# Simple Statistics snippet

JS函数式编程计算标准差

```
const sample = [];
const mean = sample.reduce((x, y) => x + y)/sample.length;
const deviation = sample.map((x) => x - mean);
const std_deviation = Math.sqrt(
deviation
.map((x) => x*x)
.reduce((x,y) => x + y) / (sample.length-1)
);
```