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   5     <title>dygraphs JavaScript Visualization Library</title>
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   7       <script type="text/javascript" src="excanvas.js"></script>
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   9     <script type="text/javascript" src="dygraph-combined.js"></script>
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  13     <div id="nav">
  14       <h2>Documentation</h2>
  15       <ul>
  16         <li><a href="#demo">Demo</a></li>
  17         <li><a href="#usage">Usage</a></li>
  18         <li><a href="#ie">IE Compatibility</a></li>
  19         <li><a href="#gviz">GViz Data</a></li>
  20         <li><a href="#baseball">Baseball chart</a></li>
  21         <li><a href="#stock">Stock chart</a></li>
  22         <li><a href="#options">Options Reference</a></li>
  23         <li><a href="#gwt">GWT Compatibility</a></li>
  24         <li><a href="#policy">Data Policy</a></li>
  25       </ul>
  26
  27       <h2>Features</h2>
  28       <ul>
  29         <li><a href="data.html">Data Formats</a></li>
  30         <li><a href="annotations.html">Annotations</a></li>
  31       </ul>
  32
  33       <h2>Project</h2>
  34       <ul>
  35         <li><a href="http://github.com/danvk/dygraphs">Source</a></li>
  36         <li><a href="http://code.google.com/p/dygraphs/issues/">Issues</a></li>
  37         <li><a href="http://code.google.com/p/dygraphs/issues/entry">Report Bug</a></li>
  38         <li><a href="changes.html">Contribute a change</a></li>
  39         <li><a href="mailto:dygraphs-users [at] googlegroups.com">Contact</a></li>
  40       </ul>
  41
  42       <h2>Gallery</h2>
  43       <ul>
  44         <li><a href="tests/">(browse demos)</a></li>
  45         <li><a href="tests/demo.html">Basic Demo</a></li>
  46         <li><a href="tests/gviz.html">GViz Demo</a></li>
  47         <li><a href="tests/plotter.html">Equation Plotter</a></li>
  48         <li><a href="tests/perf.html">Performance Test</a></li>
  49         <li><a href="tests/annotation.html">Annotations</a></li>
  50         <li><a href="tests/annotation-gviz.html">Annotations (GViz)</a></li>
  51         <li><a href="tests/fillGraph.html">Filled Chart</a></li>
  52         <li><a href="tests/perf.html">Fractions</a></li>
  53         <li><a href="tests/visibility.html">Visibility</a></li>
  54         <li><a href="tests/label-div.html">Labels in a DIV</a></li>
  55         <li><a href="tests/numeric-axis.html">Numeric Axis</a></li>
  56         <li><a href="tests/draw-points.html">Dotted Points</a></li>
  57         <li><a href="tests/native-format.html">Native Format</a></li>
  58         <li><a href="tests/grid_dot.html">Crazy Styles</a></li>
  59         <li><a href="tests/spacing.html">Tick spacing</a></li>
  60         <li><a href="tests/callback.html">Callbacks</a></li>
  61         <li><a href="tests/crosshair.html">Crosshairs</a></li>
  62         <li><a href="tests/hourly.html">Hourly/Minutely data</a></li>
  63         <li><a href="tests/isolated-points.html">Isolated Points</a></li>
  64         <li><a href="tests/missing-data.html">Missing Data</a></li>
  65         <li><a href="tests/border.html">Bordered chart</a></li>
  66         <li><a href="tests/custom-bars.html">Custom Bars</a></li>
  67         <li><a href="tests/customLabel.html">Custom Label Styles</a></li>
  68         <li><a href="tests/dygraph.html">Minimal Example</a></li>
  69         <li><a href="tests/negative.html">Negative Numbers</a></li>
  70         <li><a href="tests/noise.html">Noisy Data</a></li>
  71         <li><a href="tests/two-series.html">Multiple Series</a></li>
  72         <li><a href="tests/highlighted-region.html">Custom Underlay / background</a></li>
  73         <li><a href="tests/zoom.html">Tests for zoom operations</a></li>
  74         <li><a href="tests/logscale.html">Log scale tests</a></li>
  75       </ul>
  76     </div>
  77
  78     <div id="content">
  79       <h1>dygraphs JavaScript Visualization Library</h1>
  80
  81       <p><a href="http://github.com/danvk/dygraphs">http://github.com/danvk/dygraphs</a></p>
  82       <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>
  83
  84       <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>
  85
  86       <h3 id="demo">A demo is worth a thousand words:</h3>
  87
  88       <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>
  89
  90       <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>
  91
  92       <div id="demodiv" style="width:800px; height:320px;"></div>
  93       <script type="text/javascript">
  94         g = new Dygraph(
  95           document.getElementById("demodiv"),
  96           "ny-vs-sf.txt",
  97           {
  98             rollPeriod: 14,
  99             showRoller: true,
 100             customBars: true,
 101             yAxisLabelWidth: 30,
 102             title: 'Temperatures in New York vs. San Francisco',
 103             ylabel: 'Temperature (F)'
 104           }
 105         );
 106       </script>
 107
 108       <h4>Some things to notice:</h4>
 109       <ul>
 110         <li>There's less seasonal temperature variation in SF than in NY.</li>
 111         <li>The difference is about 15&deg; F for SF vs. 50&deg; F for NY.</li>
 112         <li>The daily data (set rolling period to 1) is quite noisy and hides this conclusion.</li>
 113         <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>
 114         <li>There's a gap in the data for SF, when the weather station was down (zoom into October 2007 to see it).</li>
 115         <li>The bands around each point indicate average highs and lows.</li>
 116         <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>
 117       </ul>
 118
 119       <p>dygraphs allows the user to explore the data and discover these facts.</p>
 120
 121       <p>For more demos, browse the dygraph <a href="tests/">tests</a> directory.</p>
 122
 123       <h3>Features</h3>
 124       <p>Some of the features of dygraphs:</p>
 125       <ul>
 126         <li>Plots time series without using an external server or Flash</li>
 127         <li>Works in Internet Explorer (using excanvas)</li>
 128         <li>Lightweight (69kb) and responsive</li>
 129         <li>Displays values on mouseover (this makes it easily discoverable)</li>
 130         <li>Supports error bands around data series</li>
 131         <li>Interactive zoom</li>
 132         <li>Displays Annotations on the chart</li>
 133         <li>Adjustable averaging period</li>
 134         <li>Can intelligently chart fractions</li>
 135         <li>Customizable click-through actions</li>
 136         <li>Compatible with the Google Visualization API</li>
 137         <li>Intelligent defaults make it easy to use</li>
 138       </ul>
 139
 140       <h2 id="usage">Usage</h2>
 141
 142       <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>
 143
 144       <p>Here's a basic example to get things started:</p>
 145
 146       <div class="example" style="clear:both;">
 147         <div class="codeblock" style="float:left;width:400px;">
 148           <h3 style="text-align:center">HTML</h3>
 149           <code>
 150   <pre>
 151 &lt;html&gt;
 152 &lt;head&gt;
 153 &lt;script type=&quot;text/javascript&quot;
 154   src=&quot;dygraph-combined.js&quot;&gt;&lt;/script&gt;
 155 &lt;/head&gt;
 156 &lt;body&gt;
 157 &lt;div id=&quot;graphdiv&quot;&gt;&lt;/div&gt;
 158 &lt;script type=&quot;text/javascript&quot;&gt;
 159   g = new Dygraph(
 160
 161     // containing div
 162     document.getElementById(&quot;graphdiv&quot;),
 163
 164     // CSV or path to a CSV file.
 165     &quot;Date,Temperature\n&quot; +
 166     &quot;2008-05-07,75\n&quot; +
 167     &quot;2008-05-08,70\n&quot; +
 168     &quot;2008-05-09,80\n&quot;
 169
 170   );
 171 &lt;/script&gt;
 172 &lt;/body&gt;
 173 &lt;/html&gt;
 174 </pre>
 175           </code>
 176         </div>
 177         <div class="codeoutput" style="float:left;">
 178           <h3 style="text-align:center">OUTPUT</h3>
 179           <div id="graphdiv"></div>
 180           <script type="text/javascript">
 181             g = new Dygraph(
 182
 183               // containing div
 184               document.getElementById("graphdiv"),
 185
 186               // CSV or path to a CSV file.
 187               "Date,Temperature\n" +
 188               "2008-05-07,75\n" +
 189               "2008-05-08,70\n" +
 190               "2008-05-09,80\n"
 191             );
 192           </script>
 193         </div>
 194       </div>
 195
 196       <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>
 197
 198       <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>
 199
 200       <div class="example" style="clear:both;">
 201         <div class="codeblock" style="float:left;width:400px;">
 202           <h3 style="text-align:center">HTML</h3>
 203           <code>
 204 <pre>
 205 &lt;html&gt;
 206 &lt;head&gt;
 207 &lt;script type=&quot;text/javascript&quot;
 208   src=&quot;dygraph-combined.js&quot;&gt;&lt;/script&gt;
 209 &lt;/head&gt;
 210 &lt;body&gt;
 211 &lt;div id=&quot;graphdiv2&quot;
 212   style=&quot;width:500px; height:300px;&quot;&gt;&lt;/div&gt;
 213 &lt;script type=&quot;text/javascript&quot;&gt;
 214   g2 = new Dygraph(
 215     document.getElementById(&quot;graphdiv2&quot;),
 216     &quot;temperatures.csv&quot;, // path to CSV file
 217     {}          // options
 218   );
 219 &lt;/script&gt;
 220 &lt;/body&gt;
 221 &lt;/html&gt;
 222 </pre>
 223           </code>
 224         </div>
 225         <div class="codeoutput" style="float:left;">
 226           <h3 style="text-align:center">OUTPUT</h3>
 227           <div id="graphdiv2" style="width:500px; height:300px;"></div>
 228           <script type="text/javascript">
 229             g2 = new Dygraph(
 230               document.getElementById("graphdiv2"),
 231               "temperatures.csv",
 232               {}
 233             );
 234           </script>
 235         </div>
 236       </div>
 237
 238       <p style="clear:both;">The file used is <code><a href="temperatures.csv">temperatures.csv</a></code>.</p>
 239
 240       <p>There are a few things to note here:</p>
 241
 242       <ul>
 243         <li>The Dygraph sent off an XHR to get the temperatures.csv file.</li>
 244         <li>The labels were taken from the first line of <code>temperatures.csv</code>, which is <code>Date,High,Low</code>.</li>
 245         <li>The Dygraph automatically chose two different, easily-distinguishable colors for the two data series.</li>
 246         <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>
 247         <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>
 248         <li>The data is very spiky. A moving average would be easier to interpret.</li>
 249       </ul>
 250
 251       <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>
 252
 253       <div class="example" style="clear:both;">
 254         <div class="codeblock" style="float:left;width:400px;">
 255           <h3 style="text-align:center">HTML</h3>
 256           <code>
 257 <pre>
 258 &lt;html&gt;
 259 &lt;head&gt;
 260 &lt;script type=&quot;text/javascript&quot;
 261   src=&quot;dygraph-combined.js&quot;&gt;&lt;/script&gt;
 262 &lt;/head&gt;
 263 &lt;body&gt;
 264 &lt;div id=&quot;graphdiv3&quot;
 265   style=&quot;width:500px; height:300px;&quot;&gt;&lt;/div&gt;
 266 &lt;script type=&quot;text/javascript&quot;&gt;
 267   g3 = new Dygraph(
 268     document.getElementById(&quot;graphdiv3&quot;),
 269     &quot;temperatures.csv&quot;,
 270     {
 271       rollPeriod: 7,
 272       showRoller: true
 273     }
 274   );
 275 &lt;/script&gt;
 276 &lt;/body&gt;
 277 &lt;/html&gt;
 278 </pre>
 279           </code>
 280         </div>
 281         <div class="codeoutput" style="float:left;">
 282           <h3 style="text-align:center">OUTPUT</h3>
 283           <div id="graphdiv3" style="width:500px; height:300px;"></div>
 284           <script type="text/javascript">
 285             g3 = new Dygraph(
 286               document.getElementById("graphdiv3"),
 287               "temperatures.csv",
 288               {
 289                 rollPeriod: 7,
 290                 showRoller: true
 291               }
 292             );
 293           </script>
 294         </div>
 295       </div>
 296
 297       <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>
 298
 299       <h2>Error Bars</h2>
 300
 301       <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>
 302
 303       <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>
 304
 305       <div class="example" style="clear:both;">
 306         <div class="codeblock" style="float:left;width:400px;">
 307           <h3 style="text-align:center">HTML</h3>
 308           <code>
 309 <pre>
 310 &lt;html&gt;
 311 &lt;head&gt;
 312 &lt;script type=&quot;text/javascript&quot;
 313   src=&quot;combined.js&quot;&gt;&lt;/script&gt;
 314 &lt;/head&gt;
 315 &lt;body&gt;
 316 &lt;div id=&quot;graphdiv4&quot;
 317   style=&quot;width:600px; height:300px;&quot;&gt;&lt;/div&gt;
 318 &lt;script type=&quot;text/javascript&quot;&gt;
 319   g4 = new Dygraph(
 320     document.getElementById(&quot;graphdiv4&quot;),
 321     &quot;twonormals.csv&quot;,
 322     {
 323       rollPeriod: 7,
 324       showRoller: true,
 325       errorBars: true,
 326       valueRange: [50,125]
 327     }
 328   );
 329 &lt;/script&gt;
 330 &lt;/body&gt;
 331 &lt;/html&gt;
 332 </pre>
 333           </code>
 334         </div>
 335         <div class="codeoutput" style="float:left;">
 336           <h3 style="text-align:center">OUTPUT</h3>
 337           <div id="graphdiv4" style="width:600px; height:300px;"></div>
 338           <script type="text/javascript">
 339             g4 = new Dygraph(
 340               document.getElementById("graphdiv4"),
 341               "twonormals.csv",
 342               {
 343                 rollPeriod: 7,
 344                 showRoller: true,
 345                 errorBars: true,
 346                 valueRange: [50,125]
 347               }
 348             );
 349           </script>
 350         </div>
 351       </div>
 352
 353       <p style="clear:both;">Things to note here:</p>
 354
 355       <ul>
 356         <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>
 357         <li>The first line of the CSV file doesn't mention the error columns. In this case, it's just "Date,Series1,Series2".</li>
 358         <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>
 359         <li>The error bars are partially transparent. This can be seen when they overlap one another.</li>
 360       </ul>
 361
 362       <h2 id="ie">Internet Explorer Compatibility</h2>
 363
 364       <p>The dygraphs library relies heavily on the HTML5 <code>&lt;canvas&gt;</code> tag, which Microsoft Internet Explorer did not traditionally support. To use Microsoft's native canvas implementation in IE9, you need to set an HTML5 doctype on your page:</p>
 365
 366 <pre>
 367 &lt;!DOCTYPE html&gt;
 368 </pre>
 369
 370       <p>When IE9 is in HTML5 mode, dygraphs works just like in other modern browsers.</p>
 371
 372       <p>If you want to support previous versions of Internet Explorer (IE6&ndash;IE8), you'll need to include the <a href="http://code.google.com/p/explorercanvas/">excanvas</a> library, which emulates the <code>&lt;canvas&gt;</code> tag using VML. You can add excanvas by including the following snippet:</p>
 373
 374 <pre>
 375 &lt;!DOCTYPE html&gt;
 376 &lt;html&gt;
 377   &lt;head&gt;
 378     &lt;meta http-equiv="X-UA-Compatible" content="IE=EmulateIE7; IE=EmulateIE9"&gt;
 379     &lt;!--[if IE]&gt;&lt;script src="path/to/excanvas.js"&gt;&lt;/script&gt;&lt;![endif]--&gt;
 380   &lt;/head&gt;
 381 </pre>
 382
 383 <p>(This is surprisingly tricky because the HTML5 doctype breaks excanvas in IE8. See <a href="https://groups.google.com/group/dygraphs-users/browse_thread/thread/c60709e04bc7fe5f#">this discussion</a> for details.)</p>
 384
 385     <p>While VML emulation sounds like it would be slow, it works well in practice for most charts.</p>
 386
 387     <p>One common gotcha to look out for: make sure you don't have any trailing commas in parameter lists, e.g.</p>
 388
 389 <pre>
 390 new Dygraph(el, data, {
 391   showRoller: true,  // note trailing comma
 392 })</pre>
 393
 394     <p>Most browsers will ignore the trailing comma, but it will break under IE.</p>
 395
 396     <h2 id="gviz">GViz Data</h2>
 397
 398     <p>The <a
 399       href="http://code.google.com/apis/visualization/documentation/index.html">Google
 400       Visualization API</a> provides a standard interface for describing data.
 401     Once you've specified your data using this API, you can plug in any
 402     GViz-compatible visualization. dygraphs is such a visualization. In
 403     particular, it can be used as a drop-in replacement for the
 404     AnnotatedTimeline visualization used on Google Finance and other sites. To
 405     see how this works, check out the <a href="tests/annotation-gviz.html">gviz
 406       annotation demo.</a></p>
 407
 408     <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>
 409
 410     <p>Here's an example of a published gviz gadget using dygraphs:</p>
 411
 412     <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>
 413
 414     <h2 id="baseball">Charting Fractions</h2>
 415
 416     <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>
 417
 418     <ul>
 419       <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>
 420       <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>
 421     </ul>
 422
 423     <p>Fortunately, dygraphs handles both of these for you! Here's a chart and the command that generated it:</p>
 424
 425     <div style="width:750px; text-align:center; font-weight: bold; font-size: 125%;">Batting Average for Ichiro Suzuki vs. Mariners (2004)</div>
 426     <div id="baseballdiv" style="width:750px; height:300px;"></div>
 427     <script type="text/javascript">
 428       new Dygraph(
 429         document.getElementById("baseballdiv"),
 430         "suzuki-mariners.txt",
 431         {
 432           fractions: true,
 433           errorBars: true,
 434           showRoller: true,
 435           rollPeriod: 15
 436         }
 437       );
 438     </script>
 439
 440     <p>Command:</p>
 441 <pre>
 442   new Dygraph(
 443     document.getElementById(&quot;baseballdiv&quot;),
 444     &quot;suzuki-mariners.txt&quot;,
 445     {
 446       fractions: true,
 447       errorBars: true,
 448       showRoller: true,
 449       rollPeriod: 15
 450     }
 451   );
 452 </pre>
 453
 454     <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>
 455
 456     <p>A couple things to notice about this chart:</p>
 457
 458     <ul>
 459       <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>
 460       <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>
 461       <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>
 462       <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>
 463     </ul>
 464
 465     <h2 id="stock">One last demo</h2>
 466
 467     <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>
 468
 469     <div id="dow_chart" style="width:900px; height:350px;"></div>
 470     <p><b>Display: </b>
 471     <input type=checkbox id=0 onClick="stockchange(this)" checked>
 472     <label for="0"> Nominal</label>
 473     <input type=checkbox id=1 onClick="stockchange(this)" checked>
 474     <label for="1"> Real</label>
 475     <input type=checkbox id=ann onClick="annotationschange(this)" checked>
 476     <label for="ann"> Annotations</label>
 477     </p>
 478
 479     <script type="text/javascript">
 480       var stock_annotations = [
 481         {
 482           series: "Real",
 483           x: "1929-08-15",
 484           shortText: "A",
 485           text: "1929 Stock Market Peak"
 486         },
 487         {
 488           series: "Nominal",
 489           x: "1987-08-15",
 490           shortText: "B",
 491           text: "1987 Crash"
 492         },
 493         {
 494           series: "Nominal",
 495           x: "1999-12-15",
 496           shortText: "C",
 497           text: "1999 (.com) Peak"
 498         },
 499         {
 500           series: "Nominal",
 501           x: "2007-10-15",
 502           shortText: "D",
 503           text: "All-Time Market Peak"
 504         }
 505       ];
 506
 507     // From http://www.econstats.com/eqty/eq_d_mi_3.csv
 508       stockchart = new Dygraph(
 509         document.getElementById('dow_chart'),
 510         "dow.txt",
 511         {
 512           showRoller: true,
 513           customBars: true,
 514           labelsKMB: true,
 515           drawCallback: function(g, is_initial) {
 516             if (!is_initial) return;
 517             g.setAnnotations( stock_annotations );
 518           }
 519         }
 520       );
 521
 522       function stockchange(el) {
 523         stockchart.setVisibility(el.id, el.checked);
 524       }
 525
 526       function annotationschange(el) {
 527         if (el.checked) {
 528           stockchart.setAnnotations(stock_annotations);
 529         } else {
 530           stockchart.setAnnotations([]);
 531         }
 532       }
 533     </script>
 534 <!--
 535
 536 Here is a script to regenerate the Dow Jones plot:
 537
 538 # Get unadjusted DJIA data in a nice format:
 539 curl -O http://www.econstats.com/eqty/eq_d_mi_3.csv
 540 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
 541
 542 # Fetch and format the CPI data:
 543 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
 544 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-$2\t/g' > cpi-u.tsv
 545
 546 # Merge:
 547 join -t'     ' cpi-u.tsv monthly-djia.tsv > annotated-djia.tsv
 548 perl -ne 'BEGIN{print "Month,Nominal,Real\n"} chomp; ($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
 549
 550 -->
 551
 552     <h2 id="options">Other Options</h2>
 553
 554     <p>In addition to the options mentioned above (<code>showRoller</code>, <code>rollPeriod</code>, <code>errorBars</code>, <code>valueRange</code>), there are <i>many</i> others.</p>
 555
 556     <p>For a full list, see the <a href="options.html">Dygraphs Options Reference</a> page.</p>
 557
 558     <h2>Common Gotchas</h2>
 559
 560     <p>Here are a few problems that I've frequently run into while using the dygraphs library.</p>
 561
 562     <ul>
 563       <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>
 564       <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>
 565       <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>
 566       <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>
 567       <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>
 568       <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>
 569     </ul>
 570
 571     <h2 id="gwt">GWT Compatibility</h2>
 572     <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>
 573
 574 <pre>
 575 &lt;inherits name=&quot;org.danvk.dygraphs&quot;/&gt;
 576 </pre>
 577
 578     <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>
 579
 580 <pre>
 581   public static native JavaScriptObject drawDygraph(Element element, DataTable dataTable, double minY, double maxY) /*-{
 582     var chart = new $wnd.Dygraph.GVizChart(element);
 583     chart.draw(dataTable,
 584       {
 585         valueRange: [minY, maxY]
 586       });
 587     return chart;
 588   }-*/;
 589 </pre>
 590
 591     <h2 id="policy">Data Policy</h2>
 592     <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>
 593
 594     <p style="font-size:0.8em">Created May 9, 2008 by <a href=mailto:danvdk@gmail.com>Dan Vanderkam</a></p>
 595   </div>
 596
 597
 598   <!-- Google Analytics -->
 599   <script src="http://www.google-analytics.com/urchin.js" type="text/javascript"></script>
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