/**
* Copyright (c) 2009 - 2010 Chris Leonello
* jqPlot is currently available for use in all personal or commercial projects
* under both the MIT and GPL version 2.0 licenses. This means that you can
* choose the license that best suits your project and use it accordingly.
*
* The author would appreciate an email letting him know of any substantial
* use of jqPlot. You can reach the author at: chris at jqplot dot com
* or see http://www.jqplot.com/info.php . This is, of course,
* not required.
*
* If you are feeling kind and generous, consider supporting the project by
* making a donation at: http://www.jqplot.com/donate.php .
*
* Thanks for using jqPlot!
*
*/
(function($) {
/**
* Class: $.jqplot.Trendline
* Plugin which will automatically compute and draw trendlines for plotted data.
*/
$.jqplot.Trendline = function() {
// Group: Properties
// prop: show
// Wether or not to show the trend line.
this.show = $.jqplot.config.enablePlugins;
// prop: color
// CSS color spec for the trend line.
// By default this wil be the same color as the primary line.
this.color = '#666666';
// prop: renderer
// Renderer to use to draw the trend line.
// The data series that is plotted may not be rendered as a line.
// Therefore, we use our own line renderer here to draw a trend line.
this.renderer = new $.jqplot.LineRenderer();
// prop: rendererOptions
// Options to pass to the line renderer.
// By default, markers are not shown on trend lines.
this.rendererOptions = {marker:{show:false}};
// prop: label
// Label for the trend line to use in the legend.
this.label = '';
// prop: type
// Either 'exponential', 'exp', or 'linear'.
this.type = 'linear';
// prop: shadow
// true or false, wether or not to show the shadow.
this.shadow = true;
// prop: markerRenderer
// Renderer to use to draw markers on the line.
// I think this is wrong.
this.markerRenderer = {show:false};
// prop: lineWidth
// Width of the trend line.
this.lineWidth = 1.5;
// prop: shadowAngle
// Angle of the shadow on the trend line.
this.shadowAngle = 45;
// prop: shadowOffset
// pixel offset for each stroke of the shadow.
this.shadowOffset = 1.0;
// prop: shadowAlpha
// Alpha transparency of the shadow.
this.shadowAlpha = 0.07;
// prop: shadowDepth
// number of strokes to make of the shadow.
this.shadowDepth = 3;
this.isTrendline = true;
};
$.jqplot.postSeriesInitHooks.push(parseTrendLineOptions);
$.jqplot.postDrawSeriesHooks.push(drawTrendline);
$.jqplot.addLegendRowHooks.push(addTrendlineLegend);
// called witin scope of the legend object
// current series passed in
// must return null or an object {label:label, color:color}
function addTrendlineLegend(series) {
var lt = series.trendline.label.toString();
var ret = null;
if (this.renderer.constructor != $.jqplot.PieRenderer && series.trendline.show && lt) {
ret = {label:lt, color:series.trendline.color};
}
return ret;
}
// called within scope of a series
function parseTrendLineOptions (target, data, seriesDefaults, options, plot) {
if (this.renderer.constructor == $.jqplot.LineRenderer) {
this.trendline = new $.jqplot.Trendline();
options = options || {};
$.extend(true, this.trendline, {color:this.color}, seriesDefaults.trendline, options.trendline);
this.trendline.renderer.init.call(this.trendline, null);
}
}
// called within scope of series object
function drawTrendline(sctx, options) {
// if we have options, merge trendline options in with precedence
options = $.extend(true, {}, this.trendline, options);
if (options.show && this.renderer.constructor != $.jqplot.PieRenderer) {
var fit;
// this.renderer.setGridData.call(this);
var data = options.data || this.data;
fit = fitData(data, this.trendline.type);
var gridData = options.gridData || this.renderer.makeGridData.call(this, fit.data);
this.trendline.renderer.draw.call(this.trendline, sctx, gridData, {showLine:true, shadow:this.trendline.shadow});
}
}
function regression(x, y, typ) {
var type = (typ == null) ? 'linear' : typ;
var N = x.length;
var slope;
var intercept;
var SX = 0;
var SY = 0;
var SXX = 0;
var SXY = 0;
var SYY = 0;
var Y = [];
var X = [];
if (type == 'linear') {
X = x;
Y = y;
}
else if (type == 'exp' || type == 'exponential') {
for ( var i=0; i<y.length; i++) {
// ignore points <= 0, log undefined.
if (y[i] <= 0) {
N--;
}
else {
X.push(x[i]);
Y.push(Math.log(y[i]));
}
}
}
for ( var i = 0; i < N; i++) {
SX = SX + X[i];
SY = SY + Y[i];
SXY = SXY + X[i]* Y[i];
SXX = SXX + X[i]* X[i];
SYY = SYY + Y[i]* Y[i];
}
slope = (N*SXY - SX*SY)/(N*SXX - SX*SX);
intercept = (SY - slope*SX)/N;
return [slope, intercept];
}
function linearRegression(X,Y) {
var ret;
ret = regression(X,Y,'linear');
return [ret[0],ret[1]];
}
function expRegression(X,Y) {
var ret;
var x = X;
var y = Y;
ret = regression(x, y,'exp');
var base = Math.exp(ret[0]);
var coeff = Math.exp(ret[1]);
return [base, coeff];
}
function fitData(data, typ) {
var type = (typ == null) ? 'linear' : typ;
var ret;
var res;
var x = [];
var y = [];
var ypred = [];
for (i=0; i<data.length; i++){
if (data[i] != null && data[i][0] != null && data[i][1] != null) {
x.push(data[i][0]);
y.push(data[i][1]);
}
}
if (type == 'linear') {
ret = linearRegression(x,y);
for ( var i=0; i<x.length; i++){
res = ret[0]*x[i] + ret[1];
ypred.push([x[i], res]);
}
}
else if (type == 'exp' || type == 'exponential') {
ret = expRegression(x,y);
for ( var i=0; i<x.length; i++){
res = ret[1]*Math.pow(ret[0],x[i]);
ypred.push([x[i], res]);
}
}
return {data: ypred, slope: ret[0], intercept: ret[1]};
}
})(jQuery);