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  52 <ul>
  53 <li><b>Documentation</b>
  54   <ul>
  55   <li><a href="#demo">Demo</a>
  56   <li><a href="#usage">Usage</a>
  57   <li><a href="#stock">Stock chart</a>
  58   <li><a href="#options">Options Reference</a>
  59   <li><a href="#policy">Data Policy</a>
  60   </ul>
  61
  62 <li><b>Project</b>
  63   <ul>
  64   <li><a href="http://github.com/danvk/dygraphs">Source</a>
  65   <li><a href="http://code.google.com/p/dygraphs/issues/">Issues</a>
  66   <li><a href="http://code.google.com/p/dygraphs/issues/entry">Report Bug</a>
  67   <li><a href="mailto:danvdk [at] gmail">Contact</a>
  68   </ul>
  69
  70
  71 <li><b>Gallery</b>
  72   <ul>
  73   <li><a href="tests/demo.html">Basic Demo</a>
  74   <li><a href="tests/gviz.html">GViz Demo</a>
  75   <li><a href="tests/plotter.html">Equation Plotter</a>
  76   <li><a href="tests/perf.html">Performance Test</a>
  77
  78   <li><a href="tests/label-div.html">Labels in a DIV</a>
  79   <li><a href="tests/numeric-axis.html">Numeric Axis</a>
  80   <li><a href="tests/draw-points.html">Dotted Points</a>
  81
  82   <li><a href="tests/native-format.html">Native Format</a>
  83   <li><a href="tests/grid_dot.html">Crazy Styles</a>
  84   <li><a href="tests/spacing.html">Tick spacing</a>
  85   <li><a href="tests/callback.html">Callbacks</a>
  86   <li><a href="tests/crosshair.html">Crosshairs</a>
  87   <li><a href="tests/hourly.html">Hourly/Minutely data</a>
  88
  89   <li><a href="tests/isolated-points.html">Isolated Points</a>
  90   <li><a href="tests/missing-data.html">Missing Data</a>
  91
  92   <li><a href="tests/border.html">Bordered chart</a>
  93   <li><a href="tests/custom-bars.html">Custom Bars</a>
  94   <li><a href="tests/customLabel.html">Custom Label Styles</a>
  95   <li><a href="tests/dygraph.html">Minimal Example</a>
  96   <li><a href="tests/negative.html">Negative Numbers</a>
  97   <li><a href="tests/noise.html">Noisy Data</a>
  98   <li><a href="tests/two-series.html">Multiple Series</a>
  99   </ul>
 100 </ul>
 101 </div>
 102
 103 <div id="content">
 104 <p><span style="font-size:28pt;">dygraphs JavaScript Visualization Library</span><br/>
 105 <a href="http://github.com/danvk/dygraphs">http://github.com/danvk/dygraphs</a><br/>
 106 See <a href="tests/">gallery</a> and <a href="http://code.google.com/p/dygraphs/issues/">open issues</a></p>
 107
 108 <p>The dygraphs JavaScript library 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>
 109
 110 <h3>Features</h3>
 111 <ul>
 112   <li>Plots time series without using an external server or Flash</li>
 113   <li>Supports error bands around data series</li>
 114   <li>Displays values on mouseover (this makes it easily discoverable)</li>
 115   <li>Interactive zoom</li>
 116   <li>Adjustable averaging period</li>
 117   <li>Customizable click-through actions</li>
 118   <li>Compatible with the Google Visualization API</li>
 119   <li>Works in Internet Explorer (using excanvas)</li>
 120   <li>Intelligent defaults make it easy to use</li>
 121   <li>Lightweight (45kb) and responsive</li>
 122 </ul>
 123
 124 <a name="demo"><h2>Demo</h2>
 125 <p><font size=-1>(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.)</font></p>
 126 <div id="title" style="width:800px; text-align:center; font-weight: bold; font-size: 125%;">Temperatures in New York vs. San Francisco</div>
 127 <div id="demodiv" style="width:800px; height:320px;"></div>
 128 <script type="text/javascript">
 129   g = new Dygraph(
 130           document.getElementById("demodiv"),
 131           "ny-vs-sf.txt",
 132           {
 133             rollPeriod: 14,
 134             showRoller: true,
 135             customBars: true,
 136             yAxisLabelWidth: 30
 137           }
 138       );
 139 </script>
 140
 141 <p>Some things to notice:</p>
 142 <ul>
 143 <li>There's less seasonal temperature variation in SF than in NY.
 144 <li>The difference is about 15&deg; F for SF vs. 50&deg; F for NY.
 145 <li>The daily data (set rolling period to 1) is quite noisy and hides this conclusion.
 146 <li>Using a 14-day moving average makes it clearer. A 100-day rolling period averages out nearly all the specifics from the data.
 147 <li>There's a gap in the data for SF, when the weather station was down (zoom into October 2007 to see it).
 148 <li>The bands around each point indicate average highs and lows.
 149 <li>There is a <i>lot</i> 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.
 150 </ul>
 151
 152 <p>For more demos, browse the dygraph <a href="tests/">tests</a> directory.</p>
 153
 154 <a name="usage"><h2>Usage</h2>
 155
 156 <p>To use dygraphs, include the <code>dygraph-combined.js</code> JavaScript file and instantiate a <code>Dygraph</code> object.</p>
 157
 158 <p>Here's a basic example to get things started:</p>
 159
 160 <table>
 161   <tr><th>HTML</th>
 162       <td rowspan=2><img src=arrow.gif /></td>
 163       <th>Output</th></tr>
 164 <tr>
 165 <td valign=top><pre>
 166 &lt;html&gt;
 167 &lt;head&gt;
 168 &lt;script type="text/javascript"
 169   src="dygraph-combined.js"&gt;&lt;/script&gt;
 170 &lt;/head&gt;
 171 &lt;body&gt;
 172 &lt;div id="graphdiv"&gt;&lt;/div&gt;
 173 &lt;script type="text/javascript"&gt;
 174   g = new Dygraph(
 175         // containing div
 176         document.getElementById("graphdiv"),
 177         // CSV or path to a CSV file.
 178         "Date,Temperature\n" +
 179         "2008-05-07,75\n" +
 180         "2008-05-08,70\n" +
 181         "2008-05-09,80\n"
 182       );
 183 &lt;/script&gt;
 184 &lt;/body&gt;
 185 &lt;/html&gt;
 186 </pre>
 187 </td><td valign=top>
 188   <div id="graphdiv"></div>
 189 </td></tr></table>
 190
 191 <script type="text/javascript">
 192   g1 = new Dygraph(
 193        document.getElementById("graphdiv"),  // containing div
 194        "Date,Temperature\n" +                // CSV or path to a CSV file.
 195        "2008-05-07,75\n" +
 196        "2008-05-08,70\n" +
 197        "2008-05-09,80\n"
 198      );
 199 </script>
 200
 201 <p>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 the its container to a reasonable default, calculates appropriate axis ranges and tick marks and draws the graph.</p>
 202
 203 <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&monthend=12&yearend=2007&req_city=NA&req_state=NA&req_statename=NA">Weather Underground</a>)</p>
 204
 205 <table>
 206   <tr><th>HTML</th>
 207       <td rowspan=2><img src=arrow.gif /></td>
 208       <th>Output</th></tr>
 209 <tr>
 210 <td valign=top><pre>
 211 &lt;html&gt;
 212 &lt;head&gt;
 213 &lt;script type="text/javascript"
 214   src="dygraph-combined.js"&gt;&lt;/script&gt;
 215 &lt;/head&gt;
 216 &lt;body&gt;
 217 &lt;div id="graphdiv"
 218   style="width:500px; height:300px;"&gt;&lt;/div&gt;
 219 &lt;script type="text/javascript"&gt;
 220   new Dygraph(
 221     document.getElementById("graphdiv"),
 222     "temperatures.csv",  // path to CSV file
 223     {}                   // options
 224   );
 225 &lt;/script&gt;
 226 &lt;/body&gt;
 227 &lt;/html&gt;
 228 </pre>
 229 </td><td valign=top>
 230   <div id="graphdiv2" style="width:500px; height:300px;"></div>
 231 </td></tr></table>
 232
 233 <script type="text/javascript">
 234   g2 = new Dygraph(
 235         document.getElementById("graphdiv2"),
 236         "temperatures.csv", {}
 237       );
 238 </script>
 239
 240 <p>Click <a href="temperatures.csv">here</a> to view the <code>temperatures.csv</code> file. There are a few things to note here:</p>
 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 <table>
 254   <tr><th>HTML</th>
 255       <td rowspan=2><img src=arrow.gif /></td>
 256       <th>Output</th></tr>
 257 <tr>
 258 <td valign=top><pre>
 259 &lt;html&gt;
 260 &lt;head&gt;
 261 &lt;script type="text/javascript"
 262   src="dygraph-combined.js"&gt;&lt;/script&gt;
 263 &lt;/head&gt;
 264 &lt;body&gt;
 265 &lt;div id="graphdiv"
 266   style="width:500px; height:300px;"&gt;&lt;/div&gt;
 267 &lt;script type="text/javascript"&gt;
 268   g = new Dygraph(
 269         document.getElementById("graphdiv"),
 270         "temperatures.csv",
 271         { rollPeriod: 7,
 272           showRoller: true,
 273         }
 274       );
 275 &lt;/script&gt;
 276 &lt;/body&gt;
 277 &lt;/html&gt;
 278 </pre>
 279 </td><td valign=top>
 280   <div id="graphdiv3" style="width:500px; height:300px;"></div>
 281 </td></tr></table>
 282
 283 <script type="text/javascript">
 284   g3 = new Dygraph(
 285         document.getElementById("graphdiv3"),
 286         "temperatures.csv",
 287         { rollPeriod: 7,
 288           showRoller: true });
 289 </script>
 290
 291 <p>A rolling average can be set using the text box in the lower left-hand corner of the graph (the showRoller attribute is what makes this appear). Also note that we've explicitly set the size of the chart div.</p>
 292
 293 <h2>Error Bars</h2>
 294 <p>Another significant feature of the dygraphs library is the ability to display error bars around data series. One standard deviation must be specified for each data point. A +/-<i>n</i> sigma band will be drawn around the data series at that point. If a moving average is being displayed, dygraphs will compute the standard deviation of the average at each point. (i.e. <i>&sigma;</i> = sqrt((<i>&sigma;_1</i>^2 + <i>&sigma;_2</i>^2 + ... + <i>&sigma;_n</i>^2)/<i>n</i>))</p>
 295
 296 <p>Here's a demonstration. There are two data series. One is <code>N(100,10)</code> with a standard deviation of 10 specified at each point. The other is <code>N(80,20)</code> with a standard deviation of 20 specified at each point. The CSV file was generated using Octave and can be viewed <a href="twonormals.csv">here</a>.</p>
 297
 298 <table>
 299   <tr><th>HTML</th>
 300       <td rowspan=2><img src=arrow.gif /></td>
 301       <th>Output</th></tr>
 302 <tr>
 303 <td valign=top><pre>
 304 &lt;html&gt;
 305 &lt;head&gt;
 306 &lt;script type="text/javascript"
 307   src="combined.js"&gt;&lt;/script&gt;
 308 &lt;/head&gt;
 309 &lt;body&gt;
 310 &lt;div id="graphdiv"
 311  style="width:600px; height:300px;"
 312  &gt;&lt;/div&gt;
 313 &lt;script type="text/javascript"&gt;
 314 $ = document.getElementById;
 315 g = new Dygraph(
 316   $("graphdiv"),
 317   "twonormals.csv",
 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 </td><td valign=top>
 329   <div id="graphdiv4" style="width:600px; height:300px;"></div>
 330 </td></tr></table>
 331
 332 <script type="text/javascript">
 333 $ = document.getElementById;
 334 new Dygraph(
 335   document.getElementById("graphdiv4"),
 336   "twonormals.csv",
 337   { rollPeriod: 14,
 338     showRoller: true,
 339     errorBars: true,
 340     valueRange: [50, 125]
 341   }
 342 );
 343 </script>
 344
 345 <p>Things to note here:</p>
 346 <ul>
 347   <li>The <b>errorBars</b> option affects both the interpretation of the CSV file and the display of the graph. When <b>errorBars</b> is set to true, each line is interpreted as <i>YYYYMMDD</i>,<i>A</i>,<i>sigma_A</i>,<i>B</i>,<i>sigma_B</i>,...</li>
 348   <li>The first line of the CSV file doesn't mention the error columns. In this case, it's just "Date,Series1,Series2".</li>
 349   <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>
 350   <li>The error bars are partially transparent. This can be seen when they overlap one another.</li>
 351 </ul>
 352
 353 <a name="stock"><h2>One last demo</h2>
 354
 355 <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>
 356
 357 <div id=dow_chart style="width:900px; height:350px;"></div>
 358 <script type="text/javascript">
 359   // From http://www.econstats.com/eqty/eq_d_mi_3.csv
 360   dow = new Dygraph(
 361     document.getElementById('dow_chart'),
 362     "dow.txt",
 363     {
 364       showRoller: true,
 365       customBars: true,
 366       labelsKMB: true });
 367 </script>
 368 <!--
 369
 370 Here is a script to regenerate the Dow Jones plot:
 371
 372 # Get unadjusted DJIA data in a nice format:
 373 curl -O http://www.econstats.com/eqty/eq_d_mi_3.csv
 374 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
 375
 376 # Fetch and format the CPI data:
 377 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
 378 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-$2\t/g' > cpi-u.tsv
 379
 380 # Merge:
 381 join -t'       ' cpi-u.tsv monthly-djia.tsv > annotated-djia.tsv
 382 perl -ne 'BEGIN{print "Month,Nominal,Real\n"} chomp; ($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
 383
 384 -->
 385
 386
 387 <a name="options">
 388 <h2>Other Options</h2>
 389 <p>These are the options that can be passed in through the optional third parameter of the Dygraph constructor. To see demonstrations of many of these options, browse the <a href="tests/">dygraphs tests</a> directory.</p>
 390
 391 <table class=thinborder width=900>
 392   <tr><th>Name</th><th>Sample Value</th><th>Description</th></tr>
 393   <tr>
 394     <td><b>includeZero</b></td>
 395     <td><code>true, false</code></td>
 396     <td>Usually, dygraphs will use the range of the data plus some padding to
 397     set the range of the y-axis. If this option is set, the y-axis will always
 398     include zero, typically as the lowest value. This can be used to avoid
 399     exaggerating the variance in the data.</td>
 400   </tr>
 401
 402   <tr>
 403     <td><b>rollPeriod</b></td>
 404     <td><code>7</code></td>
 405     <td>Number of days over which to average data. Discussed extensively above.</td>
 406   </tr>
 407
 408   <tr>
 409     <td><b>showRoller</b></td>
 410     <td><code>true</code></td>
 411     <td>Should the rolling average period text box be shown? Default is false.</td>
 412   </tr>
 413
 414   <tr>
 415     <td><b>colors</b></td>
 416     <td><code>['red',&nbsp;'#00FF00']</code></td>
 417     <td>List of colors for the data series. These can be of the form "#AABBCC"
 418       or "rgb(255,100,200)" or "yellow", etc. If not specified, equally-spaced
 419       points around a color wheel are used.</td>
 420   </tr>
 421
 422   <tr>
 423     <td><b>colorSaturation</b></td>
 424     <td><code>1.0</code></td>
 425     <td>If <b>colors</b> is not specified, saturation of the
 426       automatically-generated data series colors. (0.0-1.0, default:
 427       1.0)</td>
 428   </tr>
 429
 430   <tr>
 431     <td><b>colorValue</b></td>
 432     <td><code>0.5</code></td>
 433     <td>If colors is not specified, value of the data series colors, as in
 434       hue/saturation/value. (0.0-1.0, default 0.5)</td>
 435   </tr>
 436
 437   <tr>
 438     <td><b>clickCallback</b></td>
 439     <td><code>function(e,date){ alert(date); }</code></td>
 440     <td>A function to call when a data point is clicked. The function should take
 441       two arguments, the event object for the click and the date that was
 442       clicked. (default null)</td>
 443   </tr>
 444
 445   <tr>
 446     <td><b>zoomCallback</b></td>
 447     <td><code>function(minDate,maxDate) {}</code></td>
 448     <td>A function to call when the zoom window is changed (either by zooming
 449     in or out). minDate and maxDate are millis since epoch.</td>
 450   </tr>
 451
 452   <tr>
 453     <td><b>strokeWidth</b></td>
 454     <td><code>2.0</code></td>
 455     <td>Width of the data lines. This can be used to increase the contrast or
 456       some graphs. (default 1.0)</td>
 457   </tr>
 458
 459   <tr>
 460     <td><b>dateWindow</b></td>
 461     <td><code>[Date.parse('2006-01-01'),<br/>
 462         (new&nbsp;Date()).valueOf()]</code></td>
 463     <td>Initially zoom in on a section of the graph. Is of the form [earliest,
 464       latest], where earliest/latest are millis since epoch.  By default, the
 465       full range of the input is shown.</td>
 466   </tr>
 467
 468   <tr>
 469     <td><b>valueRange</b></td>
 470     <td><code>[10, 110]</code></td>
 471     <td>Explicitly set the vertical range of the graph to [low, high]. By
 472       default, some clever heuristics are used (see above).</td>
 473   </tr>
 474
 475   <tr>
 476     <td><b>labelsSeparateLines</b></td>
 477     <td><code>true</code></td>
 478     <td>Put &lt;br/&gt; between lines in the label string. Often used in
 479       conjunction with <b>labelsDiv</b>. (default false)</td>
 480   </tr>
 481
 482   <tr>
 483     <td><b>labelsDiv</b></td>
 484     <td><code>document.getElementById('foo')</code></td>
 485     <td>Show data labels in an external div, rather than on the graph. (default
 486       null)</td>
 487   </tr>
 488
 489   <tr>
 490     <td><b>labelsKMB</b></td>
 491     <td><code>true</code></td>
 492     <td>Show K/M/B for thousands/millions/billions on y-axis (default
 493       false).</td>
 494   </tr>
 495
 496   <tr>
 497     <td><b>labelsDivWidth</b></td>
 498     <td>250</td>
 499     <td>Width (in pixels) of the div which shows information on the
 500     currently-highlighted points.</td>
 501   </tr>
 502
 503   <tr>
 504     <td><b>labelsDivStyles</b></td>
 505     <td>{}</td>
 506     <td>Additional styles to apply to the currently-highlighted points div. For
 507     example, { 'font-weigth': 'bold' } will make the labels bold.</td>
 508   </tr>
 509
 510   <tr>
 511     <td><b>highlightCircleSize</b></td>
 512     <td><code>3</code></td>
 513     <td>Size (in pixels) of the dot drawn over highlighted points (default 3).</td>
 514   </tr>
 515
 516   <tr>
 517     <td><b>drawPoints</b></td>
 518     <td><code>false</code></td>
 519     <td>Draw a small dot at each point, in addition to a line going through
 520     the point. This makes the individual data points easier to see, but can
 521     increase visual clutter in the chart. Default: false</td>
 522   </tr>
 523
 524   <tr>
 525     <td><b>pointSize</b></td>
 526     <td><code>1.0</code></td>
 527     <td>The size of the dot to draw on each point in pixels (see
 528     drawPoints). A dot is always drawn when a point is "isolated", i.e.
 529     there is a missing point on either side of it. This also controls the
 530     size of those dots.</td>
 531   </tr>
 532
 533   <tr>
 534     <td><b>pixelsPerXLabel</b>, <b>pixelsPerYLabel</b></td>
 535     <td>50</td>
 536     <td>Number of pixels to require between each x- and y-label. Larger values
 537     will yield a sparser axis with fewer ticks. Defaults: 60 (x-axis), 30
 538     (y-axis).</td>
 539   </tr>
 540
 541   <tr>
 542     <td><b>xAxisLabelWidth</b>, <b>yAxisLabelWidth</b></td>
 543     <td>50</td>
 544     <td>Width (in pixels) of the x- and y-axis labels.</td>
 545   </tr>
 546
 547   <tr>
 548     <td><b>axisLabelFontSize</b></td>
 549     <td>14</td>
 550     <td>Size of the font (in pixels) to use in the axis labels, both x- and
 551     y-axis.</td>
 552   </tr>
 553
 554   <tr>
 555     <td><b>rightGap</b></td>
 556     <td>5</td>
 557     <td>Number of pixels to leave blank at the right edge of the Dygraph. This
 558     makes it easier to highlight the right-most data point.</td>
 559   </tr>
 560
 561   <tr>
 562     <td><b>errorBars</b></td>
 563     <td><code>false</code></td>
 564     <td>Does the data contain standard deviations? Setting this to true alters
 565       the input format (see above). (default false)</td>
 566   </tr>
 567
 568   <tr>
 569     <td><b>sigma</b></td>
 570     <td>2</td>
 571     <td>When errorBars is set, shade this many standard deviations above/below
 572     each point.</td>
 573   </tr>
 574
 575   <tr>
 576     <td><b>fractions</b></td>
 577     <td>false</td>
 578     <td>When set, attempt to parse each cell in the CSV file as "a/b", where a
 579     and b are integers. The ratio will be plotted. This allows computation of
 580     Wilson confidence intervals (see below).</td>
 581   </tr>
 582
 583   <tr>
 584     <td><b>wilsonInterval</b></td>
 585     <td>true</td>
 586     <td>Use in conjunction with the "fractions" option. Instead of plotting +/-
 587     N standard deviations, dygraphs will compute a Wilson confidence interval
 588     and plot that. This has more reasonable behavior for ratios close to 0 or
 589     1.</td>
 590   </tr>
 591
 592   <tr>
 593     <td><b>customBars</b></td>
 594     <td>false</td>
 595     <td>When set, parse each CSV cell as "low;middle;high". Error bars will be
 596     drawn for each point between low and high, with the series itself going
 597     through middle.</td>
 598   </tr>
 599 </table>
 600
 601 <h2>Common Gotchas</h2>
 602 <p>Here are a few problems that I've frequently run into while using the
 603 dygraphs library.</p>
 604
 605 <ul>
 606   <li>Make sure your CSV files are readable! If your graph isn't showing up,
 607   the XMLHttpRequest for the CSV file may be failing. You can determine whether
 608   this is the case using tools like <a
 609     href="http://www.getfirebug.com/">Firebug</a>.</li>
 610
 611   <li>Make sure your CSV files are in the correct format. They must be of the
 612   form <code>YYYYMMDD,series1,series2,...</code>. And if you set the
 613   <code>errorBars</code> property, make sure you alternate data series and
 614   standard deviations.</li>
 615
 616   <li>dygraphs are not happy when placed inside a <code>&lt;center&gt;</code>
 617   tag. This applies to the CSS <code>text-align</code> property as well. If you
 618   want to center a Dygraph, put it inside a table with "align=center"
 619   set.</li>
 620
 621   <li>Don't set the <code>dateWindow</code> property to a date. It expects
 622   milliseconds since epoch, which can be obtained from a JavaScript Date
 623   object's valueOf method.</li>
 624
 625   <li>Make sure you don't have any trailing commas in your call to the Dygraph
 626   constructor or in the options parameter. Firefox, Chrome and Safari ignore
 627   these but they can cause a graph to not display in Internet Explorer.</li>
 628 </ul>
 629
 630 <a name="policy">
 631 <h2>Data Policy</h2>
 632 <p>dygraphs is purely client-side JavaScript. It does not send your data to any
 633 servers -- the data is processed entirely in the client's browser.</p>
 634
 635 <p><font size=-1>Created May 9, 2008 by <a href=mailto:danvdk@gmail.com>Dan Vanderkam</a></font></p>
 636
 637 </div>
 638
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