[dygraphs.git] / tests / linear-regression.html

<html>
  <head>
    <title>Linear Regression</title>
    <!--[if IE]>
    <script type="text/javascript" src="excanvas.js"></script>
    <![endif]-->
    <script type="text/javascript" src="../strftime/strftime-min.js"></script>
    <script type="text/javascript" src="../rgbcolor/rgbcolor.js"></script>
    <script type="text/javascript" src="../dygraph-canvas.js"></script>
    <script type="text/javascript" src="../dygraph.js"></script>
    <style type="text/css">
    body { max-width: 640 px; }
    </style>
  </head>
  <body>
    <h2>Linear Regression Demo</h2>
    <p>Click the buttons to generate linear regressions over either data
    series. If you zoom in and click the regression button, the regression will
    only be run over visible points. Zoom back out to see what the local
    regression looks like over the full data.</p>

    <div id="demodiv" style="width: 480px; height: 320px;"></div>

    <script type="text/javascript">
      var data = [];
      for (var i = 0; i < 120; i++) {
        data.push([i,
                   i / 5.0 + 10.0 * Math.sin(i / 3.0),
                   30.0 - i / 5.0 - 10.0 * Math.sin(i / 3.0 + 1.0)]);
      }

      g = new Dygraph(
              document.getElementById("demodiv"),
              data,
              {
                labels: ['X', 'Y1', 'Y2'],
                underlayCallback: drawLines,
                drawPoints: true
              }
          );

      // coefficients of regression for each series.
      // if coeffs = [ null, [1, 2], null ] then we draw a regression for series 1
      // only. The regression line is y = 1 + 2 * x.
      var coeffs = [ null, null, null ];
      function regression(series) {
        // Only run the regression over visible points.
        var range = g.xAxisRange();

        var sum_xy = 0.0, sum_x = 0.0, sum_y = 0.0, sum_x2 = 0.0, num = 0;
        for (var i = 0; i < g.numRows(); i++) {
          var x = g.getValue(i, 0);
          if (x < range[0] || x > range[1]) continue;

          var y = g.getValue(i, series);
          if (y == null) continue;

          num++;
          sum_x += x;
          sum_y += y;
          sum_xy += x * y;
          sum_x2 += x * x;
        }

        var a = (sum_xy - sum_x * sum_y / num) / (sum_x2 - sum_x * sum_x / num);
        var b = (sum_y - a * sum_x) / num;

        coeffs[series] = [b, a];
        if (console) {
          console.log("coeffs(" + series + "): [" + b + ", " + a + "]");
        }

        g.updateOptions({});  // forces a redraw.
      }

      function clearLines() {
        for (var i = 0; i < coeffs.length; i++) coeffs[i] = null;
        g.updateOptions({});
      }

      function drawLines(ctx, area, layout) {
        if (typeof(g) == 'undefined') return;  // won't be set on the initial draw.

        var range = g.xAxisRange();
        for (var i = 0; i < coeffs.length; i++) {
          if (!coeffs[i]) continue;
          var a = coeffs[i][1];
          var b = coeffs[i][0];

          var x1 = range[0];
          var y1 = a * x1 + b;
          var x2 = range[1];
          var y2 = a * x2 + b;

          var p1 = g.toDomCoords(x1, y1);
          var p2 = g.toDomCoords(x2, y2);

          var color = g.getColors()[i - 1];
          ctx.save();
          ctx.strokeStyle = color;
          ctx.lineWidth = 1.0;
          ctx.beginPath();
          ctx.moveTo(p1[0], p1[1]);
          ctx.lineTo(p2[0], p2[1]);
          ctx.closePath();
          ctx.stroke();
          ctx.restore();
        }
      }
      
    </script>
    
    <div style="position: absolute; left: 500px; top: 150px;">
    <input type=button style="color: green;" value="Regression (Y1)" onClick="regression(1)" />
    <br/><br/>
    <input type=button style="color: blue;" value="Regression (Y2)" onClick="regression(2)" />
    <br/><br/>
    <input type=button value="Clear Lines" onClick="clearLines()" />
    </div>
</body>
</html>
Commit	Line	Data
05a1d116 DV	1	<html>
	2	<head>
	3	<title>Linear Regression</title>
	4	<!--[if IE]>
	5	<script type="text/javascript" src="excanvas.js"></script>
	6	<![endif]-->
	7	<script type="text/javascript" src="../strftime/strftime-min.js"></script>
	8	<script type="text/javascript" src="../rgbcolor/rgbcolor.js"></script>
	9	<script type="text/javascript" src="../dygraph-canvas.js"></script>
	10	<script type="text/javascript" src="../dygraph.js"></script>
	11	<style type="text/css">
	12	body { max-width: 640 px; }
	13	</style>
	14	</head>
	15	<body>
	16	<h2>Linear Regression Demo</h2>
	17	<p>Click the buttons to generate linear regressions over either data
	18	series. If you zoom in and click the regression button, the regression will
	19	only be run over visible points. Zoom back out to see what the local
	20	regression looks like over the full data.</p>
	21
	22	<div id="demodiv" style="width: 480px; height: 320px;"></div>
	23
	24	<script type="text/javascript">
	25	var data = [];
	26	for (var i = 0; i < 120; i++) {
	27	data.push([i,
	28	i / 5.0 + 10.0 * Math.sin(i / 3.0),
	29	30.0 - i / 5.0 - 10.0 * Math.sin(i / 3.0 + 1.0)]);
	30	}
	31
	32	g = new Dygraph(
	33	document.getElementById("demodiv"),
	34	data,
	35	{
	36	labels: ['X', 'Y1', 'Y2'],
	37	underlayCallback: drawLines,
	38	drawPoints: true
	39	}
	40	);
	41
	42	// coefficients of regression for each series.
	43	// if coeffs = [ null, [1, 2], null ] then we draw a regression for series 1
	44	// only. The regression line is y = 1 + 2 * x.
	45	var coeffs = [ null, null, null ];
	46	function regression(series) {
	47	// Only run the regression over visible points.
	48	var range = g.xAxisRange();
	49
	50	var sum_xy = 0.0, sum_x = 0.0, sum_y = 0.0, sum_x2 = 0.0, num = 0;
	51	for (var i = 0; i < g.numRows(); i++) {
	52	var x = g.getValue(i, 0);
	53	if (x < range[0] \|\| x > range[1]) continue;
	54
	55	var y = g.getValue(i, series);
	56	if (y == null) continue;
	57
	58	num++;
	59	sum_x += x;
	60	sum_y += y;
	61	sum_xy += x * y;
	62	sum_x2 += x * x;
	63	}
	64
65	var a = (sum_xy - sum_x * sum_y / num) / (sum_x2 - sum_x * sum_x / num);
66	var b = (sum_y - a * sum_x) / num;
67
68	coeffs[series] = [b, a];
2a07b0ad DV	69	if (console) {
	70	console.log("coeffs(" + series + "): [" + b + ", " + a + "]");
	71	}
05a1d116 DV	72
	73	g.updateOptions({}); // forces a redraw.
	74	}
	75
	76	function clearLines() {
	77	for (var i = 0; i < coeffs.length; i++) coeffs[i] = null;
	78	g.updateOptions({});
	79	}
	80
	81	function drawLines(ctx, area, layout) {
	82	if (typeof(g) == 'undefined') return; // won't be set on the initial draw.
	83
	84	var range = g.xAxisRange();
	85	for (var i = 0; i < coeffs.length; i++) {
	86	if (!coeffs[i]) continue;
	87	var a = coeffs[i][1];
	88	var b = coeffs[i][0];
	89
	90	var x1 = range[0];
	91	var y1 = a * x1 + b;
	92	var x2 = range[1];
	93	var y2 = a * x2 + b;
	94
	95	var p1 = g.toDomCoords(x1, y1);
	96	var p2 = g.toDomCoords(x2, y2);
	97
05a1d116 DV	98	var color = g.getColors()[i - 1];
	99	ctx.save();
	100	ctx.strokeStyle = color;
	101	ctx.lineWidth = 1.0;
	102	ctx.beginPath();
	103	ctx.moveTo(p1[0], p1[1]);
	104	ctx.lineTo(p2[0], p2[1]);
	105	ctx.closePath();
	106	ctx.stroke();
	107	ctx.restore();
	108	}
	109	}
	110
	111	</script>
	112
	113	<div style="position: absolute; left: 500px; top: 150px;">
	114	<input type=button style="color: green;" value="Regression (Y1)" onClick="regression(1)" />
	115	<br/><br/>
	116	<input type=button style="color: blue;" value="Regression (Y2)" onClick="regression(2)" />
	117	<br/><br/>
	118	<input type=button value="Clear Lines" onClick="clearLines()" />
	119	</div>
	120	</body>
	121	</html>