Home > Web Front-end > JS Tutorial > JavaScript Fun Question: Calculating Variance

JavaScript Fun Question: Calculating Variance

黄舟
Release: 2017-01-22 14:39:03
Original
4611 people have browsed it

"Variance" is commonly used in statistics and probability theory.

Given a sequence of numbers, how to find their variance?

First, find their average, then subtract the average from each number, find their sum of squares, and finally divide by the size of the sequence to get the variance.

For example: Given a sequence, [1, 2, 2, 3].

First find the average:

(1 + 2 + 2 + 3) / 4 => 2

Then find the variance:

((( 1 - 2)^2 + (2 - 2)^2 + (2-2)^2 + (3 - 2)^2) / 4 => 0.5

Sometimes, this result will be For very long decimals, we don't need to find so many digits, just keep 3 or 4 decimal digits. At this time, we can use the toFixed method of JS to round the decimals.

var variance = function(numbers) {  
    var mean = 0;  
    var sum = 0;  
    for(var i=0;i<numbers.length;i++){  
        sum += numbers[i];  
    }  
    mean = sum / numbers.length;  
    sum = 0;  
    for(var i=0;i<numbers.length;i++){  
        sum += Math.pow(numbers[i] - mean , 2);  
    }  
    return sum / numbers.length;  
};
Copy after login

The above is an interesting JavaScript question: calculating the variance. For more related content, please pay attention to the PHP Chinese website (m.sbmmt.com)!

Related labels:
source:php.cn
Statement of this Website
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn
Popular Tutorials
More>
Latest Downloads
More>
Web Effects
Website Source Code
Website Materials
Front End Template