3 <title>dygraphs JavaScript Library
</title>
5 <script type=
"text/javascript" src=
"excanvas.js"></script>
7 <script type=
"text/javascript" src=
"dygraph-combined.js"></script>
8 <style type=
"text/css">
14 border-collapse: collapse;
16 .thinborder td, .thinborder th {
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>
30 <p>The dygraphs JavaScript library produces produces interactive, zoomable charts of time series based on CSV files.
</p>
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>
45 <li>Requires Firefox
1.5+ or Safari/WebKit
1.3+.
</li>
46 <li>Internet Explorer is poorly supported.
</li>
50 <font size=-
1>(Mouse over to highlight individual values. Click and drag to zoom. Double-click to zoom out.)
</font><br/>
52 <div id=
"demodiv" style=
"width:480px; height:320px;"></div>
54 <div id=
"status" style=
"width:200px; font-size:0.8em; padding-top:5px;"></div>
57 <script type=
"text/javascript">
59 document.getElementById(
"demodiv"),
61 var zp = function(x) { if (x <
10) return
"0"+x; else return x; };
62 var r =
"date,parabola,line,another line,sine wave\n";
63 for (var i=
1; i<=
31; i++) {
64 r +=
"200610" + zp(i);
65 r +=
"," +
10*(i*(
31-i));
67 r +=
"," +
10*(
250 -
8*i);
68 r +=
"," +
10*(
125 +
125 * Math.sin(
0.3*i));
76 labelsDiv: document.getElementById('status'),
77 labelsSeparateLines: true,
79 colors: [
"hsl(180,60,50)",
82 "rgba(50,50,200,0.4)"],
83 padding: {left:
40, right:
30, top:
15, bottom:
15}
90 <p>The DateGraph 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 <pre>./generate-combined.sh
</pre>
94 <p>The combined JS file is now in
<code>dygraph-combined.js
</code>. Here's a basic example to get things started:
</p>
98 <td rowspan=
2><img src=arrow.gif
/></td>
104 <script
type=
"text/javascript" src=
"combined.js"></script
>
107 <div
id=
"graphdiv" style=
"width:400px; height:300px;"></div
>
108 <script
type=
"text/javascript">
110 document.getElementById(
"graphdiv"), // containing div
111 function() { // function or path to CSV file.
112 return
"20080507,75\n" +
116 [
"Temperature" ], // names of data series
117 {} // additional options (see below)
124 <div id=
"graphdiv" style=
"width:400px; height:300px;"></div>
125 <script type=
"text/javascript">
127 document.getElementById(
"graphdiv"),
128 function() { // function or path to CSV file.
129 return
"20080507,75\n" +
133 [
"Temperature" ], // names of data series
134 {} // additional options
139 <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 DateGraph 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>
143 <td rowspan=
2><img src=arrow.gif
/></td>
149 <script
type=
"text/javascript" src=
"combined.js"></script
>
152 <div
id=
"graphdiv" style=
"width:600px; height:300px;"></div
>
153 <script
type=
"text/javascript">
155 document.getElementById(
"graphdiv"),
156 "temperatures.csv", // path to CSV file
157 null, // labels in top line of CSV file
165 <div id=
"graphdiv2" style=
"width:600px; height:300px;"></div>
166 <script type=
"text/javascript">
168 document.getElementById(
"graphdiv2"),
169 "temperatures.csv", null, {}
174 <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>
177 <li>Because the third parameter to the DateGraph constructor was
<code>null
</code>, the labels were taken from the first line of the data instead. The first line of
<code>temperatures.csv
</code> is
<code>Date,High,Low
</code>.
</li>
178 <li>DateGraph automatically chose two different, easily-distinguishable colors for the two data series.
</li>
179 <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>
180 <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, but in this case the vertical range is way too large.
</li>
181 <li>The data is very spiky. A moving average would be easier to interpret.
</li>
184 <p>These last two problems can be fixed by specifying the appropriate options in the fourth parameter to the DateGraph constructor. To set the number of days for a moving average, use the
<b>rollPeriod
</b> option. To set the range of the y-axis, use the
<b>valueRange
</b> option. Here's how it's done:
</p>
188 <td rowspan=
2><img src=arrow.gif
/></td>
194 <script
type=
"text/javascript" src=
"combined.js"></script
>
197 <div
id=
"graphdiv" style=
"width:600px; height:300px;"></div
>
198 <script
type=
"text/javascript">
200 document.getElementById(
"graphdiv"),
201 "temperatures.csv", null,
204 valueRange: [
25,
100]
212 <div id=
"graphdiv3" style=
"width:600px; height:300px;"></div>
213 <script type=
"text/javascript">
215 document.getElementById(
"graphdiv3"),
216 "temperatures.csv", null,
219 valueRange: [
25,
100]
225 <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>
228 <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, DateGraph will compute the standard deviation of the average at each point. (i.e.
<i>σ</i> = sqrt((
<i>σ_1
</i>^
2 +
<i>σ_2
</i>^
2 + ... +
<i>σ_n
</i>^
2)/
<i>n
</i>))
</p>
230 <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>
234 <td rowspan=
2><img src=arrow.gif
/></td>
240 <script
type=
"text/javascript"
241 src=
"combined.js"></script
>
244 <div
id=
"graphdiv"
245 style=
"width:800px; height:400px;"
247 <script
type=
"text/javascript">
248 $ = document.getElementById;
264 <div id=
"graphdiv4" style=
"width:800px; height:400px;"></div>
265 <script type=
"text/javascript">
266 $ = document.getElementById;
268 document.getElementById(
"graphdiv4"),
274 valueRange: [
50,
125]
280 <p>Things to note here:
</p>
282 <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>
283 <li>The first line of the CSV file doesn't mention the error columns. In this case, it's just
"Date,Series1,Series2".
</li>
284 <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>
285 <li>The error bars are partially transparent. This can be seen when they overlap one another.
</li>
288 <h2>One last demo
</h2>
290 <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>
292 <div id=dow_chart
style=
"width:1000px; height:400px;"></div>
293 <script type=
"text/javascript">
294 // From http://www.econstats.com/eqty/eq_d_mi_3.csv
296 document.getElementById('dow_chart'),
303 padding: {left:
30, right:
30, top:
5, bottom:
5}
308 <h2>Other Options
</h2>
309 <p>These are the options that can be passed in through the fourth parameter of the DateGraph constructor.
</p>
311 <table class=thinborder width=
1000>
312 <tr><th>Name
</th><th>Sample Value
</th><th>Description
</th></tr>
314 <td><b>rollPeriod
</b></td>
315 <td><code>7</code></td>
316 <td>Number of days over which to average data. Discussed extensively above.
</td>
318 <td><b>showRoller
</b></td>
319 <td><code>true
</code></td>
320 <td>Should the rolling average period text box be shown? Default is false.
</td>
322 <td><b>colors
</b></td>
323 <td><code>['red',
'#
00FF00']
</code></td>
324 <td>List of colors for the data series. These can be of the form
"#AABBCC"
325 or
"rgb(255,100,200)" or
"yellow", etc. If not specified, equally-spaced
326 points around a color wheel are used.
</td>
328 <td><b>colorSaturation
</b></td>
329 <td><code>1.0</code></td>
330 <td>If
<b>colors
</b> is not specified, saturation of the
331 automatically-generated data series colors. (
0.0-
1.0, default:
334 <td><b>colorValue
</b></td>
335 <td><code>0.5</code></td>
336 <td>If colors is not specified, value of the data series colors, as in
337 hue/saturation/value. (
0.0-
1.0, default
0.5)
</td>
339 <td><b>clickCallback
</b></td>
340 <td><code>function(e,date){ alert(date); }
</code></td>
341 <td>A function to call when a data point is clicked. The function should take
342 two arguments, the event object for the click and the date that was
343 clicked. (default null)
</td>
345 <td><b>errorBars
</b></td>
346 <td><code>false
</code></td>
347 <td>Does the data contain standard deviations? Setting this to true alters
348 the input format (see above). (default false)
</td>
350 <td><b>strokeWidth
</b></td>
351 <td><code>2.0</code></td>
352 <td>Width of the data lines. This can be used to increase the contrast or
353 some graphs. (default
1.0)
</td>
355 <td><b>dateWindow
</b></td>
356 <td><code>[(new
Date('
2006-
01-
01')).valueOf(),
<br/>
357 (new
Date()).valueOf()]
</code></td>
358 <td>Initially zoom in on a section of the graph. Is of the form [earliest,
359 latest], where earliest/latest are millis since epoch. By default, the
360 full range of the input is shown.
</td>
362 <td><b>valueRange
</b></td>
363 <td><code>[
10,
110]
</code></td>
364 <td>Explicitly set the vertical range of the graph to [low, high]. By
365 default, some clever heuristics are used (see above).
</td>
367 <td><b>minTickSize
</b></td>
368 <td><code>1</code</td>
369 <td>The difference between ticks on the y-axis can be greater than or equal
370 to this, but no less. If you set it to
1, for instance, you'll never get
371 nonintegral gaps between ticks.
</td>
373 <td><b>labelsSeparateLines
</b></td>
374 <td><code>true
</code></td>
375 <td>Put
<br/
> between lines in the label string. Often used in
376 conjunction with
<b>labelsDiv
</b>. (default false)
</td>
378 <td><b>labelsDiv
</b></td>
379 <td><code>document.getElementById('foo')
</code></td>
380 <td>Show data labels in an external div, rather than on the graph. (default
383 <td><b>labelsKMB
</b></td>
384 <td><code>true
</code></td>
385 <td>Show K/M/B for thousands/millions/billions on y-axis (default
389 <td><b>padding
</b></td>
390 <td><code>{left:
40, right:
30,
<br/>top:
5,
391 bottom:
15}
</code></td>
392 <td>Adds extra pixels of padding around the graph. Sometimes a dygraph
393 gets clipped by surrounding text (see the Demo at the top of this page).
394 Setting this property appropriately will fix this problem.
</td>
398 <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. DateGraph will override some of these (e.g. strokeColor), but others may be useful. The
<code>padding
</code> property is an example of this.
</p>
400 <h2>Common Gotchas
</h2>
401 <p>Here are a few problems that I've frequently run into while using the
402 dygraphs library.
</p>
405 <li>Make sure your CSV files are readable! If your graph isn't showing up,
406 the XMLHttpRequest for the CSV file may be failing. You can determine whether
407 this is the case using tools like
<a
408 href=
"http://www.getfirebug.com/">Firebug
</a>.
</li>
410 <li>Make sure your CSV files are in the correct format. They must be of the
411 form
<code>YYYYMMDD,series1,series2,...
</code>. If you're specifying the
412 names of each data series in the CSV file itself, make sure that you pass
413 <code>null
</code> as the third parameter to the DateGraph constructor to let
414 the library know that. And if you set the
<code>errorBars
</code> property,
415 make sure you alternate data series and standard deviations.
</li>
417 <li>dygraphs are not happy when placed inside a
<code><center
></code>
418 tag. This applies to the CSS
<code>text-align
</code> property as well. If you
419 want to center a DateGraph, put it inside a table with
"align=center"
422 <li>If you specify the
<code>colors
</code> property or name the data series
423 using the third parameter of the DateGraph constructor, make sure the number
424 of data series agree in all places:
<code>colors
</code>, third parameter and
425 in each line of the CSV file itself.
</li>
427 <li>Don't set the
<code>dateWindow
</code> property to a date. It expects
428 milliseconds since epoch, which can be obtained from a JavaScript Date
429 object's valueOf method.
</li>
432 <p><font size=-
1>Created May
9,
2008 by
<a href=mailto:danvdk@gmail.com
>Dan Vanderkam
</a></font></p>