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.
</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>
41 <li>Compatible with the Google Visualization API
</li>
46 <li>Requires Firefox
1.5+ or Safari/WebKit
1.3+.
</li>
47 <li>Internet Explorer is poorly supported.
</li>
51 <font size=-
1>(Mouse over to highlight individual values. Click and drag to zoom. Double-click to zoom out.)
</font><br/>
53 <div id=
"demodiv" style=
"width:480px; height:320px;"></div>
55 <div id=
"status" style=
"width:200px; font-size:0.8em; padding-top:5px;"></div>
58 <script type=
"text/javascript">
60 document.getElementById(
"demodiv"),
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));
68 r +=
"," +
10*(
250 -
8*i);
69 r +=
"," +
10*(
125 +
125 * Math.sin(
0.3*i));
77 labelsDiv: document.getElementById('status'),
78 labelsSeparateLines: true,
80 colors: [
"hsl(180,60,50)",
83 "rgba(50,50,200,0.4)"],
84 padding: {left:
40, right:
30, top:
15, bottom:
15},
92 <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 <pre>./generate-combined.sh
</pre>
96 <p>The combined JS file is now in
<code>dygraph-combined.js
</code>. Here's a basic example to get things started:
</p>
100 <td rowspan=
2><img src=arrow.gif
/></td>
106 <script
type=
"text/javascript" src=
"combined.js"></script
>
109 <div
id=
"graphdiv"></div
>
110 <script
type=
"text/javascript">
112 document.getElementById(
"graphdiv"), // containing div
113 "Date,Temperature\n" + // CSV or path to a CSV file.
123 <div id=
"graphdiv"></div>
124 <script type=
"text/javascript">
126 document.getElementById(
"graphdiv"), // containing div
127 "Date,Temperature\n" + // CSV or path to a CSV file.
135 <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>
139 <td rowspan=
2><img src=arrow.gif
/></td>
145 <script
type=
"text/javascript" src=
"combined.js"></script
>
148 <div
id=
"graphdiv" style=
"width:600px; height:300px;"></div
>
149 <script
type=
"text/javascript">
151 document.getElementById(
"graphdiv"),
152 "temperatures.csv", // path to CSV file
153 {} // additional options
160 <div id=
"graphdiv2" style=
"width:600px; height:300px;"></div>
161 <script type=
"text/javascript">
163 document.getElementById(
"graphdiv2"),
164 "temperatures.csv", {}
169 <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>
172 <li>The Dygraph sent off an XHR to get the temperatures.csv file.
</li>
173 <li>The labels were taken from the first line of
<code>temperatures.csv
</code>, which is
<code>Date,High,Low
</code>.
</li>
174 <li>The Dygraph automatically chose two different, easily-distinguishable colors for the two data series.
</li>
175 <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>
176 <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>
177 <li>The data is very spiky. A moving average would be easier to interpret.
</li>
180 <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>
184 <td rowspan=
2><img src=arrow.gif
/></td>
190 <script
type=
"text/javascript" src=
"combined.js"></script
>
193 <div
id=
"graphdiv" style=
"width:600px; height:300px;"></div
>
194 <script
type=
"text/javascript">
196 document.getElementById(
"graphdiv"),
207 <div id=
"graphdiv3" style=
"width:600px; height:300px;"></div>
208 <script type=
"text/javascript">
210 document.getElementById(
"graphdiv3"),
219 <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>
222 <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>σ</i> = sqrt((
<i>σ_1
</i>^
2 +
<i>σ_2
</i>^
2 + ... +
<i>σ_n
</i>^
2)/
<i>n
</i>))
</p>
224 <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>
228 <td rowspan=
2><img src=arrow.gif
/></td>
234 <script
type=
"text/javascript"
235 src=
"combined.js"></script
>
238 <div
id=
"graphdiv"
239 style=
"width:800px; height:400px;"
241 <script
type=
"text/javascript">
242 $ = document.getElementById;
257 <div id=
"graphdiv4" style=
"width:800px; height:400px;"></div>
258 <script type=
"text/javascript">
259 $ = document.getElementById;
261 document.getElementById(
"graphdiv4"),
266 valueRange: [
50,
125]
272 <p>Things to note here:
</p>
274 <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>
275 <li>The first line of the CSV file doesn't mention the error columns. In this case, it's just
"Date,Series1,Series2".
</li>
276 <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>
277 <li>The error bars are partially transparent. This can be seen when they overlap one another.
</li>
280 <h2>One last demo
</h2>
282 <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 <div id=dow_chart
style=
"width:1000px; height:400px;"></div>
285 <script type=
"text/javascript">
286 // From http://www.econstats.com/eqty/eq_d_mi_3.csv
288 document.getElementById('dow_chart'),
294 padding: {left:
30, right:
30, top:
5, bottom:
5}
299 Here is a script to regenerate the Dow Jones plot:
301 # Get unadjusted DJIA data in a nice format:
302 curl -O http://www.econstats.com/eqty/eq_d_mi_3.csv
303 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 # Fetch and format the CPI data:
306 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
307 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
310 join -t' ' cpi-u.tsv monthly-djia.tsv
> annotated-djia.tsv
311 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
316 <h2>Other Options
</h2>
317 <p>These are the options that can be passed in through the optional third parameter of the Dygraph constructor.
</p>
319 <table class=thinborder width=
1000>
320 <tr><th>Name
</th><th>Sample Value
</th><th>Description
</th></tr>
322 <td><b>rollPeriod
</b></td>
323 <td><code>7</code></td>
324 <td>Number of days over which to average data. Discussed extensively above.
</td>
326 <td><b>showRoller
</b></td>
327 <td><code>true
</code></td>
328 <td>Should the rolling average period text box be shown? Default is false.
</td>
330 <td><b>colors
</b></td>
331 <td><code>['red',
'#
00FF00']
</code></td>
332 <td>List of colors for the data series. These can be of the form
"#AABBCC"
333 or
"rgb(255,100,200)" or
"yellow", etc. If not specified, equally-spaced
334 points around a color wheel are used.
</td>
336 <td><b>colorSaturation
</b></td>
337 <td><code>1.0</code></td>
338 <td>If
<b>colors
</b> is not specified, saturation of the
339 automatically-generated data series colors. (
0.0-
1.0, default:
342 <td><b>colorValue
</b></td>
343 <td><code>0.5</code></td>
344 <td>If colors is not specified, value of the data series colors, as in
345 hue/saturation/value. (
0.0-
1.0, default
0.5)
</td>
347 <td><b>clickCallback
</b></td>
348 <td><code>function(e,date){ alert(date); }
</code></td>
349 <td>A function to call when a data point is clicked. The function should take
350 two arguments, the event object for the click and the date that was
351 clicked. (default null)
</td>
353 <td><b>errorBars
</b></td>
354 <td><code>false
</code></td>
355 <td>Does the data contain standard deviations? Setting this to true alters
356 the input format (see above). (default false)
</td>
358 <td><b>strokeWidth
</b></td>
359 <td><code>2.0</code></td>
360 <td>Width of the data lines. This can be used to increase the contrast or
361 some graphs. (default
1.0)
</td>
363 <td><b>dateWindow
</b></td>
364 <td><code>[(new
Date('
2006-
01-
01')).valueOf(),
<br/>
365 (new
Date()).valueOf()]
</code></td>
366 <td>Initially zoom in on a section of the graph. Is of the form [earliest,
367 latest], where earliest/latest are millis since epoch. By default, the
368 full range of the input is shown.
</td>
370 <td><b>valueRange
</b></td>
371 <td><code>[
10,
110]
</code></td>
372 <td>Explicitly set the vertical range of the graph to [low, high]. By
373 default, some clever heuristics are used (see above).
</td>
375 <td><b>minTickSize
</b></td>
376 <td><code>1</code</td>
377 <td>The difference between ticks on the y-axis can be greater than or equal
378 to this, but no less. If you set it to
1, for instance, you'll never get
379 nonintegral gaps between ticks.
</td>
381 <td><b>labelsSeparateLines
</b></td>
382 <td><code>true
</code></td>
383 <td>Put
<br/
> between lines in the label string. Often used in
384 conjunction with
<b>labelsDiv
</b>. (default false)
</td>
386 <td><b>labelsDiv
</b></td>
387 <td><code>document.getElementById('foo')
</code></td>
388 <td>Show data labels in an external div, rather than on the graph. (default
391 <td><b>labelsKMB
</b></td>
392 <td><code>true
</code></td>
393 <td>Show K/M/B for thousands/millions/billions on y-axis (default
397 <td><b>padding
</b></td>
398 <td><code>{left:
40, right:
30,
<br/>top:
5,
399 bottom:
15}
</code></td>
400 <td>Adds extra pixels of padding around the graph. Sometimes a dygraph
401 gets clipped by surrounding text (see the Demo at the top of this page).
402 Setting this property appropriately will fix this problem.
</td>
406 <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>
408 <h2>Common Gotchas
</h2>
409 <p>Here are a few problems that I've frequently run into while using the
410 dygraphs library.
</p>
413 <li>Make sure your CSV files are readable! If your graph isn't showing up,
414 the XMLHttpRequest for the CSV file may be failing. You can determine whether
415 this is the case using tools like
<a
416 href=
"http://www.getfirebug.com/">Firebug
</a>.
</li>
418 <li>Make sure your CSV files are in the correct format. They must be of the
419 form
<code>YYYYMMDD,series1,series2,...
</code>. And if you set the
420 <code>errorBars
</code> property, make sure you alternate data series and
421 standard deviations.
</li>
423 <li>dygraphs are not happy when placed inside a
<code><center
></code>
424 tag. This applies to the CSS
<code>text-align
</code> property as well. If you
425 want to center a Dygraph, put it inside a table with
"align=center"
428 <li>Don't set the
<code>dateWindow
</code> property to a date. It expects
429 milliseconds since epoch, which can be obtained from a JavaScript Date
430 object's valueOf method.
</li>
433 <p><font size=-
1>Created May
9,
2008 by
<a href=mailto:danvdk@gmail.com
>Dan Vanderkam
</a></font></p>