Javascript:从数组中删除异常值? [英] Javascript: remove outlier from an array?

问题描述

values = [8160,8160,6160,22684,0,0,60720,1380,1380,57128]

如何删除离群值，如0、57218、60720和22684?

how can I remove outliers like 0, 57218, 60720 and 22684?

有图书馆可以做到这一点吗?

Is there a library which can do this?

推荐答案

这一切取决于您对异常值"的解释.常用方法:

This all depends on your interpretation of what an "outlier" is. A common approach:

• 离群值超出第三四分位数+ 1.5 *的值四分位间距(IQR)
• 低离群值是第一四分位数以下的任何值-1.5 * IQR

这也是 Wolfram的Mathworld 描述的方法.

这很容易包装在一个函数中:)我试图将下面的内容写清楚；确实存在明显的重构机会.请注意，使用这种常见方法，您给定的样本不包含任何异常值.

This is easily wrapped up in a function :) I've tried to write the below clearly; obvious refactoring opportunities do exist. Note that your given sample contains no outlying values using this common approach.

function filterOutliers(someArray) {  

    // Copy the values, rather than operating on references to existing values
    var values = someArray.concat();

    // Then sort
    values.sort( function(a, b) {
            return a - b;
         });

    /* Then find a generous IQR. This is generous because if (values.length / 4) 
     * is not an int, then really you should average the two elements on either 
     * side to find q1.
     */     
    var q1 = values[Math.floor((values.length / 4))];
    // Likewise for q3. 
    var q3 = values[Math.ceil((values.length * (3 / 4)))];
    var iqr = q3 - q1;

    // Then find min and max values
    var maxValue = q3 + iqr*1.5;
    var minValue = q1 - iqr*1.5;

    // Then filter anything beyond or beneath these values.
    var filteredValues = values.filter(function(x) {
        return (x <= maxValue) && (x >= minValue);
    });

    // Then return
    return filteredValues;
}

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