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| author | Tristan Zur <tzur@web.web.ccwn.org> | 2014-03-27 22:27:47 +0100 |
|---|---|---|
| committer | Tristan Zur <tzur@web.web.ccwn.org> | 2014-03-27 22:27:47 +0100 |
| commit | b62676ca5d3d6f6ba3f019ea3f99722e165a98d8 (patch) | |
| tree | 86722cb80f07d4569f90088eeaea2fc2f6e2ef94 /js/dojo-1.7.2/dojox/math/stats.js | |
Diffstat (limited to 'js/dojo-1.7.2/dojox/math/stats.js')
| -rw-r--r-- | js/dojo-1.7.2/dojox/math/stats.js | 195 |
1 files changed, 195 insertions, 0 deletions
diff --git a/js/dojo-1.7.2/dojox/math/stats.js b/js/dojo-1.7.2/dojox/math/stats.js new file mode 100644 index 0000000..ddb756b --- /dev/null +++ b/js/dojo-1.7.2/dojox/math/stats.js @@ -0,0 +1,195 @@ +//>>built +// AMD-ID "dojox/math/stats" +define("dojox/math/stats", ["dojo", "../main"], function(dojo, dojox) { + + dojo.getObject("math.stats", true, dojox); + + var st = dojox.math.stats; + dojo.mixin(st, { + sd: function(/* Number[] */a){ + // summary: + // Returns the standard deviation of the passed arguments. + return Math.sqrt(st.variance(a)); // Number + }, + + variance: function(/* Number[] */a){ + // summary: + // Find the variance in the passed array of numbers. + var mean=0, squares=0; + dojo.forEach(a, function(item){ + mean+=item; + squares+=Math.pow(item,2); + }); + return (squares/a.length)-Math.pow(mean/a.length, 2); // Number + }, + + bestFit: function(/* Object[] || Number[] */a, /* String? */xProp, /* String? */yProp){ + // summary: + // Calculate the slope and intercept in a linear fashion. An array + // of objects is expected; optionally you can pass in the property + // names for "x" and "y", else x/y is used as the default. If you + // pass an array of numbers, it will be mapped to a set of {x,y} objects + // where x = the array index. + xProp = xProp || "x", yProp = yProp || "y"; + if(a[0] !== undefined && typeof(a[0]) == "number"){ + // this is an array of numbers, so use the index as x. + a = dojo.map(a, function(item, idx){ + return { x: idx, y: item }; + }); + } + + var sx = 0, sy = 0, sxx = 0, syy = 0, sxy = 0, stt = 0, sts = 0, n = a.length, t; + for(var i=0; i<n; i++){ + sx += a[i][xProp]; + sy += a[i][yProp]; + sxx += Math.pow(a[i][xProp], 2); + syy += Math.pow(a[i][yProp], 2); + sxy += a[i][xProp] * a[i][yProp]; + } + + // we use the following because it's more efficient and accurate for determining the slope. + for(i=0; i<n; i++){ + t = a[i][xProp] - sx/n; + stt += t*t; + sts += t*a[i][yProp]; + } + var slope = sts/(stt||1); // prevent divide by zero. + + // get Pearson's R + var d = Math.sqrt((sxx - Math.pow(sx,2)/n) * (syy - Math.pow(sy,2)/n)); + if(d === 0){ + throw new Error("dojox.math.stats.bestFit: the denominator for Pearson's R is 0."); + } + + var r = (sxy-(sx*sy/n)) / d; + var r2 = Math.pow(r, 2); + if(slope < 0){ + r = -r; + } + + // to use: y = slope*x + intercept; + return { // Object + slope: slope, + intercept: (sy - sx*slope)/(n||1), + r: r, + r2: r2 + }; + }, + + forecast: function(/* Object[] || Number[] */a, /* Number */x, /* String? */xProp, /* String? */yProp){ + // summary: + // Using the bestFit algorithm above, find y for the given x. + var fit = st.bestFit(a, xProp, yProp); + return (fit.slope * x) + fit.intercept; // Number + }, + + mean: function(/* Number[] */a){ + // summary: + // Returns the mean value in the passed array. + var t=0; + dojo.forEach(a, function(v){ + t += v; + }); + return t / Math.max(a.length, 1); // Number + }, + + min: function(/* Number[] */a){ + // summary: + // Returns the min value in the passed array. + return Math.min.apply(null, a); // Number + }, + + max: function(/* Number[] */a){ + // summary: + // Returns the max value in the passed array. + return Math.max.apply(null, a); // Number + }, + + median: function(/* Number[] */a){ + // summary: + // Returns the value closest to the middle from a sorted version of the passed array. + var t = a.slice(0).sort(function(a, b){ return a - b; }); + return (t[Math.floor(a.length/2)] + t[Math.ceil(a.length/2)])/2; // Number + }, + + mode: function(/* Number[] */a){ + // summary: + // Returns the mode from the passed array (number that appears the most often). + // This is not the most efficient method, since it requires a double scan, but + // is ensures accuracy. + var o = {}, r = 0, m = Number.MIN_VALUE; + dojo.forEach(a, function(v){ + (o[v]!==undefined)?o[v]++:o[v]=1; + }); + + // we did the lookup map because we need the number that appears the most. + for(var p in o){ + if(m < o[p]){ + m = o[p], r = p; + } + } + return r; // Number + }, + + sum: function(/* Number[] */a){ + // summary: + // Return the sum of all the numbers in the passed array. Does + // not check to make sure values within a are NaN (should simply + // return NaN). + var sum = 0; + dojo.forEach(a, function(n){ + sum += n; + }); + return sum; // Number + }, + + approxLin: function(a, pos){ + // summary: + // Returns a linearly approximated value from an array using + // a normalized float position value. + // a: Number[]: + // a sorted numeric array to be used for the approximation. + // pos: Number: + // a position number from 0 to 1. If outside of this range it + // will be clamped. + // returns: Number + var p = pos * (a.length - 1), t = Math.ceil(p), f = t - 1; + if(f < 0){ return a[0]; } + if(t >= a.length){ return a[a.length - 1]; } + return a[f] * (t - p) + a[t] * (p - f); // Number + }, + + summary: function(a, alreadySorted){ + // summary: + // Returns a non-parametric collection of summary statistics: + // the classic five-number summary extended to the Bowley's + // seven-figure summary. + // a: Number[]: + // a numeric array to be appraised. + // alreadySorted: Boolean?: + // a Boolean flag to indicated that the array is already sorted. + // This is an optional flag purely to improve the performance. + // If skipped, the array will be assumed unsorted. + // returns: Object + if(!alreadySorted){ + a = a.slice(0); // copy the array + a.sort(function(a, b){ return a - b; }); // sort it properly + } + var l = st.approxLin, + result = { + // the five-number summary + min: a[0], // minimum + p25: l(a, 0.25), // lower quartile + med: l(a, 0.5), // median + p75: l(a, 0.75), // upper quartile + max: a[a.length - 1], // maximum + // extended to the Bowley's seven-figure summary + p10: l(a, 0.1), // first decile + p90: l(a, 0.9) // last decile + }; + return result; // Object + } + }); + + return dojox.math.stats; +}); |
