[dygraphs.git] / docs / index.html

<html>
  <head>
    <title>dygraphs JavaScript Library</title>
    <!--[if IE]>
    <script type="text/javascript" src="excanvas.js"></script>
    <![endif]-->
    <script type="text/javascript" src="dygraph-combined.js"></script>
    <style type="text/css">
      .thinborder {
        border-width: 1px;
        border-spacing: 0px;
        border-style: solid;
        border-color: black;
        border-collapse: collapse;
      }
      .thinborder td, .thinborder th {
        border-width: 1px;
        padding: 5px;
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      }
    </style>
  </head>
<body>
  <center>
    <p><span style="font-size:28pt;">dygraphs JavaScript Library</span><br/>
    <a href="http://code.google.com/p/dygraphs/">code.google.com/p/dygraphs</a></p>
  </center>

<p>The dygraphs JavaScript library produces produces interactive, zoomable charts of time series.</p>

<h3>Features</h3>
<ul>
  <li>Plots time series without using an external server or Flash</li>
  <li>Supports multiple data series</li>
  <li>Supports error bands around data series</li>
  <li>Displays values on mouseover</li>
  <li>Interactive zoom</li>
  <li>Adjustable averaging period</li>
  <li>Customizable click-through actions</li>
  <li>Compatible with the Google Visualization API</li>
</ul>

<h3>Caveats</h3>
<ul>
  <li>Requires Firefox 1.5+ or Safari/WebKit 1.3+.</li>
  <li>Internet Explorer is poorly supported.</li>
</ul>

<h2>Demo</h2>
<font size=-1>(Mouse over to highlight individual values. Click and drag to zoom. Double-click to zoom out.)</font><br/>
<table><tr><td>
<div id="demodiv" style="width:480px; height:320px;"></div>
</td><td valign=top>
<div id="status" style="width:200px; font-size:0.8em; padding-top:5px;"></div>
</td>
</tr></table>
<script type="text/javascript">
  g = new DateGraph(
          document.getElementById("demodiv"),
          function() {
            var zp = function(x) { if (x < 10) return "0"+x; else return x; };
            var r = "date,parabola,line,another line,sine wave\n";
            for (var i=1; i<=31; i++) {
            r += "200610" + zp(i);
            r += "," + 10*(i*(31-i));
            r += "," + 10*(8*i);
            r += "," + 10*(250 - 8*i);
            r += "," + 10*(125 + 125 * Math.sin(0.3*i));
            r += "\n";
            }
            return r;
          },
          null,
          {
            rollPeriod: 1,
            labelsDiv: document.getElementById('status'),
            labelsSeparateLines: true,
            labelsKMB: true,
            colors: ["hsl(180,60,50)",
                     "rgb(255,100,100)",
                     "#00DD55",
                     "rgba(50,50,200,0.4)"],
            padding: {left: 40, right: 30, top: 15, bottom: 15}
          }
      );
</script>

<h2>Usage</h2>

<p>The dygraphs library depends on two other JS libraries: <a href="http://www.mochikit.com/">MochiKit</a> and <a href="http://www.liquidx.net/plotkit/">PlotKit</a>. Rather than tracking down copies of these libraries, I recommend using a packed version of dygraphs that combines all three libraries into a single JS file. Either grab this file from dygraph project's <a href="http://code.google.com/p/dygraphs/downloads/list">downloads</a> page or create it yourself by <a href="http://code.google.com/p/dygraphs/source/checkout">checking out</a> a copy of the code and running:

<pre>./generate-combined.sh</pre>

<p>The combined JS file is now in <code>dygraph-combined.js</code>. Here's a basic example to get things started:</p>

<table>
  <tr><th>HTML</th>
      <td rowspan=2><img src=arrow.gif /></td>
      <th>Output</th></tr>
<tr>
<td valign=top><pre>
&lt;html&gt;
&lt;head&gt;
&lt;script type="text/javascript" src="combined.js"&gt;&lt;/script&gt;
&lt;/head&gt;
&lt;body&gt;
&lt;div id="graphdiv"&gt;&lt;/div&gt;
&lt;script type="text/javascript"&gt;
  g = new Dygraph(
        document.getElementById("graphdiv"),  // containing div
        "Date,Temperature\n" +                // CSV or path to a CSV file.
        "20080507,75\n" +
        "20080508,70\n" +
        "20080509,80\n",
      );
&lt;/script&gt;
&lt;/body&gt;
&lt;/html&gt;
</pre>
</td><td valign=top>
  <div id="graphdiv"></div>
  <script type="text/javascript">
    g = new Dygraph(
        document.getElementById("graphdiv"),  // containing div
        "Date,Temperature\n" +                // CSV or path to a CSV file.
        "20080507,75\n" +
        "20080508,70\n" +
        "20080509,80\n"
      );
  </script>
</td></tr></table>

<p>In order to keep this example self-contained, the second parameter is a function that returns CSV data. These lines <i>must</i> begin with a date in the form <i>YYYYMMDD</i>. In most applications, it makes more sense to include a CSV file instead. If the second parameter to the constructor is a string, it will be interpreted as the path to a CSV file. The Dygraph will perform an XMLHttpRequest to retrieve this file and display the data when it becomes available. Make sure your CSV file is readable and serving from a place that understands XMLHttpRequest's! In particular, you cannot specify a CSV file using <code>"file:///"</code>. Here's an example: (data from <a href="http://www.wunderground.com/history/airport/KNUQ/2007/1/1/CustomHistory.html?dayend=31&monthend=12&yearend=2007&req_city=NA&req_state=NA&req_statename=NA">Weather Underground</a>)</p>

<table>
  <tr><th>HTML</th>
      <td rowspan=2><img src=arrow.gif /></td>
      <th>Output</th></tr>
<tr>
<td valign=top><pre>
&lt;html&gt;
&lt;head&gt;
&lt;script type="text/javascript" src="combined.js"&gt;&lt;/script&gt;
&lt;/head&gt;
&lt;body&gt;
&lt;div id="graphdiv" style="width:600px; height:300px;"&gt;&lt;/div&gt;
&lt;script type="text/javascript"&gt;
  g = new Dygraph(
        document.getElementById("graphdiv"),
        "temperatures.csv",  // path to CSV file
        {}                   // additional options
      );
&lt;/script&gt;
&lt;/body&gt;
&lt;/html&gt;
</pre>
</td><td valign=top>
  <div id="graphdiv2" style="width:600px; height:300px;"></div>
  <script type="text/javascript">
    g2 = new Dygraph(
          document.getElementById("graphdiv2"),
          "temperatures.csv", {}
        );
  </script>
</td></tr></table>

<p>Click <a href="temperatures.csv">here</a> to view the <code>temperatures.csv</code> file. There are a few things to note here:</p>

<ul>
  <li>The Dygraph sent off an XHR to get the temperatures.csv file.</li>
  <li>The labels were taken from the first line of <code>temperatures.csv</code>, which is <code>Date,High,Low</code>.</li>
  <li>The Dygraph automatically chose two different, easily-distinguishable colors for the two data series.</li>
  <li>The labels on the x-axis have switched from days to months. If you zoom in, they'll switch to weeks and then days.</li>
  <li>Some heuristics are used to determine a good vertical range for the data. The idea is to make all the data visible and have human-friendly values on the axis (i.e. 200 instead of 193.4). Generally this works well.</li>
  <li>The data is very spiky. A moving average would be easier to interpret.</li>
</ul>

<p>This problem can be fixed by specifying the appropriate options in the "additional options" parameter to the Dygraph constructor. To set the number of days for a moving average, use the <b>rollPeriod</b> option. Here's how it's done:</p>

<table>
  <tr><th>HTML</th>
      <td rowspan=2><img src=arrow.gif /></td>
      <th>Output</th></tr>
<tr>
<td valign=top><pre>
&lt;html&gt;
&lt;head&gt;
&lt;script type="text/javascript" src="combined.js"&gt;&lt;/script&gt;
&lt;/head&gt;
&lt;body&gt;
&lt;div id="graphdiv" style="width:600px; height:300px;"&gt;&lt;/div&gt;
&lt;script type="text/javascript"&gt;
  g = new Dygraph(
        document.getElementById("graphdiv"),
        "temperatures.csv",
        { rollPeriod: 7,
          showRoller: true,
        }
      );
&lt;/script&gt;
&lt;/body&gt;
&lt;/html&gt;
</pre>
</td><td valign=top>
  <div id="graphdiv3" style="width:600px; height:300px;"></div>
  <script type="text/javascript">
    g3 = new Dygraph(
          document.getElementById("graphdiv3"),
          "temperatures.csv",
          { rollPeriod: 7,
            showRoller: true,
          }
        );
  </script>
</td></tr></table>

<p>A rolling average can be set using the text box in the lower left-hand corner of the graph (the showRoller attribute is what makes this appear).</p>

<h2>Error Bars</h2>
<p>Another significant feature of the dygraphs library is the ability to display error bars around data series. One standard deviation must be specified for each data point. A +/-<i>n</i> sigma band will be drawn around the data series at that point. If a moving average is being displayed, dygraphs will compute the standard deviation of the average at each point. (i.e. <i>&sigma;</i> = sqrt((<i>&sigma;_1</i>^2 + <i>&sigma;_2</i>^2 + ... + <i>&sigma;_n</i>^2)/<i>n</i>))</p>

<p>Here's a demonstration. There are two data series. One is <code>N(100,10)</code> with a standard deviation of 10 specified at each point. The other is <code>N(80,20)</code> with a standard deviation of 20 specified at each point. The CSV file was generated using Octave and can be viewed <a href="twonormals.csv">here</a>.</p>

<table>
  <tr><th>HTML</th>
      <td rowspan=2><img src=arrow.gif /></td>
      <th>Output</th></tr>
<tr>
<td valign=top><pre>
&lt;html&gt;
&lt;head&gt;
&lt;script type="text/javascript"
  src="combined.js"&gt;&lt;/script&gt;
&lt;/head&gt;
&lt;body&gt;
&lt;div id="graphdiv" 
 style="width:800px; height:400px;"
 &gt;&lt;/div&gt;
&lt;script type="text/javascript"&gt;
$ = document.getElementById;
g = new Dygraph(
  $("graphdiv"),
  "twonormals.csv",
  { rollPeriod: 7,
    showRoller: true,
    errorBars: true,
    valueRange: [50,125]
  }
);
&lt;/script&gt;
&lt;/body&gt;
&lt;/html&gt;
</pre>
</td><td valign=top>
  <div id="graphdiv4" style="width:800px; height:400px;"></div>
  <script type="text/javascript">
$ = document.getElementById;
new Dygraph(
  document.getElementById("graphdiv4"),
  "twonormals.csv",
  { rollPeriod: 14,
    showRoller: true,
    errorBars: true,
    valueRange: [50, 125]
  }
);
  </script>
</td></tr></table>

<p>Things to note here:</p>
<ul>
  <li>The <b>errorBars</b> option affects both the interpretation of the CSV file and the display of the graph. When <b>errorBars</b> is set to true, each line is interpreted as <i>YYYYMMDD</i>,<i>A</i>,<i>sigma_A</i>,<i>B</i>,<i>sigma_B</i>,...</li>
  <li>The first line of the CSV file doesn't mention the error columns. In this case, it's just "Date,Series1,Series2".</li>
  <li>The averaging visibly affects the error bars. This is most clear if you crank up the rolling period to something like 100 days. For the earliest dates, there won't be 100 data points to average so the signal will be noisier. The error bars get smaller like sqrt(N) going forward in time until there's a full 100 points to average.</li>
  <li>The error bars are partially transparent. This can be seen when they overlap one another.</li>
</ul>

<h2>One last demo</h2>

<p>This chart shows monthly closes of the Dow Jones Industrial Average, both in nominal and real (i.e. adjusted for inflation) dollars. The shaded areas show its monthly high and low. CPI values with a base from 1982-84 are used to adjust for inflation.</p>

<div id=dow_chart style="width:1000px; height:400px;"></div>
<script type="text/javascript">
  // From http://www.econstats.com/eqty/eq_d_mi_3.csv
  dow = new Dygraph(
    document.getElementById('dow_chart'),
    "dow.txt",
    {
      showRoller: true,
      customBars: true,
      labelsKMB: true,
      padding: {left:30, right:30, top:5, bottom:5}
    });
</script>


<h2>Other Options</h2>
<p>These are the options that can be passed in through the optional third parameter of the Dygraph constructor.</p>

<table class=thinborder width=1000>
  <tr><th>Name</th><th>Sample Value</th><th>Description</th></tr>
  <tr>
    <td><b>rollPeriod</b></td>
    <td><code>7</code></td>
    <td>Number of days over which to average data. Discussed extensively above.</td>
  </tr><tr>
    <td><b>showRoller</b></td>
    <td><code>true</code></td>
    <td>Should the rolling average period text box be shown? Default is false.</td>
  </tr><tr>
    <td><b>colors</b></td>
    <td><code>['red',&nbsp;'#00FF00']</code></td>
    <td>List of colors for the data series. These can be of the form "#AABBCC"
      or "rgb(255,100,200)" or "yellow", etc. If not specified, equally-spaced
      points around a color wheel are used.</td>
  </tr><tr>
    <td><b>colorSaturation</b></td>
    <td><code>1.0</code></td>
    <td>If <b>colors</b> is not specified, saturation of the
      automatically-generated data series colors. (0.0-1.0, default:
      1.0)</td>
  </tr><tr>
    <td><b>colorValue</b></td>
    <td><code>0.5</code></td>
    <td>If colors is not specified, value of the data series colors, as in
      hue/saturation/value. (0.0-1.0, default 0.5)</td>
  </tr><tr>
    <td><b>clickCallback</b></td>
    <td><code>function(e,date){ alert(date); }</code></td>
    <td>A function to call when a data point is clicked. The function should take
      two arguments, the event object for the click and the date that was
      clicked. (default null)</td>
  </tr><tr>
    <td><b>errorBars</b></td>
    <td><code>false</code></td>
    <td>Does the data contain standard deviations? Setting this to true alters
      the input format (see above). (default false)</td>
  </tr><tr>
    <td><b>strokeWidth</b></td>
    <td><code>2.0</code></td>
    <td>Width of the data lines. This can be used to increase the contrast or
      some graphs. (default 1.0)</td>
  </tr><tr>
    <td><b>dateWindow</b></td>
    <td><code>[(new&nbsp;Date('2006-01-01')).valueOf(),<br/>
        (new&nbsp;Date()).valueOf()]</code></td>
    <td>Initially zoom in on a section of the graph. Is of the form [earliest,
      latest], where earliest/latest are millis since epoch.  By default, the
      full range of the input is shown.</td>
  </tr><tr>
    <td><b>valueRange</b></td>
    <td><code>[10, 110]</code></td>
    <td>Explicitly set the vertical range of the graph to [low, high]. By
      default, some clever heuristics are used (see above).</td>
  </tr><tr>
    <td><b>minTickSize</b></td>
    <td><code>1</code</td>
    <td>The difference between ticks on the y-axis can be greater than or equal
      to this, but no less. If you set it to 1, for instance, you'll never get
      nonintegral gaps between ticks.</td>
  </tr><tr>
    <td><b>labelsSeparateLines</b></td>
    <td><code>true</code></td>
    <td>Put &lt;br/&gt; between lines in the label string. Often used in
      conjunction with <b>labelsDiv</b>. (default false)</td>
  </tr><tr>
    <td><b>labelsDiv</b></td>
    <td><code>document.getElementById('foo')</code></td>
    <td>Show data labels in an external div, rather than on the graph. (default
      null)</td>
  </tr><tr>
    <td><b>labelsKMB</b></td>
    <td><code>true</code></td>
    <td>Show K/M/B for thousands/millions/billions on y-axis (default
      false).</td>
  </tr>
  <tr>
    <td><b>padding</b></td>
    <td><code>{left:&nbsp;40, right:&nbsp;30,<br/>top:&nbsp;5,
        bottom:&nbsp;15}</code></td>
    <td>Adds extra pixels of padding around the graph. Sometimes a dygraph
      gets clipped by surrounding text (see the Demo at the top of this page).
      Setting this property appropriately will fix this problem.</td>
  </tr>
</table>

<p>Any options you specify also get passed on to PlotKit's <a href="http://media.liquidx.net/js/plotkit-doc/PlotKit.Renderer.html">Renderer</a> class. dygraphs will override some of these (e.g. strokeColor), but others may be useful. The <code>padding</code> property is an example of this.</p>

<h2>Common Gotchas</h2>
<p>Here are a few problems that I've frequently run into while using the
dygraphs library.</p>

<ul>
  <li>Make sure your CSV files are readable! If your graph isn't showing up,
  the XMLHttpRequest for the CSV file may be failing. You can determine whether
  this is the case using tools like <a
    href="http://www.getfirebug.com/">Firebug</a>.</li>

  <li>Make sure your CSV files are in the correct format. They must be of the
  form <code>YYYYMMDD,series1,series2,...</code>. And if you set the
  <code>errorBars</code> property, make sure you alternate data series and
  standard deviations.</li>

  <li>dygraphs are not happy when placed inside a <code>&lt;center&gt;</code>
  tag. This applies to the CSS <code>text-align</code> property as well. If you
  want to center a Dygraph, put it inside a table with "align=center"
  set.</li>

  <li>Don't set the <code>dateWindow</code> property to a date. It expects
  milliseconds since epoch, which can be obtained from a JavaScript Date
  object's valueOf method.</li>
</ul>

<p><font size=-1>Created May 9, 2008 by <a href=mailto:danvdk@gmail.com>Dan Vanderkam</a></font></p>

</body>
</html>
Commit	Line	Data
078d1d29 DV	1	<html>
	2	<head>
	3	<title>dygraphs JavaScript Library</title>
	4	<!--[if IE]>
	5	<script type="text/javascript" src="excanvas.js"></script>
	6	<![endif]-->
9f006dbf	7	<script type="text/javascript" src="dygraph-combined.js"></script>
078d1d29 DV	8	<style type="text/css">
	9	.thinborder {
	10	border-width: 1px;
	11	border-spacing: 0px;
	12	border-style: solid;
	13	border-color: black;
	14	border-collapse: collapse;
	15	}
	16	.thinborder td, .thinborder th {
	17	border-width: 1px;
	18	padding: 5px;
	19	border-style: solid;
	20	border-color: black;
	21	}
	22	</style>
	23	</head>
	24	<body>
	25	<center>
52e5492a DV	26	<p><span style="font-size:28pt;">dygraphs JavaScript Library</span><br/>
52e5492a DV	27	<a href="http://code.google.com/p/dygraphs/">code.google.com/p/dygraphs</a></p>
078d1d29 DV	28	</center>
078d1d29 DV	29
285a6bda	30	<p>The dygraphs JavaScript library produces produces interactive, zoomable charts of time series.</p>
078d1d29 DV	31
	32	<h3>Features</h3>
	33	<ul>
	34	<li>Plots time series without using an external server or Flash</li>
	35	<li>Supports multiple data series</li>
	36	<li>Supports error bands around data series</li>
	37	<li>Displays values on mouseover</li>
	38	<li>Interactive zoom</li>
	39	<li>Adjustable averaging period</li>
	40	<li>Customizable click-through actions</li>
285a6bda	41	<li>Compatible with the Google Visualization API</li>
078d1d29 DV	42	</ul>
	43
	44	<h3>Caveats</h3>
	45	<ul>
	46	<li>Requires Firefox 1.5+ or Safari/WebKit 1.3+.</li>
04aa50fd	47	<li>Internet Explorer is poorly supported.</li>
078d1d29 DV	48	</ul>
	49
	50	<h2>Demo</h2>
	51	<font size=-1>(Mouse over to highlight individual values. Click and drag to zoom. Double-click to zoom out.)</font><br/>
	52	<table><tr><td>
	53	<div id="demodiv" style="width:480px; height:320px;"></div>
	54	</td><td valign=top>
52e5492a	55	<div id="status" style="width:200px; font-size:0.8em; padding-top:5px;"></div>
078d1d29	56	</td>
6153f697	57	</tr></table>
078d1d29 DV	58	<script type="text/javascript">
	59	g = new DateGraph(
	60	document.getElementById("demodiv"),
	61	function() {
ca433857	62	var zp = function(x) { if (x < 10) return "0"+x; else return x; };
078d1d29 DV	63	var r = "date,parabola,line,another line,sine wave\n";
078d1d29 DV	64	for (var i=1; i<=31; i++) {
ca433857	65	r += "200610" + zp(i);
078d1d29 DV	66	r += "," + 10(i(31-i));
	67	r += "," + 10(8i);
	68	r += "," + 10(250 - 8i);
	69	r += "," + 10(125 + 125 Math.sin(0.3*i));
	70	r += "\n";
	71	}
	72	return r;
	73	},
	74	null,
	75	{
	76	rollPeriod: 1,
	77	labelsDiv: document.getElementById('status'),
	78	labelsSeparateLines: true,
	79	labelsKMB: true,
	80	colors: ["hsl(180,60,50)",
	81	"rgb(255,100,100)",
	82	"#00DD55",
	83	"rgba(50,50,200,0.4)"],
52e5492a	84	padding: {left: 40, right: 30, top: 15, bottom: 15}
078d1d29 DV	85	}
	86	);
	87	</script>
	88
	89	<h2>Usage</h2>
	90
285a6bda	91	<p>The dygraphs library depends on two other JS libraries: <a href="http://www.mochikit.com/">MochiKit</a> and <a href="http://www.liquidx.net/plotkit/">PlotKit</a>. Rather than tracking down copies of these libraries, I recommend using a packed version of dygraphs that combines all three libraries into a single JS file. Either grab this file from dygraph project's <a href="http://code.google.com/p/dygraphs/downloads/list">downloads</a> page or create it yourself by <a href="http://code.google.com/p/dygraphs/source/checkout">checking out</a> a copy of the code and running:
078d1d29	92
9f006dbf	93	<pre>./generate-combined.sh</pre>
078d1d29	94
9f006dbf	95	<p>The combined JS file is now in <code>dygraph-combined.js</code>. Here's a basic example to get things started:</p>
078d1d29 DV	96
	97	<table>
	98	<tr><th>HTML</th>
	99	<td rowspan=2><img src=arrow.gif /></td>
	100	<th>Output</th></tr>
	101	<tr>
	102	<td valign=top><pre>
	103	<html>
	104	<head>
	105	<script type="text/javascript" src="combined.js"></script>
	106	</head>
	107	<body>
285a6bda	108	<div id="graphdiv"></div>
078d1d29	109	<script type="text/javascript">
285a6bda	110	g = new Dygraph(
078d1d29	111	document.getElementById("graphdiv"), // containing div
285a6bda DV	112	"Date,Temperature\n" + // CSV or path to a CSV file.
	113	"20080507,75\n" +
	114	"20080508,70\n" +
	115	"20080509,80\n",
078d1d29 DV	116	);
	117	</script>
	118	</body>
	119	</html>
	120	</pre>
	121	</td><td valign=top>
285a6bda	122	<div id="graphdiv"></div>
078d1d29	123	<script type="text/javascript">
285a6bda DV	124	g = new Dygraph(
	125	document.getElementById("graphdiv"), // containing div
	126	"Date,Temperature\n" + // CSV or path to a CSV file.
	127	"20080507,75\n" +
	128	"20080508,70\n" +
	129	"20080509,80\n"
	130	);
078d1d29 DV	131	</script>
	132	</td></tr></table>
	133
285a6bda	134	<p>In order to keep this example self-contained, the second parameter is a function that returns CSV data. These lines <i>must</i> begin with a date in the form <i>YYYYMMDD</i>. In most applications, it makes more sense to include a CSV file instead. If the second parameter to the constructor is a string, it will be interpreted as the path to a CSV file. The Dygraph will perform an XMLHttpRequest to retrieve this file and display the data when it becomes available. Make sure your CSV file is readable and serving from a place that understands XMLHttpRequest's! In particular, you cannot specify a CSV file using <code>"file:///"</code>. Here's an example: (data from <a href="http://www.wunderground.com/history/airport/KNUQ/2007/1/1/CustomHistory.html?dayend=31&monthend=12&yearend=2007&req_city=NA&req_state=NA&req_statename=NA">Weather Underground</a>)</p>
078d1d29 DV	135
	136	<table>
	137	<tr><th>HTML</th>
	138	<td rowspan=2><img src=arrow.gif /></td>
	139	<th>Output</th></tr>
	140	<tr>
	141	<td valign=top><pre>
	142	<html>
	143	<head>
	144	<script type="text/javascript" src="combined.js"></script>
	145	</head>
	146	<body>
	147	<div id="graphdiv" style="width:600px; height:300px;"></div>
	148	<script type="text/javascript">
285a6bda	149	g = new Dygraph(
078d1d29 DV	150	document.getElementById("graphdiv"),
078d1d29 DV	151	"temperatures.csv", // path to CSV file
285a6bda	152	{} // additional options
078d1d29 DV	153	);
	154	</script>
	155	</body>
	156	</html>
	157	</pre>
	158	</td><td valign=top>
	159	<div id="graphdiv2" style="width:600px; height:300px;"></div>
	160	<script type="text/javascript">
285a6bda	161	g2 = new Dygraph(
078d1d29	162	document.getElementById("graphdiv2"),
285a6bda	163	"temperatures.csv", {}
078d1d29 DV	164	);
	165	</script>
	166	</td></tr></table>
	167
	168	<p>Click <a href="temperatures.csv">here</a> to view the <code>temperatures.csv</code> file. There are a few things to note here:</p>
	169
	170	<ul>
285a6bda DV	171	<li>The Dygraph sent off an XHR to get the temperatures.csv file.</li>
	172	<li>The labels were taken from the first line of <code>temperatures.csv</code>, which is <code>Date,High,Low</code>.</li>
	173	<li>The Dygraph automatically chose two different, easily-distinguishable colors for the two data series.</li>
078d1d29	174	<li>The labels on the x-axis have switched from days to months. If you zoom in, they'll switch to weeks and then days.</li>
285a6bda	175	<li>Some heuristics are used to determine a good vertical range for the data. The idea is to make all the data visible and have human-friendly values on the axis (i.e. 200 instead of 193.4). Generally this works well.</li>
078d1d29 DV	176	<li>The data is very spiky. A moving average would be easier to interpret.</li>
	177	</ul>
	178
285a6bda	179	<p>This problem can be fixed by specifying the appropriate options in the "additional options" parameter to the Dygraph constructor. To set the number of days for a moving average, use the <b>rollPeriod</b> option. Here's how it's done:</p>
078d1d29 DV	180
	181	<table>
	182	<tr><th>HTML</th>
	183	<td rowspan=2><img src=arrow.gif /></td>
	184	<th>Output</th></tr>
	185	<tr>
	186	<td valign=top><pre>
	187	<html>
	188	<head>
	189	<script type="text/javascript" src="combined.js"></script>
	190	</head>
	191	<body>
	192	<div id="graphdiv" style="width:600px; height:300px;"></div>
	193	<script type="text/javascript">
285a6bda	194	g = new Dygraph(
078d1d29	195	document.getElementById("graphdiv"),
285a6bda	196	"temperatures.csv",
078d1d29	197	{ rollPeriod: 7,
738fc797	198	showRoller: true,
078d1d29 DV	199	}
	200	);
	201	</script>
	202	</body>
	203	</html>
	204	</pre>
	205	</td><td valign=top>
	206	<div id="graphdiv3" style="width:600px; height:300px;"></div>
	207	<script type="text/javascript">
285a6bda	208	g3 = new Dygraph(
078d1d29	209	document.getElementById("graphdiv3"),
285a6bda	210	"temperatures.csv",
078d1d29	211	{ rollPeriod: 7,
738fc797	212	showRoller: true,
078d1d29 DV	213	}
	214	);
	215	</script>
	216	</td></tr></table>
	217
738fc797	218	<p>A rolling average can be set using the text box in the lower left-hand corner of the graph (the showRoller attribute is what makes this appear).</p>
078d1d29 DV	219
078d1d29 DV	220	<h2>Error Bars</h2>
285a6bda	221	<p>Another significant feature of the dygraphs library is the ability to display error bars around data series. One standard deviation must be specified for each data point. A +/-<i>n</i> sigma band will be drawn around the data series at that point. If a moving average is being displayed, dygraphs will compute the standard deviation of the average at each point. (i.e. <i>σ</i> = sqrt((<i>σ_1</i>^2 + <i>σ_2</i>^2 + ... + <i>σ_n</i>^2)/<i>n</i>))</p>
078d1d29 DV	222
	223	<p>Here's a demonstration. There are two data series. One is <code>N(100,10)</code> with a standard deviation of 10 specified at each point. The other is <code>N(80,20)</code> with a standard deviation of 20 specified at each point. The CSV file was generated using Octave and can be viewed <a href="twonormals.csv">here</a>.</p>
	224
	225	<table>
	226	<tr><th>HTML</th>
	227	<td rowspan=2><img src=arrow.gif /></td>
	228	<th>Output</th></tr>
	229	<tr>
	230	<td valign=top><pre>
	231	<html>
	232	<head>
	233	<script type="text/javascript"
	234	src="combined.js"></script>
	235	</head>
	236	<body>
	237	<div id="graphdiv"
	238	style="width:800px; height:400px;"
	239	></div>
	240	<script type="text/javascript">
	241	$ = document.getElementById;
285a6bda	242	g = new Dygraph(
078d1d29 DV	243	$("graphdiv"),
078d1d29 DV	244	"twonormals.csv",
078d1d29	245	{ rollPeriod: 7,
738fc797	246	showRoller: true,
078d1d29 DV	247	errorBars: true,
	248	valueRange: [50,125]
	249	}
	250	);
	251	</script>
	252	</body>
	253	</html>
	254	</pre>
	255	</td><td valign=top>
	256	<div id="graphdiv4" style="width:800px; height:400px;"></div>
	257	<script type="text/javascript">
	258	$ = document.getElementById;
285a6bda	259	new Dygraph(
078d1d29 DV	260	document.getElementById("graphdiv4"),
078d1d29 DV	261	"twonormals.csv",
078d1d29	262	{ rollPeriod: 14,
738fc797	263	showRoller: true,
078d1d29 DV	264	errorBars: true,
	265	valueRange: [50, 125]
	266	}
	267	);
	268	</script>
	269	</td></tr></table>
	270
	271	<p>Things to note here:</p>
	272	<ul>
	273	<li>The <b>errorBars</b> option affects both the interpretation of the CSV file and the display of the graph. When <b>errorBars</b> is set to true, each line is interpreted as <i>YYYYMMDD</i>,<i>A</i>,<i>sigma_A</i>,<i>B</i>,<i>sigma_B</i>,...</li>
	274	<li>The first line of the CSV file doesn't mention the error columns. In this case, it's just "Date,Series1,Series2".</li>
	275	<li>The averaging visibly affects the error bars. This is most clear if you crank up the rolling period to something like 100 days. For the earliest dates, there won't be 100 data points to average so the signal will be noisier. The error bars get smaller like sqrt(N) going forward in time until there's a full 100 points to average.</li>
	276	<li>The error bars are partially transparent. This can be seen when they overlap one another.</li>
	277	</ul>
	278
353a0294 DV	279	<h2>One last demo</h2>
	280
	281	<p>This chart shows monthly closes of the Dow Jones Industrial Average, both in nominal and real (i.e. adjusted for inflation) dollars. The shaded areas show its monthly high and low. CPI values with a base from 1982-84 are used to adjust for inflation.</p>
	282
	283	<div id=dow_chart style="width:1000px; height:400px;"></div>
	284	<script type="text/javascript">
	285	// From http://www.econstats.com/eqty/eq_d_mi_3.csv
285a6bda	286	dow = new Dygraph(
353a0294 DV	287	document.getElementById('dow_chart'),
353a0294 DV	288	"dow.txt",
353a0294	289	{
738fc797	290	showRoller: true,
353a0294 DV	291	customBars: true,
	292	labelsKMB: true,
	293	padding: {left:30, right:30, top:5, bottom:5}
	294	});
	295	</script>
	296
	297
078d1d29	298	<h2>Other Options</h2>
285a6bda	299	<p>These are the options that can be passed in through the optional third parameter of the Dygraph constructor.</p>
078d1d29 DV	300
	301	<table class=thinborder width=1000>
	302	<tr><th>Name</th><th>Sample Value</th><th>Description</th></tr>
	303	<tr>
	304	<td><b>rollPeriod</b></td>
	305	<td><code>7</code></td>
	306	<td>Number of days over which to average data. Discussed extensively above.</td>
	307	</tr><tr>
738fc797 DV	308	<td><b>showRoller</b></td>
	309	<td><code>true</code></td>
	310	<td>Should the rolling average period text box be shown? Default is false.</td>
	311	</tr><tr>
078d1d29 DV	312	<td><b>colors</b></td>
	313	<td><code>['red', '#00FF00']</code></td>
	314	<td>List of colors for the data series. These can be of the form "#AABBCC"
	315	or "rgb(255,100,200)" or "yellow", etc. If not specified, equally-spaced
	316	points around a color wheel are used.</td>
	317	</tr><tr>
	318	<td><b>colorSaturation</b></td>
	319	<td><code>1.0</code></td>
	320	<td>If <b>colors</b> is not specified, saturation of the
	321	automatically-generated data series colors. (0.0-1.0, default:
	322	1.0)</td>
	323	</tr><tr>
	324	<td><b>colorValue</b></td>
	325	<td><code>0.5</code></td>
	326	<td>If colors is not specified, value of the data series colors, as in
	327	hue/saturation/value. (0.0-1.0, default 0.5)</td>
	328	</tr><tr>
	329	<td><b>clickCallback</b></td>
	330	<td><code>function(e,date){ alert(date); }</code></td>
	331	<td>A function to call when a data point is clicked. The function should take
	332	two arguments, the event object for the click and the date that was
	333	clicked. (default null)</td>
	334	</tr><tr>
	335	<td><b>errorBars</b></td>
	336	<td><code>false</code></td>
	337	<td>Does the data contain standard deviations? Setting this to true alters
	338	the input format (see above). (default false)</td>
	339	</tr><tr>
	340	<td><b>strokeWidth</b></td>
	341	<td><code>2.0</code></td>
	342	<td>Width of the data lines. This can be used to increase the contrast or
	343	some graphs. (default 1.0)</td>
	344	</tr><tr>
	345	<td><b>dateWindow</b></td>
	346	<td><code>[(new Date('2006-01-01')).valueOf(),<br/>
	347	(new Date()).valueOf()]</code></td>
	348	<td>Initially zoom in on a section of the graph. Is of the form [earliest,
	349	latest], where earliest/latest are millis since epoch. By default, the
	350	full range of the input is shown.</td>
	351	</tr><tr>
	352	<td><b>valueRange</b></td>
	353	<td><code>[10, 110]</code></td>
	354	<td>Explicitly set the vertical range of the graph to [low, high]. By
	355	default, some clever heuristics are used (see above).</td>
	356	</tr><tr>
	357	<td><b>minTickSize</b></td>
	358	<td><code>1</code</td>
	359	<td>The difference between ticks on the y-axis can be greater than or equal
	360	to this, but no less. If you set it to 1, for instance, you'll never get
	361	nonintegral gaps between ticks.</td>
	362	</tr><tr>
	363	<td><b>labelsSeparateLines</b></td>
	364	<td><code>true</code></td>
	365	<td>Put <br/> between lines in the label string. Often used in
	366	conjunction with <b>labelsDiv</b>. (default false)</td>
	367	</tr><tr>
	368	<td><b>labelsDiv</b></td>
	369	<td><code>document.getElementById('foo')</code></td>
	370	<td>Show data labels in an external div, rather than on the graph. (default
	371	null)</td>
	372	</tr><tr>
	373	<td><b>labelsKMB</b></td>
	374	<td><code>true</code></td>
	375	<td>Show K/M/B for thousands/millions/billions on y-axis (default
376	false).</td>
377	</tr>
378	<tr>
379	<td><b>padding</b></td>
380	<td><code>{left: 40, right: 30,<br/>top: 5,
381	bottom: 15}</code></td>
382	<td>Adds extra pixels of padding around the graph. Sometimes a dygraph
383	gets clipped by surrounding text (see the Demo at the top of this page).
384	Setting this property appropriately will fix this problem.</td>
385	</tr>
386	</table>
387
285a6bda	388	<p>Any options you specify also get passed on to PlotKit's <a href="http://media.liquidx.net/js/plotkit-doc/PlotKit.Renderer.html">Renderer</a> class. dygraphs will override some of these (e.g. strokeColor), but others may be useful. The <code>padding</code> property is an example of this.</p>
078d1d29 DV	389
	390	<h2>Common Gotchas</h2>
	391	<p>Here are a few problems that I've frequently run into while using the
	392	dygraphs library.</p>
	393
	394	<ul>
	395	<li>Make sure your CSV files are readable! If your graph isn't showing up,
	396	the XMLHttpRequest for the CSV file may be failing. You can determine whether
	397	this is the case using tools like <a
	398	href="http://www.getfirebug.com/">Firebug</a>.</li>
	399
	400	<li>Make sure your CSV files are in the correct format. They must be of the
285a6bda DV	401	form <code>YYYYMMDD,series1,series2,...</code>. And if you set the
	402	<code>errorBars</code> property, make sure you alternate data series and
	403	standard deviations.</li>
078d1d29 DV	404
	405	<li>dygraphs are not happy when placed inside a <code><center></code>
	406	tag. This applies to the CSS <code>text-align</code> property as well. If you
285a6bda	407	want to center a Dygraph, put it inside a table with "align=center"
078d1d29 DV	408	set.</li>
078d1d29 DV	409
078d1d29 DV	410	<li>Don't set the <code>dateWindow</code> property to a date. It expects
	411	milliseconds since epoch, which can be obtained from a JavaScript Date
	412	object's valueOf method.</li>
	413	</ul>
	414
	415	<p><font size=-1>Created May 9, 2008 by <a href=mailto:danvdk@gmail.com>Dan Vanderkam</a></font></p>
	416
	417	</body>
	418	</html>