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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 <p>For more demos, browse the dygraph <a href="tests/">tests</a> directory.</p>
  90
  91 <h2>Usage</h2>
  92
  93 <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:
  94
  95 <pre>./generate-combined.sh</pre>
  96
  97 <p>The combined JS file is now in <code>dygraph-combined.js</code>. Here's a basic example to get things started:</p>
  98
  99 <table>
 100   <tr><th>HTML</th>
 101       <td rowspan=2><img src=arrow.gif /></td>
 102       <th>Output</th></tr>
 103 <tr>
 104 <td valign=top><pre>
 105 &lt;html&gt;
 106 &lt;head&gt;
 107 &lt;script type="text/javascript" src="combined.js"&gt;&lt;/script&gt;
 108 &lt;/head&gt;
 109 &lt;body&gt;
 110 &lt;div id="graphdiv"&gt;&lt;/div&gt;
 111 &lt;script type="text/javascript"&gt;
 112   g = new Dygraph(
 113         document.getElementById("graphdiv"),  // containing div
 114         "Date,Temperature\n" +                // CSV or path to a CSV file.
 115         "20080507,75\n" +
 116         "20080508,70\n" +
 117         "20080509,80\n",
 118       );
 119 &lt;/script&gt;
 120 &lt;/body&gt;
 121 &lt;/html&gt;
 122 </pre>
 123 </td><td valign=top>
 124   <div id="graphdiv"></div>
 125   <script type="text/javascript">
 126     g = new Dygraph(
 127         document.getElementById("graphdiv"),  // containing div
 128         "Date,Temperature\n" +                // CSV or path to a CSV file.
 129         "20080507,75\n" +
 130         "20080508,70\n" +
 131         "20080509,80\n"
 132       );
 133   </script>
 134 </td></tr></table>
 135
 136 <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>
 137
 138 <table>
 139   <tr><th>HTML</th>
 140       <td rowspan=2><img src=arrow.gif /></td>
 141       <th>Output</th></tr>
 142 <tr>
 143 <td valign=top><pre>
 144 &lt;html&gt;
 145 &lt;head&gt;
 146 &lt;script type="text/javascript" src="combined.js"&gt;&lt;/script&gt;
 147 &lt;/head&gt;
 148 &lt;body&gt;
 149 &lt;div id="graphdiv" style="width:600px; height:300px;"&gt;&lt;/div&gt;
 150 &lt;script type="text/javascript"&gt;
 151   g = new Dygraph(
 152         document.getElementById("graphdiv"),
 153         "temperatures.csv",  // path to CSV file
 154         {}                   // additional options
 155       );
 156 &lt;/script&gt;
 157 &lt;/body&gt;
 158 &lt;/html&gt;
 159 </pre>
 160 </td><td valign=top>
 161   <div id="graphdiv2" style="width:600px; height:300px;"></div>
 162   <script type="text/javascript">
 163     g2 = new Dygraph(
 164           document.getElementById("graphdiv2"),
 165           "temperatures.csv", {}
 166         );
 167   </script>
 168 </td></tr></table>
 169
 170 <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>
 171
 172 <ul>
 173   <li>The Dygraph sent off an XHR to get the temperatures.csv file.</li>
 174   <li>The labels were taken from the first line of <code>temperatures.csv</code>, which is <code>Date,High,Low</code>.</li>
 175   <li>The Dygraph automatically chose two different, easily-distinguishable colors for the two data series.</li>
 176   <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>
 177   <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>
 178   <li>The data is very spiky. A moving average would be easier to interpret.</li>
 179 </ul>
 180
 181 <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>
 182
 183 <table>
 184   <tr><th>HTML</th>
 185       <td rowspan=2><img src=arrow.gif /></td>
 186       <th>Output</th></tr>
 187 <tr>
 188 <td valign=top><pre>
 189 &lt;html&gt;
 190 &lt;head&gt;
 191 &lt;script type="text/javascript" src="combined.js"&gt;&lt;/script&gt;
 192 &lt;/head&gt;
 193 &lt;body&gt;
 194 &lt;div id="graphdiv" style="width:600px; height:300px;"&gt;&lt;/div&gt;
 195 &lt;script type="text/javascript"&gt;
 196   g = new Dygraph(
 197         document.getElementById("graphdiv"),
 198         "temperatures.csv",
 199         { rollPeriod: 7,
 200           showRoller: true,
 201         }
 202       );
 203 &lt;/script&gt;
 204 &lt;/body&gt;
 205 &lt;/html&gt;
 206 </pre>
 207 </td><td valign=top>
 208   <div id="graphdiv3" style="width:600px; height:300px;"></div>
 209   <script type="text/javascript">
 210     g3 = new Dygraph(
 211           document.getElementById("graphdiv3"),
 212           "temperatures.csv",
 213           { rollPeriod: 7,
 214             showRoller: true,
 215           }
 216         );
 217   </script>
 218 </td></tr></table>
 219
 220 <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>
 221
 222 <h2>Error Bars</h2>
 223 <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>
 224
 225 <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>
 226
 227 <table>
 228   <tr><th>HTML</th>
 229       <td rowspan=2><img src=arrow.gif /></td>
 230       <th>Output</th></tr>
 231 <tr>
 232 <td valign=top><pre>
 233 &lt;html&gt;
 234 &lt;head&gt;
 235 &lt;script type="text/javascript"
 236   src="combined.js"&gt;&lt;/script&gt;
 237 &lt;/head&gt;
 238 &lt;body&gt;
 239 &lt;div id="graphdiv"
 240  style="width:800px; height:400px;"
 241  &gt;&lt;/div&gt;
 242 &lt;script type="text/javascript"&gt;
 243 $ = document.getElementById;
 244 g = new Dygraph(
 245   $("graphdiv"),
 246   "twonormals.csv",
 247   { rollPeriod: 7,
 248     showRoller: true,
 249     errorBars: true,
 250     valueRange: [50,125]
 251   }
 252 );
 253 &lt;/script&gt;
 254 &lt;/body&gt;
 255 &lt;/html&gt;
 256 </pre>
 257 </td><td valign=top>
 258   <div id="graphdiv4" style="width:800px; height:400px;"></div>
 259   <script type="text/javascript">
 260 $ = document.getElementById;
 261 new Dygraph(
 262   document.getElementById("graphdiv4"),
 263   "twonormals.csv",
 264   { rollPeriod: 14,
 265     showRoller: true,
 266     errorBars: true,
 267     valueRange: [50, 125]
 268   }
 269 );
 270   </script>
 271 </td></tr></table>
 272
 273 <p>Things to note here:</p>
 274 <ul>
 275   <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>
 276   <li>The first line of the CSV file doesn't mention the error columns. In this case, it's just "Date,Series1,Series2".</li>
 277   <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>
 278   <li>The error bars are partially transparent. This can be seen when they overlap one another.</li>
 279 </ul>
 280
 281 <h2>One last demo</h2>
 282
 283 <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>
 284
 285 <div id=dow_chart style="width:1000px; height:400px;"></div>
 286 <script type="text/javascript">
 287   // From http://www.econstats.com/eqty/eq_d_mi_3.csv
 288   dow = new Dygraph(
 289     document.getElementById('dow_chart'),
 290     "dow.txt",
 291     {
 292       showRoller: true,
 293       customBars: true,
 294       labelsKMB: true,
 295       padding: {left:30, right:30, top:5, bottom:5}
 296     });
 297 </script>
 298 <!--
 299
 300 Here is a script to regenerate the Dow Jones plot:
 301
 302 # Get unadjusted DJIA data in a nice format:
 303 curl -O http://www.econstats.com/eqty/eq_d_mi_3.csv
 304 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
 305
 306 # Fetch and format the CPI data:
 307 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
 308 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-$2\t/g' > cpi-u.tsv
 309
 310 # Merge:
 311 join -t'       ' cpi-u.tsv monthly-djia.tsv > annotated-djia.tsv
 312 perl -ne 'BEGIN{print "Month,Nominal,Real\n"} chomp; ($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
 313
 314 -->
 315
 316
 317 <h2>Other Options</h2>
 318 <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>
 319
 320 <table class=thinborder width=1000>
 321   <tr><th>Name</th><th>Sample Value</th><th>Description</th></tr>
 322   <tr>
 323     <td><b>rollPeriod</b></td>
 324     <td><code>7</code></td>
 325     <td>Number of days over which to average data. Discussed extensively above.</td>
 326   </tr>
 327
 328   <tr>
 329     <td><b>showRoller</b></td>
 330     <td><code>true</code></td>
 331     <td>Should the rolling average period text box be shown? Default is false.</td>
 332   </tr>
 333
 334   <tr>
 335     <td><b>colors</b></td>
 336     <td><code>['red',&nbsp;'#00FF00']</code></td>
 337     <td>List of colors for the data series. These can be of the form "#AABBCC"
 338       or "rgb(255,100,200)" or "yellow", etc. If not specified, equally-spaced
 339       points around a color wheel are used.</td>
 340   </tr>
 341
 342   <tr>
 343     <td><b>colorSaturation</b></td>
 344     <td><code>1.0</code></td>
 345     <td>If <b>colors</b> is not specified, saturation of the
 346       automatically-generated data series colors. (0.0-1.0, default:
 347       1.0)</td>
 348   </tr>
 349
 350   <tr>
 351     <td><b>colorValue</b></td>
 352     <td><code>0.5</code></td>
 353     <td>If colors is not specified, value of the data series colors, as in
 354       hue/saturation/value. (0.0-1.0, default 0.5)</td>
 355   </tr>
 356
 357   <tr>
 358     <td><b>clickCallback</b></td>
 359     <td><code>function(e,date){ alert(date); }</code></td>
 360     <td>A function to call when a data point is clicked. The function should take
 361       two arguments, the event object for the click and the date that was
 362       clicked. (default null)</td>
 363   </tr>
 364
 365   <tr>
 366     <td><b>zoomCallback</b></td>
 367     <td><code>function(minDate,maxDate) {}</code></td>
 368     <td>A function to call when the zoom window is changed (either by zooming
 369     in or out). minDate and maxDate are millis since epoch.</td>
 370   </tr>
 371
 372   <tr>
 373     <td><b>strokeWidth</b></td>
 374     <td><code>2.0</code></td>
 375     <td>Width of the data lines. This can be used to increase the contrast or
 376       some graphs. (default 1.0)</td>
 377   </tr>
 378
 379   <tr>
 380     <td><b>dateWindow</b></td>
 381     <td><code>[Date.parse('2006-01-01'),<br/>
 382         (new&nbsp;Date()).valueOf()]</code></td>
 383     <td>Initially zoom in on a section of the graph. Is of the form [earliest,
 384       latest], where earliest/latest are millis since epoch.  By default, the
 385       full range of the input is shown.</td>
 386   </tr>
 387
 388   <tr>
 389     <td><b>valueRange</b></td>
 390     <td><code>[10, 110]</code></td>
 391     <td>Explicitly set the vertical range of the graph to [low, high]. By
 392       default, some clever heuristics are used (see above).</td>
 393   </tr>
 394
 395   <tr>
 396     <td><b>labelsSeparateLines</b></td>
 397     <td><code>true</code></td>
 398     <td>Put &lt;br/&gt; between lines in the label string. Often used in
 399       conjunction with <b>labelsDiv</b>. (default false)</td>
 400   </tr>
 401
 402   <tr>
 403     <td><b>labelsDiv</b></td>
 404     <td><code>document.getElementById('foo')</code></td>
 405     <td>Show data labels in an external div, rather than on the graph. (default
 406       null)</td>
 407   </tr>
 408
 409   <tr>
 410     <td><b>labelsKMB</b></td>
 411     <td><code>true</code></td>
 412     <td>Show K/M/B for thousands/millions/billions on y-axis (default
 413       false).</td>
 414   </tr>
 415
 416   <tr>
 417     <td><b>labelsDivWidth</b></td>
 418     <td>250</td>
 419     <td>Width (in pixels) of the div which shows information on the
 420     currently-highlighted points.</td>
 421   </tr>
 422
 423   <tr>
 424     <td><b>labelsDivStyles</b></td>
 425     <td>{}</td>
 426     <td>Additional styles to apply to the currently-highlighted points div. For
 427     example, { 'font-weigth': 'bold' } will make the labels bold.</td>
 428   </tr>
 429
 430   <tr>
 431     <td><b>highlightCircleSize</b></td>
 432     <td><code>3</code></td>
 433     <td>Size (in pixels) of the dot drawn over highlighted points (default 3).</td>
 434   </tr>
 435
 436   <tr>
 437     <td><b>pixelsPerXLabel</b>, <b>pixelsPerYLabel</b></td>
 438     <td>50</td>
 439     <td>Number of pixels to require between each x- and y-label. Larger values
 440     will yield a sparser axis with fewer ticks. Defaults: 60 (x-axis), 30
 441     (y-axis).</td>
 442   </tr>
 443
 444   <tr>
 445     <td><b>xAxisLabelWidth</b>, <b>yAxisLabelWidth</b></td>
 446     <td>50</td>
 447     <td>Width (in pixels) of the x- and y-axis labels.</td>
 448   </tr>
 449
 450   <tr>
 451     <td><b>axisLabelFontSize</b></td>
 452     <td>14</td>
 453     <td>Size of the font (in pixels) to use in the axis labels, both x- and
 454     y-axis.</td>
 455   </tr>
 456
 457   <tr>
 458     <td><b>rightGap</b></td>
 459     <td>5</td>
 460     <td>Number of pixels to leave blank at the right edge of the Dygraph. This
 461     makes it easier to highlight the right-most data point.</td>
 462   </tr>
 463
 464   <tr>
 465     <td><b>errorBars</b></td>
 466     <td><code>false</code></td>
 467     <td>Does the data contain standard deviations? Setting this to true alters
 468       the input format (see above). (default false)</td>
 469   </tr>
 470
 471   <tr>
 472     <td><b>sigma</b></td>
 473     <td>2</td>
 474     <td>When errorBars is set, shade this many standard deviations above/below
 475     each point.</td>
 476   </tr>
 477
 478   <tr>
 479     <td><b>fractions</b></td>
 480     <td>false</td>
 481     <td>When set, attempt to parse each cell in the CSV file as "a/b", where a
 482     and b are integers. The ratio will be plotted. This allows computation of
 483     Wilson confidence intervals (see below).</td>
 484   </tr>
 485
 486   <tr>
 487     <td><b>wilsonInterval</b></td>
 488     <td>true</td>
 489     <td>Use in conjunction with the "fractions" option. Instead of plotting +/-
 490     N standard deviations, dygraphs will compute a Wilson confidence interval
 491     and plot that. This has more reasonable behavior for ratios close to 0 or
 492     1.</td>
 493   </tr>
 494
 495   <tr>
 496     <td><b>customBars</b></td>
 497     <td>false</td>
 498     <td>When set, parse each CSV cell as "low;middle;high". Error bars will be
 499     drawn for each point between low and high, with the series itself going
 500     through middle.</td>
 501   </tr>
 502 </table>
 503
 504 <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>
 505
 506 <h2>Common Gotchas</h2>
 507 <p>Here are a few problems that I've frequently run into while using the
 508 dygraphs library.</p>
 509
 510 <ul>
 511   <li>Make sure your CSV files are readable! If your graph isn't showing up,
 512   the XMLHttpRequest for the CSV file may be failing. You can determine whether
 513   this is the case using tools like <a
 514     href="http://www.getfirebug.com/">Firebug</a>.</li>
 515
 516   <li>Make sure your CSV files are in the correct format. They must be of the
 517   form <code>YYYYMMDD,series1,series2,...</code>. And if you set the
 518   <code>errorBars</code> property, make sure you alternate data series and
 519   standard deviations.</li>
 520
 521   <li>dygraphs are not happy when placed inside a <code>&lt;center&gt;</code>
 522   tag. This applies to the CSS <code>text-align</code> property as well. If you
 523   want to center a Dygraph, put it inside a table with "align=center"
 524   set.</li>
 525
 526   <li>Don't set the <code>dateWindow</code> property to a date. It expects
 527   milliseconds since epoch, which can be obtained from a JavaScript Date
 528   object's valueOf method.</li>
 529 </ul>
 530
 531 <h2>Data Policy</h2>
 532 <p>dygraphs is purely client-side JavaScript. It does not send your data to any
 533 servers -- the data is process entirely in the client's browser.</p>
 534
 535 <p><font size=-1>Created May 9, 2008 by <a href=mailto:danvdk@gmail.com>Dan Vanderkam</a></font></p>
 536
 537 </body>
 538 </html>