npm package: @nwaltham/venn.js
Description: Area Proportional Venn and Euler Diagrams
Author: Ben Frederickson
Latest version: 0.2.1-4.3

venn.js [![Build Status](https://travis-ci.org/benfred/venn.js.svg?branch=master)](https://travis-ci.org/benfred/venn.js)
=======

A javascript library for laying out area proportional venn and euler diagrams.

Details of how this library works can be found on the [blog 
post](http://www.benfrederickson.com/venn-diagrams-with-d3.js/)
I wrote about this. A follow up post [discusses testing strategy and
algorithmic improvements](http://www.benfrederickson.com/better-venn-diagrams/).


### Installing

If you use NPM, `npm install venn.js`. Otherwise, download the [latest release](https://github.com/benfred/venn.js/releases/latest).


### Usage

This library depends on [d3.js](http://d3js.org/) to display the venn
diagrams.


##### Simple layout

To lay out a simple diagram, just define the sets and their sizes along with the sizes 
of all the set intersections.

The VennDiagram object will calculate a layout that is proportional to the
input sizes, and display it in the appropriate selection when called:

```javascript
var sets = [ {sets: ['A'], size: 12}, 
             {sets: ['B'], size: 12},
             {sets: ['A','B'], size: 2}];

var chart = venn.VennDiagram()
d3.select("#venn").datum(sets).call(chart);
```

[View this example ](http://benfred.github.io/venn.js/examples/simple.html)

##### Changing the Style

The style of the Venn Diagram can be customized by using D3 after the diagram
has been drawn. For instance to draw a Venn Diagram with white text and a darker fill:

```javascript
var chart = venn.VennDiagram()
d3.select("#inverted").datum(sets).call(chart)
            
d3.selectAll("#inverted .venn-circle path")
    .style("fill-opacity", .8);

d3.selectAll("#inverted text").style("fill", "white");
```

[View this example, along with other possible styles](http://benfred.github.io/venn.js/examples/styled.html)


##### Dynamic layout

To have a layout that reacts to a change in input, all that you need to do is
update the dataset and call the chart again:

```javascript
// draw the initial diagram
var chart = venn.VennDiagram()
d3.select("#venn").datum(getSetIntersections()).call(chart);

// redraw the diagram on any change in input
d3.selectAll("input").on("change", function() {
    d3.select("#venn").datum(getSetIntersections()).call(chart);
});
```

[View this example](http://benfred.github.io/venn.js/examples/dynamic.html)

##### Making the diagram interactive

Making the diagram interactive is basically the same idea as changing the style: just add event listeners to the elements in the venn diagram. To change the text size and circle colours on mouseover:

```javascript
d3.selectAll("#rings .venn-circle")
    .on("mouseover", function(d, i) {
        var node = d3.select(this).transition();
        node.select("path").style("fill-opacity", .2);
        node.select("text").style("font-weight", "100")
                           .style("font-size", "36px");
    })
    .on("mouseout", function(d, i) {
        var node = d3.select(this).transition();
        node.select("path").style("fill-opacity", 0);
        node.select("text").style("font-weight", "100")
                           .style("font-size", "24px");
    });
```
[View this example](http://benfred.github.io/venn.js/examples/interactive.html)

##### Adding tooltips

Another common case is adding a tooltip when hovering over the elements in the diagram. The only
tricky thing here is maintaining the correct Z-order so that the smallest intersection areas
are on top, while still making the area that is being hovered over appear on top of the others:

```javascript
// draw venn diagram
var div = d3.select("#venn")
div.datum(sets).call(venn.VennDiagram());

// add a tooltip
var tooltip = d3.select("body").append("div")
    .attr("class", "venntooltip");

// add listeners to all the groups to display tooltip on mouseover
div.selectAll("g")
    .on("mouseover", function(d, i) {
        // sort all the areas relative to the current item
        venn.sortAreas(div, d);

        // Display a tooltip with the current size
        tooltip.transition().duration(400).style("opacity", .9);
        tooltip.text(d.size + " users");
        
        // highlight the current path
        var selection = d3.select(this).transition("tooltip").duration(400);
        selection.select("path")
            .style("stroke-width", 3)
            .style("fill-opacity", d.sets.length == 1 ? .4 : .1)
            .style("stroke-opacity", 1);
    })

    .on("mousemove", function() {
        tooltip.style("left", (d3.event.pageX) + "px")
               .style("top", (d3.event.pageY - 28) + "px");
    })
    
    .on("mouseout", function(d, i) {
        tooltip.transition().duration(400).style("opacity", 0);
        var selection = d3.select(this).transition("tooltip").duration(400);
        selection.select("path")
            .style("stroke-width", 0)
            .style("fill-opacity", d.sets.length == 1 ? .25 : .0)
            .style("stroke-opacity", 0);
    });
```
[View this example](http://benfred.github.io/venn.js/examples/intersection_tooltip.html)

Released under the MIT License.