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94 lines
2.4 KiB
JavaScript
94 lines
2.4 KiB
JavaScript
'use strict';
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var size = require('../../utils/array').size;
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var deepForEach = require('../../utils/collection/deepForEach');
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var reduce = require('../../utils/collection/reduce');
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function factory (type, config, load, typed) {
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var add = load(require('../arithmetic/add'));
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var divide = load(require('../arithmetic/divide'));
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/**
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* Compute the mean value of matrix or a list with values.
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* In case of a multi dimensional array, the mean of the flattened array
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* will be calculated. When `dim` is provided, the maximum over the selected
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* dimension will be calculated. Parameter `dim` is zero-based.
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*
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* Syntax:
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*
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* math.mean(a, b, c, ...)
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* math.mean(A)
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* math.mean(A, dim)
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*
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* Examples:
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*
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* math.mean(2, 1, 4, 3); // returns 2.5
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* math.mean([1, 2.7, 3.2, 4]); // returns 2.725
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*
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* math.mean([[2, 5], [6, 3], [1, 7]], 0); // returns [3, 5]
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* math.mean([[2, 5], [6, 3], [1, 7]], 1); // returns [3.5, 4.5, 4]
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*
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* See also:
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*
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* median, min, max, sum, prod, std, var
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*
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* @param {... *} args A single matrix or or multiple scalar values
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* @return {*} The mean of all values
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*/
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var mean = typed('mean', {
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// mean([a, b, c, d, ...])
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'Array | Matrix': _mean,
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// mean([a, b, c, d, ...], dim)
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'Array | Matrix, number | BigNumber': _nmean,
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// mean(a, b, c, d, ...)
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'...': function () {
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return _mean(arguments);
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}
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});
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mean.toTex = '\\mathrm{${name}}\\left(${args}\\right)';
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return mean;
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/**
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* Calculate the mean value in an n-dimensional array, returning a
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* n-1 dimensional array
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* @param {Array} array
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* @param {number} dim
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* @return {number} mean
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* @private
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*/
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function _nmean(array, dim){
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var sum = reduce(array, dim, add);
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var s = Array.isArray(array) ? size(array) : array.size();
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return divide(sum, s[dim]);
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}
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/**
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* Recursively calculate the mean value in an n-dimensional array
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* @param {Array} array
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* @return {number} mean
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* @private
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*/
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function _mean(array) {
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var sum = 0;
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var num = 0;
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deepForEach(array, function (value) {
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sum = add(sum, value);
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num++;
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});
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if (num === 0) {
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throw new Error('Cannot calculate mean of an empty array');
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}
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return divide(sum, num);
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}
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}
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exports.name = 'mean';
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exports.factory = factory;
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