

Accepted Answer

For Python 3.8+, use `statistics.fmean` for numerical stability with floats. (Fast.)

For Python 3.4+, use `statistics.mean` for numerical stability with floats. (Slower.)

```
xs = [15, 18, 2, 36, 12, 78, 5, 6, 9]

import statistics
statistics.mean(xs)  # = 20.11111111111111
```

For older versions of Python 3, use

```
sum(xs) / len(xs)
```

For Python 2, convert `len` to a float to get float division:

```
sum(xs) / float(len(xs))
```

Solution