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