Created
June 5, 2012 16:00
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normal distribution thrown into scores from 0 - 100
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var scores = [0,2,3,2,24,24,2,2]; | |
//get the mean | |
var avg = 0; | |
scores.forEach(function(a) { | |
avg+= a; | |
}); | |
avg = avg / scores.length; | |
//get the standard_deviation | |
var devs = 0; | |
scores.forEach(function(a) { | |
devs += Math.pow(avg-a,2); | |
}); | |
var standard_deviation = Math.sqrt(devs/(scores.length-1)); | |
//normal distribution function | |
var normal = function(num) { | |
return (1/(standard_deviation * Math.sqrt(2*Math.PI))) * | |
Math.exp(-(Math.pow(num-avg,2)) / (2 * (Math.pow(standard_deviation,2)))); | |
} | |
//calculate the size of integral | |
var integral = 0; | |
var bar_width = standard_deviation/100; | |
for (var a=1; a<400; a++) { | |
integral += bar_width*normal(a*bar_width); | |
} | |
integral = integral*2; | |
//make the mappings from 0-100 based on the proportion of the integral | |
var mapping = {}; | |
var start = integral/2; | |
for (var a=1; a<400; a++) { | |
var proportion = Math.floor(100*(bar_width*normal(a*bar_width)+start/integral)); | |
if (!mapping[proportion]) { mapping[proportion] = a*bar_width }; | |
start += bar_width*normal(a*bar_width); | |
} | |
//bucket divisions | |
var divisions = {}; | |
for (var a in mapping) { | |
if (a == 50) { divisions[avg] = 50 } | |
else { | |
divisions[avg+mapping[a]] = parseInt(a); | |
divisions[avg-mapping[a]] = 50-(a-50); | |
} | |
} | |
var buckets= {}; | |
//now put them into buckets of 0-100 | |
var testsum = 0; | |
scores.forEach(function(a) { | |
var closest = 100000; | |
var bucket = 0; | |
for (var d in divisions) { | |
if (closest > Math.abs(a-d)) { | |
bucket = divisions[d] | |
closest = Math.abs(a-d); | |
} | |
} | |
console.log(a, bucket); | |
}); |
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