smooth.js

// Generated by CoffeeScript 1.6.3

/*
Smooth.js version 0.1.7

Turn arrays into smooth functions.

Copyright 2012 Spencer Cohen
Licensed under MIT license (see "Smooth.js MIT license.txt")
*/


/*Constants (these are accessible by Smooth.WHATEVER in user space)*/

(function() {
  var AbstractInterpolator, CubicInterpolator, Enum, LinearInterpolator, NearestInterpolator, PI, SincFilterInterpolator, Smooth, clipClamp, clipMirror, clipPeriodic, defaultConfig, getColumn, getType, isValidNumber, k, makeLanczosWindow, makeScaledFunction, makeSincKernel, normalizeScaleTo, shallowCopy, sin, sinc, v, validateNumber, validateVector, _ref, _ref1,
    __hasProp = {}.hasOwnProperty,
    __extends = function(child, parent) { for (var key in parent) { if (__hasProp.call(parent, key)) child[key] = parent[key]; } function ctor() { this.constructor = child; } ctor.prototype = parent.prototype; child.prototype = new ctor(); child.__super__ = parent.prototype; return child; };

  Enum = {

    /*Interpolation methods*/
    METHOD_NEAREST: 'nearest',
    METHOD_LINEAR: 'linear',
    METHOD_CUBIC: 'cubic',
    METHOD_LANCZOS: 'lanczos',
    METHOD_SINC: 'sinc',

    /*Input clipping modes*/
    CLIP_CLAMP: 'clamp',
    CLIP_ZERO: 'zero',
    CLIP_PERIODIC: 'periodic',
    CLIP_MIRROR: 'mirror',

    /* Constants for control over the cubic interpolation tension*/
    CUBIC_TENSION_DEFAULT: 0,
    CUBIC_TENSION_CATMULL_ROM: 0
  };

  defaultConfig = {
    method: Enum.METHOD_CUBIC,
    cubicTension: Enum.CUBIC_TENSION_DEFAULT,
    clip: Enum.CLIP_CLAMP,
    scaleTo: 0,
    sincFilterSize: 2,
    sincWindow: void 0
  };


  /*Index clipping functions*/

  clipClamp = function(i, n) {
    return Math.max(0, Math.min(i, n - 1));
  };

  clipPeriodic = function(i, n) {
    i = i % n;
    if (i < 0) {
      i += n;
    }
    return i;
  };

  clipMirror = function(i, n) {
    var period;
    period = 2 * (n - 1);
    i = clipPeriodic(i, period);
    if (i > n - 1) {
      i = period - i;
    }
    return i;
  };


  /*
  Abstract scalar interpolation class which provides common functionality for all interpolators
  
  Subclasses must override interpolate().
  */

  AbstractInterpolator = (function() {
    function AbstractInterpolator(array, config) {
      this.array = array.slice(0);
      this.length = this.array.length;
      if (!(this.clipHelper = {
        clamp: this.clipHelperClamp,
        zero: this.clipHelperZero,
        periodic: this.clipHelperPeriodic,
        mirror: this.clipHelperMirror
      }[config.clip])) {
        throw "Invalid clip: " + config.clip;
      }
    }

    AbstractInterpolator.prototype.getClippedInput = function(i) {
      if ((0 <= i && i < this.length)) {
        return this.array[i];
      } else {
        return this.clipHelper(i);
      }
    };

    AbstractInterpolator.prototype.clipHelperClamp = function(i) {
      return this.array[clipClamp(i, this.length)];
    };

    AbstractInterpolator.prototype.clipHelperZero = function(i) {
      return 0;
    };

    AbstractInterpolator.prototype.clipHelperPeriodic = function(i) {
      return this.array[clipPeriodic(i, this.length)];
    };

    AbstractInterpolator.prototype.clipHelperMirror = function(i) {
      return this.array[clipMirror(i, this.length)];
    };

    AbstractInterpolator.prototype.interpolate = function(t) {
      throw 'Subclasses of AbstractInterpolator must override the interpolate() method.';
    };

    return AbstractInterpolator;

  })();

  NearestInterpolator = (function(_super) {
    __extends(NearestInterpolator, _super);

    function NearestInterpolator() {
      _ref = NearestInterpolator.__super__.constructor.apply(this, arguments);
      return _ref;
    }

    NearestInterpolator.prototype.interpolate = function(t) {
      return this.getClippedInput(Math.round(t));
    };

    return NearestInterpolator;

  })(AbstractInterpolator);

  LinearInterpolator = (function(_super) {
    __extends(LinearInterpolator, _super);

    function LinearInterpolator() {
      _ref1 = LinearInterpolator.__super__.constructor.apply(this, arguments);
      return _ref1;
    }

    LinearInterpolator.prototype.interpolate = function(t) {
      var k;
      k = Math.floor(t);
      t -= k;
      return (1 - t) * this.getClippedInput(k) + t * this.getClippedInput(k + 1);
    };

    return LinearInterpolator;

  })(AbstractInterpolator);

  CubicInterpolator = (function(_super) {
    __extends(CubicInterpolator, _super);

    function CubicInterpolator(array, config) {
      this.tangentFactor = 1 - Math.max(0, Math.min(1, config.cubicTension));
      CubicInterpolator.__super__.constructor.apply(this, arguments);
    }

    CubicInterpolator.prototype.getTangent = function(k) {
      return this.tangentFactor * (this.getClippedInput(k + 1) - this.getClippedInput(k - 1)) / 2;
    };

    CubicInterpolator.prototype.interpolate = function(t) {
      var k, m, p, t2, t3;
      k = Math.floor(t);
      m = [this.getTangent(k), this.getTangent(k + 1)];
      p = [this.getClippedInput(k), this.getClippedInput(k + 1)];
      t -= k;
      t2 = t * t;
      t3 = t * t2;
      return (2 * t3 - 3 * t2 + 1) * p[0] + (t3 - 2 * t2 + t) * m[0] + (-2 * t3 + 3 * t2) * p[1] + (t3 - t2) * m[1];
    };

    return CubicInterpolator;

  })(AbstractInterpolator);

  sin = Math.sin, PI = Math.PI;

  sinc = function(x) {
    if (x === 0) {
      return 1;
    } else {
      return sin(PI * x) / (PI * x);
    }
  };

  makeLanczosWindow = function(a) {
    return function(x) {
      return sinc(x / a);
    };
  };

  makeSincKernel = function(window) {
    return function(x) {
      return sinc(x) * window(x);
    };
  };

  SincFilterInterpolator = (function(_super) {
    __extends(SincFilterInterpolator, _super);

    function SincFilterInterpolator(array, config) {
      SincFilterInterpolator.__super__.constructor.apply(this, arguments);
      this.a = config.sincFilterSize;
      if (!config.sincWindow) {
        throw 'No sincWindow provided';
      }
      this.kernel = makeSincKernel(config.sincWindow);
    }

    SincFilterInterpolator.prototype.interpolate = function(t) {
      var k, n, sum, _i, _ref2, _ref3;
      k = Math.floor(t);
      sum = 0;
      for (n = _i = _ref2 = k - this.a + 1, _ref3 = k + this.a; _ref2 <= _ref3 ? _i <= _ref3 : _i >= _ref3; n = _ref2 <= _ref3 ? ++_i : --_i) {
        sum += this.kernel(t - n) * this.getClippedInput(n);
      }
      return sum;
    };

    return SincFilterInterpolator;

  })(AbstractInterpolator);

  getColumn = function(arr, i) {
    var row, _i, _len, _results;
    _results = [];
    for (_i = 0, _len = arr.length; _i < _len; _i++) {
      row = arr[_i];
      _results.push(row[i]);
    }
    return _results;
  };

  makeScaledFunction = function(f, baseScale, scaleRange) {
    var scaleFactor, translation;
    if (scaleRange.join === '0,1') {
      return f;
    } else {
      scaleFactor = baseScale / (scaleRange[1] - scaleRange[0]);
      translation = scaleRange[0];
      return function(t) {
        return f(scaleFactor * (t - translation));
      };
    }
  };

  getType = function(x) {
    return Object.prototype.toString.call(x).slice('[object '.length, -1);
  };

  validateNumber = function(n) {
    if (isNaN(n)) {
      throw 'NaN in Smooth() input';
    }
    if (getType(n) !== 'Number') {
      throw 'Non-number in Smooth() input';
    }
    if (!isFinite(n)) {
      throw 'Infinity in Smooth() input';
    }
  };

  validateVector = function(v, dimension) {
    var n, _i, _len;
    if (getType(v) !== 'Array') {
      throw 'Non-vector in Smooth() input';
    }
    if (v.length !== dimension) {
      throw 'Inconsistent dimension in Smooth() input';
    }
    for (_i = 0, _len = v.length; _i < _len; _i++) {
      n = v[_i];
      validateNumber(n);
    }
  };

  isValidNumber = function(n) {
    return (getType(n) === 'Number') && isFinite(n) && !isNaN(n);
  };

  normalizeScaleTo = function(s) {
    var invalidErr;
    invalidErr = "scaleTo param must be number or array of two numbers";
    switch (getType(s)) {
      case 'Number':
        if (!isValidNumber(s)) {
          throw invalidErr;
        }
        s = [0, s];
        break;
      case 'Array':
        if (s.length !== 2) {
          throw invalidErr;
        }
        if (!(isValidNumber(s[0]) && isValidNumber(s[1]))) {
          throw invalidErr;
        }
        break;
      default:
        throw invalidErr;
    }
    return s;
  };

  shallowCopy = function(obj) {
    var copy, k, v;
    copy = {};
    for (k in obj) {
      if (!__hasProp.call(obj, k)) continue;
      v = obj[k];
      copy[k] = v;
    }
    return copy;
  };

  Smooth = function(arr, config) {
    var baseDomainEnd, dimension, i, interpolator, interpolatorClass, interpolators, k, n, properties, smoothFunc, v;
    if (config == null) {
      config = {};
    }
    properties = {};
    config = shallowCopy(config);
    properties.config = shallowCopy(config);
    if (config.scaleTo == null) {
      config.scaleTo = config.period;
    }
    if (config.sincFilterSize == null) {
      config.sincFilterSize = config.lanczosFilterSize;
    }
    for (k in defaultConfig) {
      if (!__hasProp.call(defaultConfig, k)) continue;
      v = defaultConfig[k];
      if (config[k] == null) {
        config[k] = v;
      }
    }
    if (!(interpolatorClass = {
      nearest: NearestInterpolator,
      linear: LinearInterpolator,
      cubic: CubicInterpolator,
      lanczos: SincFilterInterpolator,
      sinc: SincFilterInterpolator
    }[config.method])) {
      throw "Invalid method: " + config.method;
    }
    if (config.method === 'lanczos') {
      config.sincWindow = makeLanczosWindow(config.sincFilterSize);
    }
    if (arr.length < 2) {
      throw 'Array must have at least two elements';
    }
    properties.count = arr.length;
    smoothFunc = (function() {
      var _i, _j, _len, _len1;
      switch (getType(arr[0])) {
        case 'Number':
          properties.dimension = 'scalar';
          if (Smooth.deepValidation) {
            for (_i = 0, _len = arr.length; _i < _len; _i++) {
              n = arr[_i];
              validateNumber(n);
            }
          }
          interpolator = new interpolatorClass(arr, config);
          return function(t) {
            return interpolator.interpolate(t);
          };
        case 'Array':
          properties.dimension = dimension = arr[0].length;
          if (!dimension) {
            throw 'Vectors must be non-empty';
          }
          if (Smooth.deepValidation) {
            for (_j = 0, _len1 = arr.length; _j < _len1; _j++) {
              v = arr[_j];
              validateVector(v, dimension);
            }
          }
          interpolators = (function() {
            var _k, _results;
            _results = [];
            for (i = _k = 0; 0 <= dimension ? _k < dimension : _k > dimension; i = 0 <= dimension ? ++_k : --_k) {
              _results.push(new interpolatorClass(getColumn(arr, i), config));
            }
            return _results;
          })();
          return function(t) {
            var _k, _len2, _results;
            _results = [];
            for (_k = 0, _len2 = interpolators.length; _k < _len2; _k++) {
              interpolator = interpolators[_k];
              _results.push(interpolator.interpolate(t));
            }
            return _results;
          };
        default:
          throw "Invalid element type: " + (getType(arr[0]));
      }
    })();
    if (config.clip === 'periodic') {
      baseDomainEnd = arr.length;
    } else {
      baseDomainEnd = arr.length - 1;
    }
    config.scaleTo || (config.scaleTo = baseDomainEnd);
    properties.domain = normalizeScaleTo(config.scaleTo);
    smoothFunc = makeScaledFunction(smoothFunc, baseDomainEnd, properties.domain);
    properties.domain.sort();

    /*copy properties*/
    for (k in properties) {
      if (!__hasProp.call(properties, k)) continue;
      v = properties[k];
      smoothFunc[k] = v;
    }
    return smoothFunc;
  };

  for (k in Enum) {
    if (!__hasProp.call(Enum, k)) continue;
    v = Enum[k];
    Smooth[k] = v;
  }

  Smooth.deepValidation = true;

  (typeof exports !== "undefined" && exports !== null ? exports : window).Smooth = Smooth;

}).call(this);