simple-statistics/src/subtract_from_mean.js

Simple Statistics

/**
 * When removing a value from a list, one does not have to necessary
 * recompute the mean of the list in linear time. They can instead use
 * this function to compute the new mean by providing the current mean,
 * the number of elements in the list that produced it and the value to remove.
 *
 * @since 3.0.0
 * @param {number} mean current mean
 * @param {number} n number of items in the list
 * @param {number} value the value to remove
 * @returns {number} the new mean
 *
 * @example
 * subtractFromMean(20.5, 6, 53); // => 14
 */
function subtractFromMean(mean, n, value) {
    return (mean * n - value) / (n - 1);
}

export default subtractFromMean;