Sankey diagram in javascript

StackOverflow https://stackoverflow.com/questions/4545254

Question

I want to draw a Sankey diagram using Javascript. Can anyone provide some direction regarding the algorithms or libraries that are available for this?

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Solution

This is a basic Sankey diagram using raphaeljs

function Sankey(x0, y0, height, losses) {
    var initialcolor = Raphael.getColor();
    var start = x0 + 200;
    var level = y0 + height;
    var heightunit = height / 100;
    var remaining = 100 * heightunit;

    function drawloss(start, level, loss) {
        var thecolor = Raphael.getColor();
        paper.path("M" + (start - 100) + "," + (level - loss) + "L" + start + "," + (level - loss)).attr({stroke: thecolor});
        paper.path("M" + (start - 100) + "," + level + "L" + start + "," + level).attr({stroke: thecolor});
        paper.path("M " + start + "," + level + " Q" + (start + 100) + "," + level + " " + (start + 100) + "," + (level + 100)).attr({stroke: thecolor});
        paper.path("M " + start + "," + (level - loss) + " Q" + (start + 100 + loss) + "," + (level - loss) + " " + (start + 100 + loss) + "," + (level + 100)).attr({stroke: thecolor});
        paper.path("M " + (start + 100) + "," + (level + 100) + " L " + (start - 10 + 100) + "," + (level + 100) + " L " + (start + loss / 2 + 100) + "," + (level + 110) + " L " + (start + loss + 10 + 100) + "," + (level + 100) + " L " + (start + loss + 100) + ", " + (level + 100)).attr({stroke: thecolor});
    }

    function drawremaining(start, level, loss) {
        paper.path("M 100," + y0 + "L" + (start + 100) + "," + y0).attr({stroke: initialcolor});
        paper.path("M" + (start - 100) + "," + level + "L" + (start + 100) + "," + level).attr({stroke: initialcolor});
        paper.path("M " + (start + 100) + " " + y0 + " L " + (start + 100) + " " + (y0 - 10) + " L " + (start + 110) + " " + (y0 + loss / 2) + " L " + (start + 100) + " " + (level + 10) + " L " + (start + 100) + " " + level).attr({stroke: initialcolor});
    }

    function drawstart(x0, y0, width, height) {
        paper.path("M " + x0 + "," + y0 + "L" + (x0 + width) + "," + y0).attr({stroke: initialcolor});
        paper.path("M " + x0 + "," + (y0 + height) + "L" + (x0 + width) + "," + y0 + height)).attr({stroke:  initialcolor});
        paper.path("M " + x0 + "," + y0 + "L" + x0 + "," + (y0 + height)).attr({stroke: initialcolor});
    }

    drawstart(x0, y0, 100, height);

    for (var i in losses) {
        drawloss(start, level, losses[i] * heightunit);
        remaining -= losses[i] * heightunit;
        level -= losses[i] * heightunit;
        start += 100;
    }
}

And I use it like this:

<div id="notepad" style="height:1000px; width:1000px; background: #eee"></div>
<script type="text/javascript">
    var paper = Raphael(document.getElementById("notepad"), 1020, 1000);
    var losses=[50, 30, 5];
    Sankey(10, 100, 200, losses);
</script>

OTHER TIPS

In case helpful to others: I've extracted my javascript sankey diagram drawing code here:

http://tamc.github.com/Sankey/

The original usage is on this UK government site:

http://2050-calculator-tool.decc.gov.uk/pathways/2022222122222103332220023211022330220130233022012/sankey

D3.js uses a plugin to create sankey diagrams pretty well.

http://bost.ocks.org/mike/sankey/

Here is a fairly detailed explanation of how Mike Bostock's D3-based Sankey DIagram code works: http://www.d3noob.org/2013/02/sankey-diagrams-description-of-d3js-code.html

I have implemented this on a Grails-based app server and it works.

Google Charts includes the Sankey Diagram: https://developers.google.com/chart/interactive/docs/gallery/sankey

Thanks to zenify for starting me on the path, I had to rejig some of the copied code above to get it to work but it definitely gives a good starting point. The code below can be copied into a .htm file and you just need to have raphael-min.js in the same directory for it to work.

Regards / Colm

<!DOCTYPE HTML PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" class="JS">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"/>
<title>Raphael makes Sankey</title>
<script type="text/javascript" src="raphael-min.js"></script>
<script type="text/javascript">
function Sankey(x0,y0,height,losses){
    initialcolor= Raphael.getColor();
    var start=x0+200;
    var level=y0+height;    
    var heightunit=height/100;
    var remaining=100*heightunit;

function drawloss(start,level,loss){
    var thecolor=Raphael.getColor();
    paper.path("M"+(start-100)+","+(level-loss)+"L"+start+","+(level-loss)).attr({stroke: thecolor});
    paper.path("M"+(start-100)+","+(level)+"L"+start+","+(level)).attr({stroke: thecolor});
    paper.path("M "+start+","+level+" Q"+(start+100)+","+level+" "+(start+100)+","+(level+100)).attr({stroke: thecolor});
    paper.path("M "+start+","+(level-loss)+" Q"+(start+100+loss)+","+(level-loss)+" "+(start+100+loss)+","+(level+100)).attr({stroke: thecolor});
    paper.path("M "+(start+100)+","+(level+100)+" L "+(start-10+100)+","+(level+100)+" L "+(start+(loss/2)+100)+","+(level+110)+" L "+(start+(loss)+10+100)+","+(level+100)+" L "+(start+(loss)+100)+", "+(level+100)).attr({stroke: thecolor});
}

function drawremaining(start,level,loss){
    paper.path("M 100,"+y0+"L"+(start+100)+","+y0).attr({stroke: initialcolor});
    paper.path("M"+(start-100)+","+(level)+"L"+(start+100)+","+(level)).attr({stroke: initialcolor});
    paper.path("M "+(start+100)+" "+y0+" L "+(start+100)+" "+(y0-10)+" L "+(start+110)+" "+(y0+(loss/2))+" L "+(start+100)+" "+(level+10)+" L "+(start+100)+" "+(level)).attr({stroke: initialcolor});
}

function drawstart(x0, y0, width, height){
    paper.path("M "+x0+","+y0+"L"+(x0+width)+","+y0+"").attr({stroke: initialcolor});
    paper.path("M "+x0+","+(y0+height)+"L"+(x0+width)+","+y0+height+"").attr({stroke:  initialcolor});
    paper.path("M "+x0+","+y0+"L"+x0+","+(y0+height)+"").attr({stroke: initialcolor});
}

    drawstart(x0,y0,100,height);
    for (var i in losses){
      drawloss(start,level,losses[i]*heightunit);
      remaining-=losses[i]*heightunit;
      level-=losses[i]*heightunit;
      start+=100;
    }
    drawremaining(start, level, remaining);
}
</script>
</head>
<body id="blog">
    <div id="notepad" style="height:1000px; width:1000px; background: #eee"></div>
    <script type="text/javascript">
    var paper = Raphael(document.getElementById("notepad"), 1020, 1000);
    var losses=[50, 30, 5];
    Sankey(10, 100, 200, losses);
    </script>
</body>
</html>
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