stats.js

function stats(imp) {
  function compareNumbers(x, y) {
    return x - y;
  }
  return (function(exports) {
    var Sequence = function(values) {
      this.sortedValues = values;
      this.sortedValues.sort(compareNumbers);
      this.quartiles = Array(5);
    };
    Sequence.prototype.min = function() {
      return this.sortedValues[0];
    };
    Sequence.prototype.max = function() {
      return this.sortedValues[this.sortedValues.length - 1];
    };
    Sequence.prototype.quartile = function(n) {
      if (n < 0 || n > 5) {
        return undefined;
      }
      if (!this.quartiles[n]) {
        var p = n / 4;
        var q = (this.sortedValues.length - 1) * p;
        var r = Math.floor(q);
        var s = q - r;
        if (this.sortedValues[r + 1] !== undefined) {
          this.quartiles[n] = this.sortedValues[r] + s * (this.sortedValues[r + 1] - this.sortedValues[r]);
        } else {
          this.quartiles[n] = this.sortedValues[r];
        }
      }
      return this.quartiles[n];
    };
    Sequence.prototype.iqr = function() {
      var t = this.quartile(3),
          f = this.quartile(1);
      return t - f;
    };
    
    function _Arrays_isMatrix(mat) {
      return Array.isArray(mat) && mat.every(function(vec) {
        return Array.isArray(vec) && vec.length === mat[0].length;
      });
    }
    function _Arrays_take(n) {
      return function(arr) {
        return arr.slice(0, n);
      };
    }
    function _Arrays_get(n) {
      return function(arr) {
        return arr[n];
      };
    }
    
    function Range(x, y) {
      if (y === undefined) {
        this.l = 0;
        this.u = x;
      } else {
        this.l = x;
        this.u = y;
      }
    };
    Range.prototype.forEach = function(cb) {
      for (var n = this.l; n < this.u; n++) {
        var idx = n - this.l;
        cb(n, idx);
      }
    };
    Range.prototype.map = function(cb) {
      var result = [];
      for (var n = this.l; n < this.u; n++) {
        var idx = n - this.l;
        result.push(cb(n, idx));
      }
      return result;
    };
    
    exports.Sequence = Sequence;
    exports.Range = Range;
    exports.Arrays = {
      isMatrix: _Arrays_isMatrix,
      take: _Arrays_take,
      get: _Arrays_get
    };
  })(imp);
}

function import(modl) {
  modl(this);
}

function IQR(values) {
  import(stats);

  if (Arrays.isMatrix(values)) {
    var range = new Range(values[0].length);
    return [range.map(function(n) {
      var seq = new Sequence(values.map(Arrays.get(n)));
      return seq.iqr();
    })];
  } else if (Array.isArray(values) && values.length === 1) {
    var seq = new Sequence(values[0]);
    return seq.iqr();
  } else {
    return undefined;
  }
}