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  26     <p><span style="font-size:28pt;">dygraphs JavaScript Library</span><br/>
  27     <a href="http://code.google.com/p/dygraphs/">code.google.com/p/dygraphs</a></p>
  28   </center>
  29
  30 <p>The dygraphs JavaScript library produces produces interactive, zoomable charts of time series.</p>
  31
  32 <h3>Features</h3>
  33 <ul>
  34   <li>Plots time series without using an external server or Flash</li>
  35   <li>Supports multiple data series</li>
  36   <li>Supports error bands around data series</li>
  37   <li>Displays values on mouseover</li>
  38   <li>Interactive zoom</li>
  39   <li>Adjustable averaging period</li>
  40   <li>Customizable click-through actions</li>
  41   <li>Compatible with the Google Visualization API</li>
  42 </ul>
  43
  44 <h3>Caveats</h3>
  45 <ul>
  46   <li>Requires Firefox 1.5+ or Safari/WebKit 1.3+.</li>
  47   <li>Internet Explorer is poorly supported.</li>
  48 </ul>
  49
  50 <h2>Demo</h2>
  51 <font size=-1>(Mouse over to highlight individual values. Click and drag to zoom. Double-click to zoom out.)</font><br/>
  52 <table><tr><td>
  53 <div id="demodiv" style="width:480px; height:320px;"></div>
  54 </td><td valign=top>
  55 <div id="status" style="width:200px; font-size:0.8em; padding-top:5px;"></div>
  56 </td>
  57 </tr></table>
  58 <script type="text/javascript">
  59   g = new DateGraph(
  60           document.getElementById("demodiv"),
  61           function() {
  62             var zp = function(x) { if (x < 10) return "0"+x; else return x; };
  63             var r = "date,parabola,line,another line,sine wave\n";
  64             for (var i=1; i<=31; i++) {
  65             r += "200610" + zp(i);
  66             r += "," + 10*(i*(31-i));
  67             r += "," + 10*(8*i);
  68             r += "," + 10*(250 - 8*i);
  69             r += "," + 10*(125 + 125 * Math.sin(0.3*i));
  70             r += "\n";
  71             }
  72             return r;
  73           },
  74           null,
  75           {
  76             rollPeriod: 1,
  77             labelsDiv: document.getElementById('status'),
  78             labelsSeparateLines: true,
  79             labelsKMB: true,
  80             colors: ["hsl(180,60,50)",
  81                      "rgb(255,100,100)",
  82                      "#00DD55",
  83                      "rgba(50,50,200,0.4)"],
  84             padding: {left: 40, right: 30, top: 15, bottom: 15},
  85           }
  86       );
  87 </script>
  88
  89 <h2>Usage</h2>
  90
  91 <p>The dygraphs library depends on two other JS libraries: <a href="http://www.mochikit.com/">MochiKit</a> and <a href="http://www.liquidx.net/plotkit/">PlotKit</a>. Rather than tracking down copies of these libraries, I recommend using a packed version of dygraphs that combines all three libraries into a single JS file. Either grab this file from dygraph project's <a href="http://code.google.com/p/dygraphs/downloads/list">downloads</a> page or create it yourself by <a href="http://code.google.com/p/dygraphs/source/checkout">checking out</a> a copy of the code and running:
  92
  93 <pre>./generate-combined.sh</pre>
  94
  95 <p>The combined JS file is now in <code>dygraph-combined.js</code>. Here's a basic example to get things started:</p>
  96
  97 <table>
  98   <tr><th>HTML</th>
  99       <td rowspan=2><img src=arrow.gif /></td>
 100       <th>Output</th></tr>
 101 <tr>
 102 <td valign=top><pre>
 103 &lt;html&gt;
 104 &lt;head&gt;
 105 &lt;script type="text/javascript" src="combined.js"&gt;&lt;/script&gt;
 106 &lt;/head&gt;
 107 &lt;body&gt;
 108 &lt;div id="graphdiv"&gt;&lt;/div&gt;
 109 &lt;script type="text/javascript"&gt;
 110   g = new Dygraph(
 111         document.getElementById("graphdiv"),  // containing div
 112         "Date,Temperature\n" +                // CSV or path to a CSV file.
 113         "20080507,75\n" +
 114         "20080508,70\n" +
 115         "20080509,80\n",
 116       );
 117 &lt;/script&gt;
 118 &lt;/body&gt;
 119 &lt;/html&gt;
 120 </pre>
 121 </td><td valign=top>
 122   <div id="graphdiv"></div>
 123   <script type="text/javascript">
 124     g = new Dygraph(
 125         document.getElementById("graphdiv"),  // containing div
 126         "Date,Temperature\n" +                // CSV or path to a CSV file.
 127         "20080507,75\n" +
 128         "20080508,70\n" +
 129         "20080509,80\n"
 130       );
 131   </script>
 132 </td></tr></table>
 133
 134 <p>In order to keep this example self-contained, the second parameter is a function that returns CSV data. These lines <i>must</i> begin with a date in the form <i>YYYYMMDD</i>. In most applications, it makes more sense to include a CSV file instead. If the second parameter to the constructor is a string, it will be interpreted as the path to a CSV file. The Dygraph will perform an XMLHttpRequest to retrieve this file and display the data when it becomes available. Make sure your CSV file is readable and serving from a place that understands XMLHttpRequest's! In particular, you cannot specify a CSV file using <code>"file:///"</code>. Here's an example: (data from <a href="http://www.wunderground.com/history/airport/KNUQ/2007/1/1/CustomHistory.html?dayend=31&monthend=12&yearend=2007&req_city=NA&req_state=NA&req_statename=NA">Weather Underground</a>)</p>
 135
 136 <table>
 137   <tr><th>HTML</th>
 138       <td rowspan=2><img src=arrow.gif /></td>
 139       <th>Output</th></tr>
 140 <tr>
 141 <td valign=top><pre>
 142 &lt;html&gt;
 143 &lt;head&gt;
 144 &lt;script type="text/javascript" src="combined.js"&gt;&lt;/script&gt;
 145 &lt;/head&gt;
 146 &lt;body&gt;
 147 &lt;div id="graphdiv" style="width:600px; height:300px;"&gt;&lt;/div&gt;
 148 &lt;script type="text/javascript"&gt;
 149   g = new Dygraph(
 150         document.getElementById("graphdiv"),
 151         "temperatures.csv",  // path to CSV file
 152         {}                   // additional options
 153       );
 154 &lt;/script&gt;
 155 &lt;/body&gt;
 156 &lt;/html&gt;
 157 </pre>
 158 </td><td valign=top>
 159   <div id="graphdiv2" style="width:600px; height:300px;"></div>
 160   <script type="text/javascript">
 161     g2 = new Dygraph(
 162           document.getElementById("graphdiv2"),
 163           "temperatures.csv", {}
 164         );
 165   </script>
 166 </td></tr></table>
 167
 168 <p>Click <a href="temperatures.csv">here</a> to view the <code>temperatures.csv</code> file. There are a few things to note here:</p>
 169
 170 <ul>
 171   <li>The Dygraph sent off an XHR to get the temperatures.csv file.</li>
 172   <li>The labels were taken from the first line of <code>temperatures.csv</code>, which is <code>Date,High,Low</code>.</li>
 173   <li>The Dygraph automatically chose two different, easily-distinguishable colors for the two data series.</li>
 174   <li>The labels on the x-axis have switched from days to months. If you zoom in, they'll switch to weeks and then days.</li>
 175   <li>Some heuristics are used to determine a good vertical range for the data. The idea is to make all the data visible and have human-friendly values on the axis (i.e. 200 instead of 193.4). Generally this works well.</li>
 176   <li>The data is very spiky. A moving average would be easier to interpret.</li>
 177 </ul>
 178
 179 <p>This problem can be fixed by specifying the appropriate options in the "additional options" parameter to the Dygraph constructor. To set the number of days for a moving average, use the <b>rollPeriod</b> option. Here's how it's done:</p>
 180
 181 <table>
 182   <tr><th>HTML</th>
 183       <td rowspan=2><img src=arrow.gif /></td>
 184       <th>Output</th></tr>
 185 <tr>
 186 <td valign=top><pre>
 187 &lt;html&gt;
 188 &lt;head&gt;
 189 &lt;script type="text/javascript" src="combined.js"&gt;&lt;/script&gt;
 190 &lt;/head&gt;
 191 &lt;body&gt;
 192 &lt;div id="graphdiv" style="width:600px; height:300px;"&gt;&lt;/div&gt;
 193 &lt;script type="text/javascript"&gt;
 194   g = new Dygraph(
 195         document.getElementById("graphdiv"),
 196         "temperatures.csv",
 197         { rollPeriod: 7,
 198           showRoller: true,
 199         }
 200       );
 201 &lt;/script&gt;
 202 &lt;/body&gt;
 203 &lt;/html&gt;
 204 </pre>
 205 </td><td valign=top>
 206   <div id="graphdiv3" style="width:600px; height:300px;"></div>
 207   <script type="text/javascript">
 208     g3 = new Dygraph(
 209           document.getElementById("graphdiv3"),
 210           "temperatures.csv",
 211           { rollPeriod: 7,
 212             showRoller: true,
 213           }
 214         );
 215   </script>
 216 </td></tr></table>
 217
 218 <p>A rolling average can be set using the text box in the lower left-hand corner of the graph (the showRoller attribute is what makes this appear).</p>
 219
 220 <h2>Error Bars</h2>
 221 <p>Another significant feature of the dygraphs library is the ability to display error bars around data series. One standard deviation must be specified for each data point. A +/-<i>n</i> sigma band will be drawn around the data series at that point. If a moving average is being displayed, dygraphs will compute the standard deviation of the average at each point. (i.e. <i>&sigma;</i> = sqrt((<i>&sigma;_1</i>^2 + <i>&sigma;_2</i>^2 + ... + <i>&sigma;_n</i>^2)/<i>n</i>))</p>
 222
 223 <p>Here's a demonstration. There are two data series. One is <code>N(100,10)</code> with a standard deviation of 10 specified at each point. The other is <code>N(80,20)</code> with a standard deviation of 20 specified at each point. The CSV file was generated using Octave and can be viewed <a href="twonormals.csv">here</a>.</p>
 224
 225 <table>
 226   <tr><th>HTML</th>
 227       <td rowspan=2><img src=arrow.gif /></td>
 228       <th>Output</th></tr>
 229 <tr>
 230 <td valign=top><pre>
 231 &lt;html&gt;
 232 &lt;head&gt;
 233 &lt;script type="text/javascript"
 234   src="combined.js"&gt;&lt;/script&gt;
 235 &lt;/head&gt;
 236 &lt;body&gt;
 237 &lt;div id="graphdiv"
 238  style="width:800px; height:400px;"
 239  &gt;&lt;/div&gt;
 240 &lt;script type="text/javascript"&gt;
 241 $ = document.getElementById;
 242 g = new Dygraph(
 243   $("graphdiv"),
 244   "twonormals.csv",
 245   { rollPeriod: 7,
 246     showRoller: true,
 247     errorBars: true,
 248     valueRange: [50,125]
 249   }
 250 );
 251 &lt;/script&gt;
 252 &lt;/body&gt;
 253 &lt;/html&gt;
 254 </pre>
 255 </td><td valign=top>
 256   <div id="graphdiv4" style="width:800px; height:400px;"></div>
 257   <script type="text/javascript">
 258 $ = document.getElementById;
 259 new Dygraph(
 260   document.getElementById("graphdiv4"),
 261   "twonormals.csv",
 262   { rollPeriod: 14,
 263     showRoller: true,
 264     errorBars: true,
 265     valueRange: [50, 125]
 266   }
 267 );
 268   </script>
 269 </td></tr></table>
 270
 271 <p>Things to note here:</p>
 272 <ul>
 273   <li>The <b>errorBars</b> option affects both the interpretation of the CSV file and the display of the graph. When <b>errorBars</b> is set to true, each line is interpreted as <i>YYYYMMDD</i>,<i>A</i>,<i>sigma_A</i>,<i>B</i>,<i>sigma_B</i>,...</li>
 274   <li>The first line of the CSV file doesn't mention the error columns. In this case, it's just "Date,Series1,Series2".</li>
 275   <li>The averaging visibly affects the error bars. This is most clear if you crank up the rolling period to something like 100 days. For the earliest dates, there won't be 100 data points to average so the signal will be noisier. The error bars get smaller like sqrt(N) going forward in time until there's a full 100 points to average.</li>
 276   <li>The error bars are partially transparent. This can be seen when they overlap one another.</li>
 277 </ul>
 278
 279 <h2>One last demo</h2>
 280
 281 <p>This chart shows monthly closes of the Dow Jones Industrial Average, both in nominal and real (i.e. adjusted for inflation) dollars. The shaded areas show its monthly high and low. CPI values with a base from 1982-84 are used to adjust for inflation.</p>
 282
 283 <div id=dow_chart style="width:1000px; height:400px;"></div>
 284 <script type="text/javascript">
 285   // From http://www.econstats.com/eqty/eq_d_mi_3.csv
 286   dow = new Dygraph(
 287     document.getElementById('dow_chart'),
 288     "dow.txt",
 289     {
 290       showRoller: true,
 291       customBars: true,
 292       labelsKMB: true,
 293       padding: {left:30, right:30, top:5, bottom:5}
 294     });
 295 </script>
 296 <!--
 297
 298 Here is a script to regenerate the Dow Jones plot:
 299
 300 # Get unadjusted DJIA data in a nice format:
 301 curl -O http://www.econstats.com/eqty/eq_d_mi_3.csv
 302 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
 303
 304 # Fetch and format the CPI data:
 305 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
 306 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-$2\t/g' > cpi-u.tsv
 307
 308 # Merge:
 309 join -t'       ' cpi-u.tsv monthly-djia.tsv > annotated-djia.tsv
 310 perl -ne 'BEGIN{print "Month,Nominal,Real\n"} chomp; ($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
 311
 312 -->
 313
 314
 315 <h2>Other Options</h2>
 316 <p>These are the options that can be passed in through the optional third parameter of the Dygraph constructor.</p>
 317
 318 <table class=thinborder width=1000>
 319   <tr><th>Name</th><th>Sample Value</th><th>Description</th></tr>
 320   <tr>
 321     <td><b>rollPeriod</b></td>
 322     <td><code>7</code></td>
 323     <td>Number of days over which to average data. Discussed extensively above.</td>
 324   </tr>
 325
 326   <tr>
 327     <td><b>showRoller</b></td>
 328     <td><code>true</code></td>
 329     <td>Should the rolling average period text box be shown? Default is false.</td>
 330   </tr>
 331
 332   <tr>
 333     <td><b>colors</b></td>
 334     <td><code>['red',&nbsp;'#00FF00']</code></td>
 335     <td>List of colors for the data series. These can be of the form "#AABBCC"
 336       or "rgb(255,100,200)" or "yellow", etc. If not specified, equally-spaced
 337       points around a color wheel are used.</td>
 338   </tr>
 339
 340   <tr>
 341     <td><b>colorSaturation</b></td>
 342     <td><code>1.0</code></td>
 343     <td>If <b>colors</b> is not specified, saturation of the
 344       automatically-generated data series colors. (0.0-1.0, default:
 345       1.0)</td>
 346   </tr>
 347
 348   <tr>
 349     <td><b>colorValue</b></td>
 350     <td><code>0.5</code></td>
 351     <td>If colors is not specified, value of the data series colors, as in
 352       hue/saturation/value. (0.0-1.0, default 0.5)</td>
 353   </tr>
 354
 355   <tr>
 356     <td><b>clickCallback</b></td>
 357     <td><code>function(e,date){ alert(date); }</code></td>
 358     <td>A function to call when a data point is clicked. The function should take
 359       two arguments, the event object for the click and the date that was
 360       clicked. (default null)</td>
 361   </tr>
 362
 363   <tr>
 364     <td><b>zoomCallback</b></td>
 365     <td><code>function(minDate,maxDate) {}</code></td>
 366     <td>A function to call when the zoom window is changed (either by zooming
 367     in or out). minDate and maxDate are millis since epoch.</td>
 368   </tr>
 369
 370   <tr>
 371     <td><b>strokeWidth</b></td>
 372     <td><code>2.0</code></td>
 373     <td>Width of the data lines. This can be used to increase the contrast or
 374       some graphs. (default 1.0)</td>
 375   </tr>
 376
 377   <tr>
 378     <td><b>dateWindow</b></td>
 379     <td><code>[Date.parse('2006-01-01'),<br/>
 380         (new&nbsp;Date()).valueOf()]</code></td>
 381     <td>Initially zoom in on a section of the graph. Is of the form [earliest,
 382       latest], where earliest/latest are millis since epoch.  By default, the
 383       full range of the input is shown.</td>
 384   </tr>
 385
 386   <tr>
 387     <td><b>valueRange</b></td>
 388     <td><code>[10, 110]</code></td>
 389     <td>Explicitly set the vertical range of the graph to [low, high]. By
 390       default, some clever heuristics are used (see above).</td>
 391   </tr>
 392
 393   <tr>
 394     <td><b>labelsSeparateLines</b></td>
 395     <td><code>true</code></td>
 396     <td>Put &lt;br/&gt; between lines in the label string. Often used in
 397       conjunction with <b>labelsDiv</b>. (default false)</td>
 398   </tr>
 399
 400   <tr>
 401     <td><b>labelsDiv</b></td>
 402     <td><code>document.getElementById('foo')</code></td>
 403     <td>Show data labels in an external div, rather than on the graph. (default
 404       null)</td>
 405   </tr>
 406
 407   <tr>
 408     <td><b>labelsKMB</b></td>
 409     <td><code>true</code></td>
 410     <td>Show K/M/B for thousands/millions/billions on y-axis (default
 411       false).</td>
 412   </tr>
 413
 414   <tr>
 415     <td><b>labelsDivWidth</b></td>
 416     <td>250</td>
 417     <td>Width (in pixels) of the div which shows information on the
 418     currently-highlighted points.</td>
 419   </tr>
 420
 421   <tr>
 422     <td><b>labelsDivStyles</b></td>
 423     <td>{}</td>
 424     <td>Additional styles to apply to the currently-highlighted points div. For
 425     example, { 'font-weigth': 'bold' } will make the labels bold.</td>
 426   </tr>
 427
 428   <tr>
 429     <td><b>highlightCircleSize</b></td>
 430     <td><code>3</code></td>
 431     <td>Size (in pixels) of the dot drawn over highlighted points (default 3).</td>
 432   </tr>
 433
 434   <tr>
 435     <td><b>pixelsPerXLabel</b>, <b>pixelsPerYLabel</b></td>
 436     <td>50</td>
 437     <td>Number of pixels to require between each x- and y-label. Larger values
 438     will yield a sparser axis with fewer ticks. Defaults: 60 (x-axis), 30
 439     (y-axis).</td>
 440   </tr>
 441
 442   <tr>
 443     <td><b>xAxisLabelWidth</b>, <b>yAxisLabelWidth</b></td>
 444     <td>50</td>
 445     <td>Width (in pixels) of the x- and y-axis labels.</td>
 446   </tr>
 447
 448   <tr>
 449     <td><b>axisLabelFontSize</b></td>
 450     <td>14</td>
 451     <td>Size of the font (in pixels) to use in the axis labels, both x- and
 452     y-axis.</td>
 453   </tr>
 454
 455   <tr>
 456     <td><b>rightGap</b></td>
 457     <td>5</td>
 458     <td>Number of pixels to leave blank at the right edge of the Dygraph. This
 459     makes it easier to highlight the right-most data point.</td>
 460   </tr>
 461
 462   <tr>
 463     <td><b>errorBars</b></td>
 464     <td><code>false</code></td>
 465     <td>Does the data contain standard deviations? Setting this to true alters
 466       the input format (see above). (default false)</td>
 467   </tr>
 468
 469   <tr>
 470     <td><b>sigma</b></td>
 471     <td>2</td>
 472     <td>When errorBars is set, shade this many standard deviations above/below
 473     each point.</td>
 474   </tr>
 475
 476   <tr>
 477     <td><b>fractions</b></td>
 478     <td>false</td>
 479     <td>When set, attempt to parse each cell in the CSV file as "a/b", where a
 480     and b are integers. The ratio will be plotted. This allows computation of
 481     Wilson confidence intervals (see below).</td>
 482   </tr>
 483
 484   <tr>
 485     <td><b>wilsonInterval</b></td>
 486     <td>true</td>
 487     <td>Use in conjunction with the "fractions" option. Instead of plotting +/-
 488     N standard deviations, dygraphs will compute a Wilson confidence interval
 489     and plot that. This has more reasonable behavior for ratios close to 0 or
 490     1.</td>
 491   </tr>
 492
 493   <tr>
 494     <td><b>customBars</b></td>
 495     <td>false</td>
 496     <td>When set, parse each CSV cell as "low;middle;high". Error bars will be
 497     drawn for each point between low and high, with the series itself going
 498     through middle.</td>
 499   </tr>
 500 </table>
 501
 502 <p>Any options you specify also get passed on to PlotKit's <a href="http://media.liquidx.net/js/plotkit-doc/PlotKit.Renderer.html">Renderer</a> class. dygraphs will override some of these (e.g. strokeColor), but others may be useful. The <code>padding</code> property is an example of this.</p>
 503
 504 <h2>Common Gotchas</h2>
 505 <p>Here are a few problems that I've frequently run into while using the
 506 dygraphs library.</p>
 507
 508 <ul>
 509   <li>Make sure your CSV files are readable! If your graph isn't showing up,
 510   the XMLHttpRequest for the CSV file may be failing. You can determine whether
 511   this is the case using tools like <a
 512     href="http://www.getfirebug.com/">Firebug</a>.</li>
 513
 514   <li>Make sure your CSV files are in the correct format. They must be of the
 515   form <code>YYYYMMDD,series1,series2,...</code>. And if you set the
 516   <code>errorBars</code> property, make sure you alternate data series and
 517   standard deviations.</li>
 518
 519   <li>dygraphs are not happy when placed inside a <code>&lt;center&gt;</code>
 520   tag. This applies to the CSS <code>text-align</code> property as well. If you
 521   want to center a Dygraph, put it inside a table with "align=center"
 522   set.</li>
 523
 524   <li>Don't set the <code>dateWindow</code> property to a date. It expects
 525   milliseconds since epoch, which can be obtained from a JavaScript Date
 526   object's valueOf method.</li>
 527 </ul>
 528
 529 <p><font size=-1>Created May 9, 2008 by <a href=mailto:danvdk@gmail.com>Dan Vanderkam</a></font></p>
 530
 531 </body>
 532 </html>