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   3   <head>
   4     <title>dygraphs JavaScript Visualization Library</title>
   5     <!--[if IE]>
   6       <script type="text/javascript" src="excanvas.js"></script>
   7     <![endif]-->
   8     <script type="text/javascript" src="dygraph-combined.js"></script>
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  11   <body>
  12     <div id="nav">
  13       <h2>Documentation</h2>
  14       <ul>
  15         <li><a href="#demo">Demo</a></li>
  16         <li><a href="#usage">Usage</a></li>
  17         <li><a href="#ie">IE Compatibility</a></li>
  18         <li><a href="#gviz">GViz Data</a></li>
  19         <li><a href="#baseball">Baseball chart</a></li>
  20         <li><a href="#stock">Stock chart</a></li>
  21         <li><a href="#options">Options Reference</a></li>
  22         <li><a href="#gwt">GWT Compatibility</a></li>
  23         <li><a href="#policy">Data Policy</a></li>
  24       </ul>
  25
  26       <h2>Features</h2>
  27       <ul>
  28         <li><a href="data.html">Data Formats</a></li>
  29         <li><a href="annotations.html">Annotations</a></li>
  30       </ul>
  31
  32       <h2>Project</h2>
  33       <ul>
  34         <li><a href="http://github.com/danvk/dygraphs">Source</a></li>
  35         <li><a href="http://code.google.com/p/dygraphs/issues/">Issues</a></li>
  36         <li><a href="http://code.google.com/p/dygraphs/issues/entry">Report Bug</a></li>
  37         <li><a href="mailto:dygraphs-users [at] googlegroups.com">Contact</a></li>
  38       </ul>
  39
  40       <h2>Gallery</h2>
  41       <ul>
  42         <li><a href="tests/">(browse demos)</a></li>
  43         <li><a href="tests/demo.html">Basic Demo</a></li>
  44         <li><a href="tests/gviz.html">GViz Demo</a></li>
  45         <li><a href="tests/plotter.html">Equation Plotter</a></li>
  46         <li><a href="tests/perf.html">Performance Test</a></li>
  47         <li><a href="tests/annotation.html">Annotations</a></li>
  48         <li><a href="tests/annotation-gviz.html">Annotations (GViz)</a></li>
  49         <li><a href="tests/fillGraph.html">Filled Chart</a></li>
  50         <li><a href="tests/perf.html">Fractions</a></li>
  51         <li><a href="tests/visibility.html">Visibility</a></li>
  52         <li><a href="tests/label-div.html">Labels in a DIV</a></li>
  53         <li><a href="tests/numeric-axis.html">Numeric Axis</a></li>
  54         <li><a href="tests/draw-points.html">Dotted Points</a></li>
  55         <li><a href="tests/native-format.html">Native Format</a></li>
  56         <li><a href="tests/grid_dot.html">Crazy Styles</a></li>
  57         <li><a href="tests/spacing.html">Tick spacing</a></li>
  58         <li><a href="tests/callback.html">Callbacks</a></li>
  59         <li><a href="tests/crosshair.html">Crosshairs</a></li>
  60         <li><a href="tests/hourly.html">Hourly/Minutely data</a></li>
  61         <li><a href="tests/isolated-points.html">Isolated Points</a></li>
  62         <li><a href="tests/missing-data.html">Missing Data</a></li>
  63         <li><a href="tests/border.html">Bordered chart</a></li>
  64         <li><a href="tests/custom-bars.html">Custom Bars</a></li>
  65         <li><a href="tests/customLabel.html">Custom Label Styles</a></li>
  66         <li><a href="tests/dygraph.html">Minimal Example</a></li>
  67         <li><a href="tests/negative.html">Negative Numbers</a></li>
  68         <li><a href="tests/noise.html">Noisy Data</a></li>
  69         <li><a href="tests/two-series.html">Multiple Series</a></li>
  70         <li><a href="tests/highlighted-region.html">Custom Underlay / background</a></li>
  71         <li><a href="tests/zoom.html">Tests for zoom operations</a></li>
  72       </ul>
  73     </div>
  74
  75     <div id="content">
  76       <h1>dygraphs JavaScript Visualization Library</h1>
  77
  78       <p><a href="http://github.com/danvk/dygraphs">http://github.com/danvk/dygraphs</a></p>
  79       <p>See <a href="http://groups.google.com/group/dygraphs-users">mailing list</a>, <a href="http://github.com/danvk/dygraphs/downloads/">downloads</a>, <a href="tests/">gallery</a> and <a href="http://code.google.com/p/dygraphs/issues/">open issues</a></p>
  80
  81       <p>dygraphs is an open source JavaScript library that produces produces interactive, zoomable charts of time series. It is designed to display dense data sets and enable users to explore and interpret them.</p>
  82
  83       <h3 id="demo">A demo is worth a thousand words:</h3>
  84
  85       <p style="font-size:0.8em">(Mouse over to highlight individual values. Click and drag to zoom. Double-click to zoom back out. Change the number and hit enter to adjust the averaging period.)</p>
  86
  87       <div id="title" style="width:800px; margin: 1em;text-align:center; font-weight: bold; font-size: 125%;">Temperatures in New York vs. San Francisco</div>
  88
  89       <div id="demodiv" style="width:800px; height:320px;"></div>
  90       <script type="text/javascript">
  91         g = new Dygraph(
  92           document.getElementById("demodiv"),
  93           "ny-vs-sf.txt",
  94           {
  95             rollPeriod: 14,
  96             showRoller: true,
  97             customBars: true,
  98             yAxisLabelWidth: 30
  99           }
 100         );
 101       </script>
 102
 103       <h4>Some things to notice:</h4>
 104       <ul>
 105         <li>There's less seasonal temperature variation in SF than in NY.</li>
 106         <li>The difference is about 15&deg; F for SF vs. 50&deg; F for NY.</li>
 107         <li>The daily data (set rolling period to 1) is quite noisy and hides this conclusion.</li>
 108         <li>Using a 14-day moving average makes it clearer. A 100-day rolling period averages out nearly all the specifics from the data.</li>
 109         <li>There's a gap in the data for SF, when the weather station was down (zoom into October 2007 to see it).</li>
 110         <li>The bands around each point indicate average highs and lows.</li>
 111         <li>There is a <em>lot</em> of data in this chart: low, average and high for each city on each day of a three year period &asymp; 6000 data points in all.</li>
 112       </ul>
 113
 114       <p>dygraphs allows the user to explore the data and discover these facts.</p>
 115
 116       <p>For more demos, browse the dygraph <a href="tests/">tests</a> directory.</p>
 117
 118       <h3>Features</h3>
 119       <p>Some of the features of dygraphs:</p>
 120       <ul>
 121         <li>Plots time series without using an external server or Flash</li>
 122         <li>Works in Internet Explorer (using excanvas)</li>
 123         <li>Lightweight (57kb) and responsive</li>
 124         <li>Displays values on mouseover (this makes it easily discoverable)</li>
 125         <li>Supports error bands around data series</li>
 126         <li>Interactive zoom</li>
 127         <li>Displays Annotations on the chart</li>
 128         <li>Adjustable averaging period</li>
 129         <li>Can intelligently chart fractions</li>
 130         <li>Customizable click-through actions</li>
 131         <li>Compatible with the Google Visualization API</li>
 132         <li>Intelligent defaults make it easy to use</li>
 133       </ul>
 134
 135       <h2 id="usage">Usage</h2>
 136
 137       <p>To use dygraphs, include the <code><a href="http://github.com/danvk/dygraphs/downloads/">dygraph-combined.js</a></code> JavaScript file and instantiate a <code>Dygraph</code> object.</p>
 138
 139       <p>Here's a basic example to get things started:</p>
 140
 141       <div class="example" style="clear:both;">
 142         <div class="codeblock" style="float:left;width:400px;">
 143           <h3 style="text-align:center">HTML</h3>
 144           <code>
 145   <pre>
 146 &lt;html&gt;
 147 &lt;head&gt;
 148 &lt;script type=&quot;text/javascript&quot;
 149   src=&quot;dygraph-combined.js&quot;&gt;&lt;/script&gt;
 150 &lt;/head&gt;
 151 &lt;body&gt;
 152 &lt;div id=&quot;graphdiv&quot;&gt;&lt;/div&gt;
 153 &lt;script type=&quot;text/javascript&quot;&gt;
 154   g = new Dygraph(
 155
 156     // containing div
 157     document.getElementById(&quot;graphdiv&quot;),
 158
 159     // CSV or path to a CSV file.
 160     &quot;Date,Temperature\n&quot; +
 161     &quot;2008-05-07,75\n&quot; +
 162     &quot;2008-05-08,70\n&quot; +
 163     &quot;2008-05-09,80\n&quot;
 164
 165   );
 166 &lt;/script&gt;
 167 &lt;/body&gt;
 168 &lt;/html&gt;
 169 </pre>
 170           </code>
 171         </div>
 172         <div class="codeoutput" style="float:left;">
 173           <h3 style="text-align:center">OUTPUT</h3>
 174           <div id="graphdiv"></div>
 175           <script type="text/javascript">
 176             g = new Dygraph(
 177
 178               // containing div
 179               document.getElementById("graphdiv"),
 180
 181               // CSV or path to a CSV file.
 182               "Date,Temperature\n" +
 183               "2008-05-07,75\n" +
 184               "2008-05-08,70\n" +
 185               "2008-05-09,80\n"
 186             );
 187           </script>
 188         </div>
 189       </div>
 190
 191       <p style="clear:both">In order to keep this example self-contained, the second parameter is raw CSV data. The dygraphs library parses this data (including column headers), resizes its container to a reasonable default, calculates appropriate axis ranges and tick marks and draws the graph.</p>
 192
 193       <p>In most applications, it makes more sense to include a CSV file instead. If the second parameter to the constructor doesn't contain a newline, 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&amp;monthend=12&amp;yearend=2007&amp;req_city=NA&amp;req_state=NA&amp;req_statename=NA">Weather Underground</a>)</p>
 194
 195       <div class="example" style="clear:both;">
 196         <div class="codeblock" style="float:left;width:400px;">
 197           <h3 style="text-align:center">HTML</h3>
 198           <code>
 199 <pre>
 200 &lt;html&gt;
 201 &lt;head&gt;
 202 &lt;script type=&quot;text/javascript&quot;
 203   src=&quot;dygraph-combined.js&quot;&gt;&lt;/script&gt;
 204 &lt;/head&gt;
 205 &lt;body&gt;
 206 &lt;div id=&quot;graphdiv2&quot;
 207   style=&quot;width:500px; height:300px;&quot;&gt;&lt;/div&gt;
 208 &lt;script type=&quot;text/javascript&quot;&gt;
 209   g2 = new Dygraph(
 210     document.getElementById(&quot;graphdiv2&quot;),
 211     &quot;temperatures.csv&quot;, // path to CSV file
 212     {}          // options
 213   );
 214 &lt;/script&gt;
 215 &lt;/body&gt;
 216 &lt;/html&gt;
 217 </pre>
 218           </code>
 219         </div>
 220         <div class="codeoutput" style="float:left;">
 221           <h3 style="text-align:center">OUTPUT</h3>
 222           <div id="graphdiv2" style="width:500px; height:300px;"></div>
 223           <script type="text/javascript">
 224             g2 = new Dygraph(
 225               document.getElementById("graphdiv2"),
 226               "temperatures.csv",
 227               {}
 228             );
 229           </script>
 230         </div>
 231       </div>
 232
 233       <p style="clear:both;">The file used is <code><a href="temperatures.csv">temperatures.csv</a></code>.</p>
 234
 235       <p>There are a few things to note here:</p>
 236
 237       <ul>
 238         <li>The Dygraph sent off an XHR to get the temperatures.csv file.</li>
 239         <li>The labels were taken from the first line of <code>temperatures.csv</code>, which is <code>Date,High,Low</code>.</li>
 240         <li>The Dygraph automatically chose two different, easily-distinguishable colors for the two data series.</li>
 241         <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>
 242         <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>
 243         <li>The data is very spiky. A moving average would be easier to interpret.</li>
 244       </ul>
 245
 246       <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 <code>rollPeriod</code> option. Here's how it's done:</p>
 247
 248       <div class="example" style="clear:both;">
 249         <div class="codeblock" style="float:left;width:400px;">
 250           <h3 style="text-align:center">HTML</h3>
 251           <code>
 252 <pre>
 253 &lt;html&gt;
 254 &lt;head&gt;
 255 &lt;script type=&quot;text/javascript&quot;
 256   src=&quot;dygraph-combined.js&quot;&gt;&lt;/script&gt;
 257 &lt;/head&gt;
 258 &lt;body&gt;
 259 &lt;div id=&quot;graphdiv3&quot;
 260   style=&quot;width:500px; height:300px;&quot;&gt;&lt;/div&gt;
 261 &lt;script type=&quot;text/javascript&quot;&gt;
 262   g3 = new Dygraph(
 263     document.getElementById(&quot;graphdiv3&quot;),
 264     &quot;temperatures.csv&quot;,
 265     {
 266       rollPeriod: 7,
 267       showRoller: true
 268     }
 269   );
 270 &lt;/script&gt;
 271 &lt;/body&gt;
 272 &lt;/html&gt;
 273 </pre>
 274           </code>
 275         </div>
 276         <div class="codeoutput" style="float:left;">
 277           <h3 style="text-align:center">OUTPUT</h3>
 278           <div id="graphdiv3" style="width:500px; height:300px;"></div>
 279           <script type="text/javascript">
 280             g3 = new Dygraph(
 281               document.getElementById("graphdiv3"),
 282               "temperatures.csv",
 283               {
 284                 rollPeriod: 7,
 285                 showRoller: true
 286               }
 287             );
 288           </script>
 289         </div>
 290       </div>
 291
 292       <p style="clear:both;">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). Also note that we've explicitly set the size of the chart div.</p>
 293
 294       <h2>Error Bars</h2>
 295
 296       <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 <em>&plusmn;n</em> 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. <em>&sigma; = sqrt( (&sigma;<sub>1<sup>2</sup></sub> + &sigma;<sub>2<sup>2</sup></sub> + ... + &sigma;<sub>n<sup>2</sup></sub>) / n )</em></p>
 297
 298       <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 at <a href="twonormals.csv">twonormals.csv</a>.</p>
 299
 300       <div class="example" style="clear:both;">
 301         <div class="codeblock" style="float:left;width:400px;">
 302           <h3 style="text-align:center">HTML</h3>
 303           <code>
 304 <pre>
 305 &lt;html&gt;
 306 &lt;head&gt;
 307 &lt;script type=&quot;text/javascript&quot;
 308   src=&quot;combined.js&quot;&gt;&lt;/script&gt;
 309 &lt;/head&gt;
 310 &lt;body&gt;
 311 &lt;div id=&quot;graphdiv4&quot;
 312   style=&quot;width:600px; height:300px;&quot;&gt;&lt;/div&gt;
 313 &lt;script type=&quot;text/javascript&quot;&gt;
 314   g4 = new Dygraph(
 315     document.getElementById(&quot;graphdiv4&quot;),
 316     &quot;twonormals.csv&quot;,
 317     {
 318       rollPeriod: 7,
 319       showRoller: true,
 320       errorBars: true,
 321       valueRange: [50,125]
 322     }
 323   );
 324 &lt;/script&gt;
 325 &lt;/body&gt;
 326 &lt;/html&gt;
 327 </pre>
 328           </code>
 329         </div>
 330         <div class="codeoutput" style="float:left;">
 331           <h3 style="text-align:center">OUTPUT</h3>
 332           <div id="graphdiv4" style="width:600px; height:300px;"></div>
 333           <script type="text/javascript">
 334             g4 = new Dygraph(
 335               document.getElementById("graphdiv4"),
 336               "twonormals.csv",
 337               {
 338                 rollPeriod: 7,
 339                 showRoller: true,
 340                 errorBars: true,
 341                 valueRange: [50,125]
 342               }
 343             );
 344           </script>
 345         </div>
 346       </div>
 347
 348       <p style="clear:both;">Things to note here:</p>
 349
 350       <ul>
 351         <li>The <strong>errorBars</strong> option affects both the interpretation of the CSV file and the display of the graph. When <strong>errorBars</strong> is set to true, each line is interpreted as <em>YYYYMMDD</em>, <em>A</em>, <em>sigma_A</em>, <em>B</em>, <em>sigma_B</em>, &hellip;</li>
 352         <li>The first line of the CSV file doesn't mention the error columns. In this case, it's just "Date,Series1,Series2".</li>
 353         <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>
 354         <li>The error bars are partially transparent. This can be seen when they overlap one another.</li>
 355       </ul>
 356
 357       <h2 id="ie">Internet Explorer Compatibility</h2>
 358
 359       <p>The dygraphs library relies heavily on HTML's <code>&lt;canvas&gt;</code> tag, which Microsoft Internet Explorer does not support. Fortunately, some clever engineers created the <a href="http://code.google.com/p/explorercanvas/">excanvas</a> library, which implements the <code>&lt;canvas&gt;</code> tag in IE using VML.</p>
 360
 361       <p>You can add IE support to any page using dygraphs by including the following in your page:</p>
 362
 363 <pre>
 364 &lt;head&gt;
 365   &lt;!--[if IE]&gt;&lt;script src="excanvas.js"&gt;&lt;/script&gt;&lt;![endif]--&gt;
 366 &lt;/head&gt;
 367 </pre>
 368
 369     <p>This works quite well in practice. Charts are responsive, even under VML emulation.</p>
 370
 371     <p>One common gotcha to look out for: make sure you don't have any trailing commas in parameter lists, e.g.</p>
 372
 373 <pre>
 374 new Dygraph(el, data, {
 375   showRoller: true,  // note trailing comma
 376 })</pre>
 377
 378     <p>Most browsers will ignore the trailing comma, but it will break under IE.</p>
 379
 380     <h2 id="gviz">GViz Data</h2>
 381
 382     <p>The <a
 383       href="http://code.google.com/apis/visualization/documentation/index.html">Google
 384       Visualization API</a> provides a standard interface for describing data.
 385     Once you've specified your data using this API, you can plug in any
 386     GViz-compatible visualization. dygraphs is such a visualization. In
 387     particular, it can be used as a drop-in replacement for the
 388     AnnotatedTimeline visualization used on Google Finance and other sites. To
 389     see how this works, check out the <a href="tests/annotation-gviz.html">gviz
 390       annotation demo.</a></p>
 391
 392     <p>For a simple demonstration of how to use dygraphs a GViz visualization, see <a href="http://danvk.org/dygraphs/tests/gviz.html">http://danvk.org/dygraphs/tests/gviz.html</a>. dygraphs can also be used as a GViz gadget. This allows it to be embedded inside of a Google Spreadsheet. For a demonstration of this, see <a   href="http://spreadsheets.google.com/ccc?key=0Anx1yCqeL8YUdDR1c3pPREhraGhkWmdhaURjOXRncXc&amp;hl=en">this spreadsheet</a>. The URL for the gadget is <code><a href="http://danvk.org/dygraphs/gadget.xml">http://danvk.org/dygraphs/gadget.xml</a></code>.</p>
 393
 394     <p>Here's an example of a published gviz gadget using dygraphs:</p>
 395
 396     <script src="http://spreadsheets.google.com/gpub?url=http%3A%2F%2Fkb8jbn8l90ocl9n4b14jrcvp61ceqis5.spreadsheets.gmodules.com%2Fgadgets%2Fifr%3Fup__table_query_url%3Dhttp%253A%252F%252Fspreadsheets.google.com%252Ftq%253Frange%253DA1%25253AC31%2526headers%253D-1%2526key%253D0Anx1yCqeL8YUdDR1c3pPREhraGhkWmdhaURjOXRncXc%2526gid%253D0%2526pub%253D1%26up__table_query_refresh_interval%3D300%26url%3Dhttp%253A%252F%252Fdanvk.org%252Fdygraphs%252Fgadget.xml%253Fnocache&height=215&width=530"></script>
 397
 398     <h2 id="baseball">Charting Fractions</h2>
 399
 400     <p>Situations often arise where you want to plot fractions, e.g. the fraction of respondents in a poll who said they'd vote for candidate X or the number of hits divided by at bats (baseball's batting average). Fractions require special treatment for two main reasons:</p>
 401
 402     <ul>
 403       <li>The average of <code>a1/b1</code> and <code>a2/b2</code> is <code>(a1+a2)/(b1+b2)</code>, not <code>(a1/b1 + a2/b2)/2</code>.</li>
 404       <li>The normal approximation is not always applicable and more sophisticated confidence intervals (e.g. the <a href="http://en.wikipedia.org/wiki/Binomial_proportion_confidence_interval">Wilson confidence interval</a>) must be employed to avoid ratios that exceed 100% or go below 0%.</li>
 405     </ul>
 406
 407     <p>Fortunately, dygraphs handles both of these for you! Here's a chart and the command that generated it:</p>
 408
 409     <div style="width:750px; text-align:center; font-weight: bold; font-size: 125%;">Batting Average for Ichiro Suzuki vs. Mariners (2004)</div>
 410     <div id="baseballdiv" style="width:750px; height:300px;"></div>
 411     <script type="text/javascript">
 412       new Dygraph(
 413         document.getElementById("baseballdiv"),
 414         "suzuki-mariners.txt",
 415         {
 416           fractions: true,
 417           errorBars: true,
 418           showRoller: true,
 419           rollPeriod: 15
 420         }
 421       );
 422     </script>
 423
 424     <p>Command:</p>
 425 <pre>
 426   new Dygraph(
 427     document.getElementById(&quot;baseballdiv&quot;),
 428     &quot;suzuki-mariners.txt&quot;,
 429     {
 430       fractions: true,
 431       errorBars: true,
 432       showRoller: true,
 433       rollPeriod: 15
 434     }
 435   );
 436 </pre>
 437
 438     <p>The <code>fractions</code> option indicates that the values in each column should be parsed as fractions (e.g. "1/2" instead of "0.5"). The <code>errorBars</code> option indicates that we'd like to see a confidence interval around each data point. By default, when <code>fractions</code> is set, you get a Wilson confidence interval. If you look carefully at the chart, you can see that the error bars are asymmetric.</p>
 439
 440     <p>A couple things to notice about this chart:</p>
 441
 442     <ul>
 443       <li>The error bars for Ichiro's batting average are larger than for the Mariners', since he has far fewer at bats than his team.</li>
 444       <li>dygraphs makes it easy to see "batting average over the last 30 games". This is ordinarily quite difficult to compute. It makes it clear where the "hot" and "cold" part of Suzuki's season were.</li>
 445       <li>If you set the averaging period to something large, like 200, you'll see the team's and player's batting average through that game. The final number is the overall batting average for the season.</li>
 446       <li>Where the error bars do not overlap, we can say with 95% confidence that the series differ. There is a better than 95% chance that Ichiro was a better hitter than his team as a whole in 2004, the year he won the batting title.</li>
 447     </ul>
 448
 449     <h2 id="stock">One last demo</h2>
 450
 451     <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>
 452
 453     <div id="dow_chart" style="width:900px; height:350px;"></div>
 454     <p><b>Display: </b>
 455     <input type=checkbox id=0 onClick="stockchange(this)" checked>
 456     <label for="0"> Nominal</label>
 457     <input type=checkbox id=1 onClick="stockchange(this)" checked>
 458     <label for="1"> Real</label>
 459     <input type=checkbox id=ann onClick="annotationschange(this)" checked>
 460     <label for="ann"> Annotations</label>
 461     </p>
 462
 463     <script type="text/javascript">
 464       var stock_annotations = [
 465         {
 466           series: "Real",
 467           x: "1929-08-15",
 468           shortText: "A",
 469           text: "1929 Stock Market Peak"
 470         },
 471         {
 472           series: "Nominal",
 473           x: "1987-08-15",
 474           shortText: "B",
 475           text: "1987 Crash"
 476         },
 477         {
 478           series: "Nominal",
 479           x: "1999-12-15",
 480           shortText: "C",
 481           text: "1999 (.com) Peak"
 482         },
 483         {
 484           series: "Nominal",
 485           x: "2007-10-15",
 486           shortText: "D",
 487           text: "All-Time Market Peak"
 488         }
 489       ];
 490
 491     // From http://www.econstats.com/eqty/eq_d_mi_3.csv
 492       stockchart = new Dygraph(
 493         document.getElementById('dow_chart'),
 494         "dow.txt",
 495         {
 496           showRoller: true,
 497           customBars: true,
 498           labelsKMB: true,
 499           drawCallback: function(g, is_initial) {
 500             if (!is_initial) return;
 501             g.setAnnotations( stock_annotations );
 502           }
 503         }
 504       );
 505
 506       function stockchange(el) {
 507         stockchart.setVisibility(el.id, el.checked);
 508       }
 509
 510       function annotationschange(el) {
 511         if (el.checked) {
 512           stockchart.setAnnotations(stock_annotations);
 513         } else {
 514           stockchart.setAnnotations([]);
 515         }
 516       }
 517     </script>
 518 <!--
 519
 520 Here is a script to regenerate the Dow Jones plot:
 521
 522 # Get unadjusted DJIA data in a nice format:
 523 curl -O http://www.econstats.com/eqty/eq_d_mi_3.csv
 524 sed '1,17d' eq_d_mi_3.csv | cut -d, -f1,6 | perl -pe 's/(\d{4}-\d\d)-\d\d/$1/g' | perl -pe 's/, */\t/' | grep -v 'na' | perl -ne 'chomp; ($m,$v) = split/\t/; $close{$m} = $v; if ($low{$m} == 0 || $v < $low{$m}) { $low{$m}=$v } if ($v > $high{$m}) { $high{$m} = $v } END { for $x(sort keys %close) { print "$x\t$low{$x}\t$close{$x}\t$high{$x}\n" } } ' > monthly-djia.tsv
 525
 526 # Fetch and format the CPI data:
 527 curl 'http://data.bls.gov/PDQ/servlet/SurveyOutputServlet?series_id=CUUR0000SA0&years_option=all_years&periods_option=all_periods&output_type=column&output_format=text&delimiter=comma' > cpi-u.txt
 528 sed '1,/Series Id,Year,/d' cpi-u.txt | sed '/^$/,$d' | cut -d, -f2,3,4 | perl -ne 'print if /,M(0[0-9]|1[012]),/' | perl -pe 's/(\d{4}),M(\d{2}),/$1-$2\t/g' > cpi-u.tsv
 529
 530 # Merge:
 531 join -t'     ' cpi-u.tsv monthly-djia.tsv > annotated-djia.tsv
 532 perl -ne 'BEGIN{print "Month,Nominal,Real\n"} chomp; ($m,$cpi,$low,$close,$high) = split /\t/; $cpi /= 100.0; print "$m-15,$low;$close;$high,",($low/$cpi),";",($close/$cpi),";",($high/$cpi),"\n"' annotated-djia.tsv > dow.txt
 533
 534 -->
 535
 536     <h2 id="options">Other Options</h2>
 537
 538     <p>These are the options that can be passed in through the optional third parameter of the Dygraph constructor. Under each option is a set of links to tests which demonstrate its use. While we attempt to keep this list up-to-date, a more complete list can be found in the <code>Dygraph.DEFAULT_ATTRS</code> map in <code>dygraph.js</code> and the <code>this.options</code> map in <code>dygraph-canvas.js</code>.</p>
 539
 540     <table class="thinborder" width="900">
 541       <thead>
 542         <tr>
 543           <th width="150">Name</th>
 544           <th width="200">Values</th>
 545           <th width="150">Default</th>
 546           <th>Description</th>
 547         </tr>
 548       </thead>
 549       <tbody>
 550         <tr>
 551           <td><strong>includeZero</strong></td>
 552           <td><code>boolean</code></td>
 553           <td><code>false</code></td>
 554         <td>Usually, dygraphs will use the range of the data plus some padding to set the range of the y-axis. If this option is set, the y-axis will always include zero, typically as the lowest value. This can be used to avoid exaggerating the variance in the data.
 555         <div class="tests">Tests: <a href="tests/no-range.html">no-range</a> <a href="tests/numeric-gviz.html">numeric-gviz</a> <a href="tests/small-range-zero.html">small-range-zero</a> </div>
 556           </td>
 557         </tr>
 558         <tr>
 559           <td><strong>rollPeriod</strong></td>
 560           <td><code>integer &gt;= 1</code></td>
 561           <td><code>1</code></td>
 562           <td>Number of days over which to average data. Discussed extensively above.
 563         <div class="tests">Tests: <a href="tests/demo.html">demo</a> <a href="tests/two-series.html">two-series</a> <a href="tests/noise.html">noise</a> </div>
 564         </td>
 565         </tr>
 566         <tr>
 567           <td><strong>showRoller</strong></td>
 568           <td><code>boolean</code></td>
 569           <td><code>false</code></td>
 570           <td>If the rolling average period text box should be shown.
 571           <div class="tests">Tests: <a href="tests/callback.html">callback</a> <a href="tests/crosshair.html">crosshair</a> <a href="tests/fractions.html">fractions</a> <a href="tests/isolated-points.html">isolated-points</a> <a href="tests/numeric-gviz.html">numeric-gviz</a> <a href="tests/underlay-callback.html">underlay-callback</a> <a href="tests/highlighted-region.html">highlighted-region</a></div>
 572           </td>
 573         </tr>
 574         <tr>
 575           <td><strong>colors</strong></td>
 576           <td><code>['red', '#00FF00']</code></td>
 577           <td><code></code></td>
 578           <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.
 579           <div class="tests">Tests: <a href="tests/color-visibility.html">color-visibility</a> <a href="tests/demo.html">demo</a> </div>
 580           </td>
 581         </tr>
 582         <tr>
 583           <td><strong>fillGraph</strong></td>
 584           <td><code>boolean<br/></code></td>
 585           <td><code>false</code></td>
 586           <td>Should the area underneath the graph be filled? This option is not
 587           compatible with error bars.
 588           <div class="tests">Tests: <a href="tests/fillGraph.html">fillGraph</a> </div>
 589           </td>
 590         </tr>
 591         <tr>
 592           <td><strong>visibility</strong></td>
 593           <td><code>Array of booleans<br/></code></td>
 594           <td><code>[true, true, ...]</code></td>
 595           <td>Which series should initially be visible? Once the Dygraph has
 596           been constructed, you can access and modify the visibility of each
 597           series using the <code>visibility</code> and
 598           <code>setVisibility</code> methods.
 599           <div class="tests">Tests: <a href="tests/visibility.html">visibility</a> <a href="tests/color-visibility.html">color-visibility</a> </div>
 600           </td>
 601         </tr>
 602         <tr>
 603           <td><strong>colorSaturation</strong></td>
 604           <td><code>0.0 - 1.0</code></td>
 605           <td><code>1.0</code></td>
 606           <td>If <strong>colors</strong> is not specified, saturation of the automatically-generated data series colors.
 607           <div class="tests">Tests: <font color=red>none</font></div>
 608           </td>
 609         </tr>
 610         <tr>
 611           <td><strong>colorValue</strong></td>
 612           <td><code>float (0.0 &mdash; 1.0)</code></td>
 613           <td><code>1.0</code></td>
 614           <td>If colors is not specified, value of the data series colors, as in hue/saturation/value. (0.0-1.0, default 0.5)
 615           <div class="tests">Tests: <font color=red>none</font></div>
 616           </td>
 617         </tr>
 618         <tr>
 619           <td><strong>clickCallback</strong></td>
 620           <td><code>function(e, date){<br>&nbsp;&nbsp;&nbsp;&nbsp;alert(date);<br>}</code></td>
 621           <td><code>null</code></td>
 622           <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)
 623           <div class="tests">Tests: <a href="tests/callback.html">callback</a> </div>
 624           </td>
 625         </tr>
 626         <tr>
 627           <td><strong>zoomCallback</strong></td>
 628           <td><code>function(minDate,<br/>maxDate,<br/>minValue,<br/>maxValue){}</code></td>
 629           <td><code>null</code></td>
 630           <td>A function to call when the zoom window is changed (either by zooming in or out). minDate and maxDate are milliseconds since epoch. minValue and maxValue are y-axis range values.
 631           <div class="tests">Tests: <a href="tests/callback.html">callback</a> <a href="tests/zoom.html">zoom</a></div>
 632           </td>
 633         </tr>
 634         <tr>
 635           <td><strong>strokeWidth</strong></td>
 636           <td><code>integer</code></td>
 637           <td><code>1</code></td>
 638           <td>Width of the data lines. This can be used to increase the contrast or some graphs.
 639           <div class="tests">Tests: <font color=red>none</font></div>
 640           </td>
 641         </tr>
 642         <tr>
 643           <td><strong>dateWindow</strong></td>
 644           <td><code>[<br>&nbsp;&nbsp;Date.parse('2006-01-01'),<br>&nbsp;&nbsp;(new Date()).valueOf()<br>]</code></td>
 645           <td rowspan="2"><code>Full range of the<br/> input is shown</code></td>
 646           <td>Initially zoom in on a section of the graph. Is of the form [earliest, latest], where earliest/latest are milliseconds since epoch.
 647           <div class="tests">Tests: <a href="tests/dateWindow.html">dateWindow</a> <a href="tests/link-interaction.html">link-interaction</a> </div>
 648           </td>
 649         </tr>
 650         <tr>
 651           <td><strong>valueRange</strong></td>
 652           <td><code>[10, 110]</code></td>
 653           <td>Explicitly set the vertical range of the graph to [low, high].
 654           <div class="tests">Tests: <font color=red>none</font></div>
 655           </td>
 656         </tr>
 657         <tr>
 658           <td><strong>labelsSeparateLines</strong></td>
 659           <td><code>boolean</code></td>
 660           <td><code>false</code></td>
 661           <td>Put <code>&lt;br/&gt;</code> between lines in the label string. Often used in conjunction with <strong>labelsDiv</strong>.
 662           <div class="tests">Tests: <a href="tests/customLabel.html">customLabel</a> <a href="tests/demo.html">demo</a> </div>
 663           </td>
 664         </tr>
 665         <tr>
 666           <td><strong>labelsDiv</strong></td>
 667           <td><code style="font-size: small">document.getElementById('foo')</code><br/>or<br/><code>'foo'</code></td>
 668           <td><code>null</code></td>
 669           <td style="vertical-align:top">Show data labels in an external div, rather than on the graph.  This value can either be a div element or a div id.
 670           <div class="tests">Tests: <a href="tests/label-div.html">label-div</a> </div>
 671           </td>
 672         </tr>
 673         <tr>
 674           <td><strong>labelsShowZeroValues</strong></td>
 675           <td><code>boolean</code></td>
 676           <td><code>true</code></td>
 677           <td>Show zero value labels in the labelsDiv.
 678           <div class="tests">Tests: <a href="tests/label-div.html">label-div</a> </div>
 679           </td>
 680         </tr>
 681         <tr>
 682           <td><strong>labelsKMB</strong></td>
 683           <td><code>true</code></td>
 684           <td><code>false</code></td>
 685           <td>Show K/M/B for thousands/millions/billions on y-axis.
 686           <div class="tests">Tests: <a href="tests/demo.html">demo</a> <a href="tests/labelsKMB.html">labelsKMB</a> <a href="tests/no-range.html">no-range</a> </div>
 687           </td>
 688         </tr>
 689         <tr>
 690           <td><strong>labelsKMG2</strong></td>
 691           <td><code>true</code></td>
 692           <td><code>false</code></td>
 693           <td>Show k/M/G for kilo/Mega/Giga on y-axis. This is different than
 694           <code>labelsKMB</code> in that it uses base 2, not 10.
 695           <div class="tests">Tests: <a href="tests/labelsKMB.html">labelsKMB</a> </div>
 696           </td>
 697         </tr>
 698         <tr>
 699           <td><strong>labelsDivWidth</strong></td>
 700           <td><code>250</code></td>
 701           <td><code></code></td>
 702           <td>Width (in pixels) of the div which shows information on the currently-highlighted points.
 703           <div class="tests">Tests: <a href="tests/customLabel.html">customLabel</a> </div>
 704           </td>
 705         </tr>
 706         <tr>
 707           <td><strong>labelsDivStyles</strong></td>
 708           <td><code>{}</code></td>
 709           <td><code>null</code></td>
 710           <td>Additional styles to apply to the currently-highlighted points div. For example, { 'font-weight': 'bold' } will make the labels bold.
 711           <div class="tests">Tests: <a href="tests/border.html">border</a> <a href="tests/customLabel.html">customLabel</a> </div>
 712           </td>
 713         </tr>
 714         <tr>
 715           <td><strong>highlightCircleSize</strong></td>
 716           <td><code>integer</code></td>
 717           <td><code>3</code></td>
 718           <td>The size in pixels of the dot drawn over highlighted points.
 719           <div class="tests">Tests: <a href="tests/grid_dot.html">grid_dot</a> </div>
 720           </td>
 721         </tr>
 722         <tr>
 723           <td><strong>drawPoints</strong></td>
 724           <td><code>boolean</code></td>
 725           <td><code>false</code></td>
 726           <td>Draw a small dot at each point, in addition to a line going through the point. This makes the individual data points easier to see, but can increase visual clutter in the chart.
 727           <div class="tests">Tests: <a href="tests/draw-points.html">draw-points</a> </div>
 728           </td>
 729         </tr>
 730         <tr>
 731           <td><strong>pointSize</strong></td>
 732           <td><code>interger</code></td>
 733           <td><code>1</code></td>
 734           <td>The size of the dot to draw on each point in pixels (see drawPoints). A dot is always drawn when a point is "isolated", i.e. there is a missing point on either side of it. This also controls the size of those dots.
 735           <div class="tests">Tests: <font color=red>none</font></div>
 736           </td>
 737         </tr>
 738         <tr>
 739           <td><strong>pixelsPerXLabel</strong></td>
 740           <td rowspan="2"><code>integer</code></td>
 741           <td><code>60</code></td>
 742           <td rowspan="2">Number of pixels to require between each x- and y-label. Larger values will yield a sparser axis with fewer ticks.
 743           <div class="tests">Tests: <a href="tests/spacing.html">spacing</a> </div>
 744           </td>
 745         </tr>
 746         <tr>
 747           <td><strong>pixelsPerYLabel</strong></td>
 748           <td><code>30</code></td>
 749         </tr>
 750         <tr>
 751           <td><strong>xAxisLabelWidth</strong></td>
 752           <td rowspan="2"><code>integer</code></td>
 753           <td><code></code></td>
 754           <td rowspan="2">Width (in pixels) of the x- and y-axis labels.
 755           <div class="tests">Tests: <a href="tests/customLabel.html">customLabel</a> </div>
 756           </td>
 757         </tr>
 758         <tr>
 759           <td><strong>yAxisLabelWidth</strong></td>
 760           <td><code></code></td>
 761         </tr>
 762         <tr>
 763           <td><strong>axisLabelFontSize</strong></td>
 764           <td><code>integer</code></td>
 765           <td><code>14</code></td>
 766           <td>Size of the font (in pixels) to use in the axis labels, both x- and y-axis.
 767           <div class="tests">Tests: <font color=red>none</font></div>
 768           </td>
 769         </tr>
 770         <tr>
 771           <td><strong>xAxisLabelFormatter</strong></td>
 772           <td><code>function(date, granularity)</code></td>
 773           <td><code>Dygraph.dateAxisFormatter</code></td>
 774           <td>Function to call to format values along the x axis.
 775             <div class="tests">Tests: <a href="tests/x-axis-formatter.html">xAxisLabelFormatter</a></div>
 776           </td>
 777         </tr>
 778         <tr>
 779           <td><strong>yAxisLabelFormatter</strong></td>
 780           <td><code>function(x)</code></td>
 781           <td><code>yValueFormatter</code></td>
 782           <td>
 783             Function used to format values along the Y axis. By default it uses the same as the <code>yValueFormatter</code> unless specified.
 784             <div class="tests">Tests: <a href="tests/y-axis-formatter.html">yAxisLabelFormatter</a></div>
 785           </td>
 786         </tr>
 787         <tr>
 788           <td><strong>rightGap</strong></td>
 789           <td><code>integer</code></td>
 790           <td><code></code></td>
 791           <td>Number of pixels to leave blank at the right edge of the Dygraph. This makes it easier to highlight the right-most data point.
 792           <div class="tests">Tests: <font color=red>none</font></div>
 793           </td>
 794         </tr>
 795         <tr>
 796           <td><strong>errorBars</strong></td>
 797           <td><code>boolean</code></td>
 798           <td><code>false</code></td>
 799           <td>Does the data contain standard deviations? Setting this to true alters the input format (see above).
 800           <div class="tests">Tests: <a href="tests/noise.html">noise</a> <a href="tests/customLabel.html">customLabel</a> <a href="tests/draw-points.html">draw-points</a> <a href="tests/fillGraph.html">fillGraph</a> <a href="tests/fractions.html">fractions</a> </div>
 801           </td>
 802         </tr>
 803         <tr>
 804           <td><strong>sigma</strong></td>
 805           <td><code>integer</code></td>
 806           <td><code></code></td>
 807           <td>When errorBars is set, shade this many standard deviations above/below each point.
 808           <div class="tests">Tests: <font color=red>none</font></div>
 809           </td>
 810         </tr>
 811         <tr>
 812           <td><strong>fractions</strong></td>
 813           <td><code>boolean</code></td>
 814           <td><code>false</code></td>
 815           <td>When set, attempt to parse each cell in the CSV file as "a/b", where a and b are integers. The ratio will be plotted. This allows computation of Wilson confidence intervals (see below).
 816           <div class="tests">Tests: <a href="tests/fractions.html">fractions</a> </div>
 817           </td>
 818         </tr>
 819         <tr>
 820           <td><strong>wilsonInterval</strong></td>
 821           <td><code>boolean</code></td>
 822           <td><code>true</code></td>
 823           <td>Use in conjunction with the "fractions" option. Instead of plotting +/- N standard deviations, dygraphs will compute a Wilson confidence interval and plot that. This has more reasonable behavior for ratios close to 0 or 1.
 824           <div class="tests">Tests: <font color=red>none</font></div>
 825           </td>
 826         </tr>
 827         <tr>
 828           <td><strong>customBars</strong></td>
 829           <td><code>boolean</code></td>
 830           <td><code>false</code></td>
 831           <td>When set, parse each CSV cell as "low;middle;high". Error bars will be drawn for each point between low and high, with the series itself going through middle.
 832           <div class="tests">Tests: <a href="tests/custom-bars.html">custom-bars</a> <a href="tests/zero-series.html">zero-series</a> </div>
 833           </td>
 834         </tr>
 835
 836         <tr>
 837           <td><strong>drawCallback</strong></td>
 838           <td><code>function(dygraph, is_initial)</code></td>
 839           <td><code>null</code></td>
 840           <td>When set, this callback gets called every time the dygraph is drawn. This includes the initial draw, after zooming and repeatedly while panning. The first parameter is the dygraph being drawn. The second is a boolean value indicating whether this is the initial draw.
 841           <div class="tests">Tests: <a href="tests/callback.html">callback</a> <a href="tests/synchronize.html">synchronize</a> </div>
 842           </td>
 843         </tr>
 844
 845         <tr>
 846           <td><strong>gridLineColor</strong></td>
 847           <td><code>red, blue</code></td>
 848           <td><code>rgb(128,128,128)</code></td>
 849           <td>The color of the gridlines.
 850           <div class="tests">Tests: <a href="tests/grid_dot.html">grid_dot</a> </div>
 851           </td>
 852         </tr>
 853
 854         <tr>
 855           <td><strong>highlightCallback</strong></td>
 856           <td><code>function(event, x, points)</code></td>
 857           <td><code>null</code></td>
 858           <td>When set, this callback gets called every time a new point is highlighted. The parameters are the JavaScript mousemove event, the x-coordinate of the highlighted points and an array of highlighted points: <code>[ {name: 'series', yval: y-value}, &hellip; ]</code>
 859           <div class="tests">Tests: <a href="tests/callback.html">callback</a> <a href="tests/crosshair.html">crosshair</a> </div>
 860           </td>
 861         </tr>
 862
 863         <tr>
 864           <td><strong>unhighlightCallback</strong></td>
 865           <td><code>function(event)</code></td>
 866           <td><code>null</code></td>
 867           <td>When set, this callback gets called every time the user stops highlighting any point by mousing out of the graph.  The parameter is the mouseout event.
 868             <div class="tests">Tests: <a href="tests/callback.html">callback</a> <a href="tests/crosshair.html">crosshair</a> </div>
 869           </td>
 870         </tr>
 871
 872         <tr>
 873           <td><strong>strokeWidth</strong></td>
 874           <td><code>0.5, 2.0</code></td>
 875           <td><code>1.0</code></td>
 876           <td>The width of the lines connecting data points.
 877           <div class="tests">Tests: <a href="tests/grid_dot.html">grid_dot</a> </div>
 878           </td>
 879         </tr>
 880
 881         <tr>
 882           <td><strong>width</strong></td>
 883           <td rowspan="2"><code>integer</code></td>
 884           <td><code>480</code></td>
 885           <td rowspan="2">Width/Height (in pixels) of the chart. If the container div has been explicitly sized, these attributes will be ignored.
 886           <div class="tests">Tests: <a href="tests/demo.html">demo</a> <a href="tests/link-interaction.html">link-interaction</a> <a href="tests/no-range.html">no-range</a> </div>
 887           </td>
 888         </tr>
 889         <tr>
 890           <td><strong>height</strong></td>
 891           <td><code>320</code></td>
 892         </tr>
 893
 894         <tr>
 895           <td><strong>stepPlot</strong></td>
 896           <td><code>boolean</code></td>
 897           <td><code>false</code></td>
 898           <td>
 899             When set, display the graph as a step plot instead of a line plot.
 900             <div class="tests">Tests: <a href="tests/steps.html">steps</a></div>
 901           </td>
 902         </tr>
 903
 904         <tr>
 905           <td><strong>xValueFormatter</strong></td>
 906           <td><code>function(x)</code></td>
 907           <td></td>
 908           <td>
 909             Function to provide a custom display format the X value for mouseover.
 910           </td>
 911         </tr>
 912
 913         <tr>
 914           <td><strong>yValueFormatter</strong></td>
 915           <td><code>function(x)</code></td>
 916           <td>(Round to 2 decimal places)</td>
 917           <td>
 918             Function to provide a custom display format for the Y value for mouseover.
 919             <div class="tests">Tests: <a href="tests/y-axis-formatter.html">yAxisLabelFormatter</a></div>
 920           </td>
 921         </tr>
 922
 923         <tr>
 924           <td><strong>avoidMinZero</strong></td>
 925           <td><code>boolean</code></td>
 926           <td><code>false</code></td>
 927           <td>
 928             When set, the heuristic that fixes the Y axis at zero for a data set with the minimum Y value of zero is disabled.
 929             This is particularly useful for data sets that contain many zero values, especially for step plots which may otherwise have lines not visible running along the bottom axis.
 930             <div class="tests">Tests: <a href="tests/avoidMinZero.html">avoidMinZero</a></div>
 931           </td>
 932         </tr>
 933
 934       </tbody>
 935     </table>
 936
 937     <h2>Common Gotchas</h2>
 938
 939     <p>Here are a few problems that I've frequently run into while using the dygraphs library.</p>
 940
 941     <ul>
 942       <li>If your chart doesn't display, be sure to check your browser's JavaScript error console. dygraphs makes every attempt to log errors and warnings, and these can often guide you in the right direction.</li>
 943       <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>
 944       <li>Make sure your CSV files are in the correct format. They must be of the form <code>YYYYMMDD, series1, series2, </code>&hellip; . And if you set the <code>errorBars</code> property, make sure you alternate data series and standard deviations.</li>
 945       <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 <code>align = center</code> set.</li>
 946       <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>
 947       <li>Make sure you don't have any trailing commas in your call to the Dygraph constructor or in the options parameter. Firefox, Chrome and Safari ignore these but they can cause a graph to not display in Internet Explorer.</li>
 948     </ul>
 949
 950     <h2 id="gwt">GWT Compatibility</h2>
 951     <p>There is currently no GWT wrapper around Dygraphs, however there is a class that can be used to easily load Dygraphs into the browser.  To use it, include the generated dygraph-gwt.jar file in your classpath and add the following line to your GWT module:</p>
 952
 953 <pre>
 954 &lt;inherits name=&quot;org.danvk.dygraphs&quot;/&gt;
 955 </pre>
 956
 957     <p>Call org.danvk.Dygraphs.install() when your application starts to install the JavaScript code into the browser.  You can use <a href="http://code.google.com/webtoolkit/doc/latest/DevGuideCodingBasicsJSNI.html">JSNI</a> to call Dygraphs from your GWT code, as in the example below.  The example uses the <a href="http://code.google.com/p/gwt-google-apis/wiki/VisualizationGettingStarted">Visualization API for GWT</a> and the <a href="#gviz">Dygraphs GViz API.</a></p>
 958
 959 <pre>
 960   public static native JavaScriptObject drawDygraph(Element element, DataTable dataTable, double minY, double maxY) /*-{
 961     var chart = new $wnd.Dygraph.GVizChart(element);
 962     chart.draw(dataTable,
 963       {
 964         valueRange: [minY, maxY]
 965       });
 966     return chart;
 967   }-*/;
 968 </pre>
 969
 970     <h2 id="policy">Data Policy</h2>
 971     <p>dygraphs is purely client-side JavaScript. It does not send your data to any servers &ndash; the data is processed entirely in the client's browser.</p>
 972
 973     <p style="font-size:0.8em">Created May 9, 2008 by <a href=mailto:danvdk@gmail.com>Dan Vanderkam</a></p>
 974   </div>
 975
 976
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