dygraphs JavaScript Library
- code.google.com/p/dygraphs
The dygraphs JavaScript library produces produces interactive, zoomable charts of time series.
- -| - - | - - | -
It allows users to explore and interpret dense data sets. Here's how it works:
+ +new Dygraph(div, "ny-vs-sf.txt", {
+ legend: 'always',
+ title: 'NYC vs. SF',
+ showRoller: true,
+ rollPeriod: 14,
+ customBars: true,
+ ylabel: 'Temperature (F)',
+});
+ For more demos, browse the dygraph tests directory.
-The dygraphs library depends on two other JS libraries: MochiKit and PlotKit. 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 downloads page or create it yourself by checking out a copy of the code and running: - -
./generate-combined.sh- -
The combined JS file is now in dygraph-combined.js. Here's a basic example to get things started:
| HTML | - |
- Output |
|---|---|---|
-<html>
-<head>
-<script type="text/javascript" src="combined.js"></script>
-</head>
-<body>
-<div id="graphdiv"></div>
-<script type="text/javascript">
- g = new Dygraph(
- document.getElementById("graphdiv"), // containing div
- "Date,Temperature\n" + // CSV or path to a CSV file.
- "20080507,75\n" +
- "20080508,70\n" +
- "20080509,80\n",
- );
-</script>
-</body>
-</html>
-
- | - - |
In order to keep this example self-contained, the second parameter is a function that returns CSV data. These lines must begin with a date in the form YYYYMMDD. 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 "file:///". Here's an example: (data from Weather Underground)
| HTML | - |
- Output |
|---|---|---|
-<html>
-<head>
-<script type="text/javascript" src="combined.js"></script>
-</head>
-<body>
-<div id="graphdiv" style="width:600px; height:300px;"></div>
-<script type="text/javascript">
- g = new Dygraph(
- document.getElementById("graphdiv"),
- "temperatures.csv", // path to CSV file
- {} // additional options
- );
-</script>
-</body>
-</html>
-
- | - - - |
Click here to view the temperatures.csv file. There are a few things to note here:
temperatures.csv, which is Date,High,Low.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 rollPeriod option. Here's how it's done:
- -| HTML | - |
- Output |
|---|---|---|
-<html>
-<head>
-<script type="text/javascript" src="combined.js"></script>
-</head>
-<body>
-<div id="graphdiv" style="width:600px; height:300px;"></div>
-<script type="text/javascript">
- g = new Dygraph(
- document.getElementById("graphdiv"),
- "temperatures.csv",
- { rollPeriod: 7,
- showRoller: true,
- }
- );
-</script>
-</body>
-</html>
-
- | - - - |
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).
- -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 +/-n 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. σ = sqrt((σ_1^2 + σ_2^2 + ... + σ_n^2)/n))
- -Here's a demonstration. There are two data series. One is N(100,10) with a standard deviation of 10 specified at each point. The other is N(80,20) with a standard deviation of 20 specified at each point. The CSV file was generated using Octave and can be viewed here.
| HTML | - |
- Output |
|---|---|---|
-<html>
-<head>
-<script type="text/javascript"
- src="combined.js"></script>
-</head>
-<body>
-<div id="graphdiv"
- style="width:800px; height:400px;"
- ></div>
-<script type="text/javascript">
-$ = document.getElementById;
-g = new Dygraph(
- $("graphdiv"),
- "twonormals.csv",
- { rollPeriod: 7,
- showRoller: true,
- errorBars: true,
- valueRange: [50,125]
- }
-);
-</script>
-</body>
-</html>
-
- | - - - |
Things to note here:
-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.
- - - - - - -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 dygraphs tests directory.
- -| Name | Sample Value | Description |
|---|---|---|
| includeZero | -true, false |
- Usually, dygraphs will use the range of the data plus some padding to - set the range of the y-axis. If this option is set, the y-axis will always - include zero, typically as the lowest value. This can be used to avoid - exaggerating the variance in the data. | -
| rollPeriod | -7 |
- Number of days over which to average data. Discussed extensively above. | -
| showRoller | -true |
- Should the rolling average period text box be shown? Default is false. | -
| colors | -['red', '#00FF00'] |
- List of colors for the data series. These can be of the form "#AABBCC" - or "rgb(255,100,200)" or "yellow", etc. If not specified, equally-spaced - points around a color wheel are used. | -
| colorSaturation | -1.0 |
- If colors is not specified, saturation of the - automatically-generated data series colors. (0.0-1.0, default: - 1.0) | -
| colorValue | -0.5 |
- If colors is not specified, value of the data series colors, as in - hue/saturation/value. (0.0-1.0, default 0.5) | -
| clickCallback | -function(e,date){ alert(date); } |
- A function to call when a data point is clicked. The function should take - two arguments, the event object for the click and the date that was - clicked. (default null) | -
| zoomCallback | -function(minDate,maxDate) {} |
- A function to call when the zoom window is changed (either by zooming - in or out). minDate and maxDate are millis since epoch. | -
| strokeWidth | -2.0 |
- Width of the data lines. This can be used to increase the contrast or - some graphs. (default 1.0) | -
| dateWindow | -[Date.parse('2006-01-01'), |
- Initially zoom in on a section of the graph. Is of the form [earliest, - latest], where earliest/latest are millis since epoch. By default, the - full range of the input is shown. | -
| valueRange | -[10, 110] |
- Explicitly set the vertical range of the graph to [low, high]. By - default, some clever heuristics are used (see above). | -
| labelsSeparateLines | -true |
- Put <br/> between lines in the label string. Often used in - conjunction with labelsDiv. (default false) | -
| labelsDiv | -document.getElementById('foo') |
- Show data labels in an external div, rather than on the graph. (default - null) | -
| labelsKMB | -true |
- Show K/M/B for thousands/millions/billions on y-axis (default - false). | -
| labelsDivWidth | -250 | -Width (in pixels) of the div which shows information on the - currently-highlighted points. | -
| labelsDivStyles | -{} | -Additional styles to apply to the currently-highlighted points div. For - example, { 'font-weigth': 'bold' } will make the labels bold. | -
| highlightCircleSize | -3 |
- Size (in pixels) of the dot drawn over highlighted points (default 3). | -
| pixelsPerXLabel, pixelsPerYLabel | -50 | -Number of pixels to require between each x- and y-label. Larger values - will yield a sparser axis with fewer ticks. Defaults: 60 (x-axis), 30 - (y-axis). | -
| xAxisLabelWidth, yAxisLabelWidth | -50 | -Width (in pixels) of the x- and y-axis labels. | -
| axisLabelFontSize | -14 | -Size of the font (in pixels) to use in the axis labels, both x- and - y-axis. | -
| rightGap | -5 | -Number of pixels to leave blank at the right edge of the Dygraph. This - makes it easier to highlight the right-most data point. | -
| errorBars | -false |
- Does the data contain standard deviations? Setting this to true alters - the input format (see above). (default false) | -
| sigma | -2 | -When errorBars is set, shade this many standard deviations above/below - each point. | -
| fractions | -false | -When set, attempt to parse each cell in the CSV file as "a/b", where a - and b are integers. The ratio will be plotted. This allows computation of - Wilson confidence intervals (see below). | -
| wilsonInterval | -true | -Use in conjunction with the "fractions" option. Instead of plotting +/- - N standard deviations, dygraphs will compute a Wilson confidence interval - and plot that. This has more reasonable behavior for ratios close to 0 or - 1. | -
| customBars | -false | -When set, parse each CSV cell as "low;middle;high". Error bars will be - drawn for each point between low and high, with the series itself going - through middle. | -
Start by downloading dygraphs. Then read the Tutorial to learn how to use it, or just play with dygraphs on jsFiddle.
-Any options you specify also get passed on to PlotKit's Renderer class. dygraphs will override some of these (e.g. strokeColor), but others may be useful. The padding property is an example of this.
Once you've got your feet wet, look for inspiration in the demo gallery or check out our list of users.
-Here are a few problems that I've frequently run into while using the -dygraphs library.
+If you're using npm and a bundler like webpack, browserify or rollup, you can install dygraphs via:
-npm install --save dygraphs-
YYYYMMDD,series1,series2,.... And if you set the
- errorBars property, make sure you alternate data series and
- standard deviations.<center>
- tag. This applies to the CSS text-align property as well. If you
- want to center a Dygraph, put it inside a table with "align=center"
- set.import Dygraph from 'dygraphs';
+// or: const Dygraph = require('dygraphs');
+const g = new Dygraph(div, data, {});
- dateWindow property to a date. It expects
- milliseconds since epoch, which can be obtained from a JavaScript Date
- object's valueOf method.Check out the dygraphs ES6 sample project for more details on this approach.
+ -dygraphs is purely client-side JavaScript. It does not send your data to any -servers -- the data is processed entirely in the client's browser.
+Created May 9, 2008 by Dan Vanderkam
+ - - +