[removed] remove outlier from an array?

Question

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

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

Is there a library whic

Answer 1

I had some problems with the other two solutions. Problems like having NaN values as q1 and q3 because of wrong indexes. The array length needs to have an -1 because of the 0 index. Then it is checked if the index is a int or decimal, in the case of a decimal the value between two indexes is extracted.

function filterOutliers (someArray) {
    if (someArray.length < 4) {
        return someArray;
    }

    let values = someArray.slice().sort((a, b) => a - b); // copy array fast and sort

    let q1 = getQuantile(values, 25);
    let q3 = getQuantile(values, 75);

    let iqr, maxValue, minValue;
    iqr = q3 - q1;
    maxValue = q3 + iqr * 1.5;
    minValue = q1 - iqr * 1.5;

    return values.filter((x) => (x >= minValue) && (x <= maxValue));
}

function getQuantile (array, quantile) {
    // Get the index the quantile is at.
    let index = quantile / 100.0 * (array.length - 1);

    // Check if it has decimal places.
    if (index % 1 === 0) {
        return array[index];
    } else {
        // Get the lower index.
        let lowerIndex = Math.floor(index);
        // Get the remaining.
        let remainder = index - lowerIndex;
        // Add the remaining to the lowerindex value.
        return array[lowerIndex] + remainder * (array[lowerIndex + 1] - array[lowerIndex]);
    }
}