I have been playing with D3.js and I am trying to make a Streaming

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Asked: June 4, 20262026-06-04T06:31:16+00:00 2026-06-04T06:31:16+00:00

I have been playing with D3.js and I am trying to make a Streaming

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I have been playing with D3.js and I am trying to make a Streaming Graph visualization using real-time data.

I did study very much this article
http://bost.ocks.org/mike/path/

I also read this question and answers
Svg clip-path within rectangle does not work
but this is for a line. I do have a d3.svg.area object

Then I read this article
D3 Real-Time streamgraph (Graph Data Visualization)
but still couldn’t find any answers

My two questions:

when drawing a streaming graph, i noticed graph is always set at the bottom. Each refresh a calculating function found the maximum of data and set the bottom of the graph at the bottom of the element where you draw your graph.

var area = d3.svg.area()
   .x(function(data) { return data.x * width / Xmaximum; })
   .y0(function(data) { return height - data.y0 * height / Ymaximum; })
   .y1(function(data) { return height - (data.y + data.y0) * height / Ymaximum; });

How can i do to let the graph in the middle of the axis?
i guess i have to play around with the x, y0 and y1 of area but how exactly?

if you try my code a part of the graph is shown at the left.
i know there is something wrong with:

vis.append("defs").append("clipPath")
   .attr("id", "clip")
  .append("rect")
   .attr("width", width)
   .attr("height", height);

 vis.append("g")
   .attr("clip-path", "url(#clip)");

i search for any response in others topics and all around the web but I am keep stuck here!

Here is my code:

<!DOCTYPE html>
<html>
<head>
    <title>Test visu</title>
    <style>
        .line {
            fill: none;
            stroke: #000;
            stroke-width: 1.5px;
        }
        .axis path, .axis line {
            margin-left: 30px;
            fill: none;
            stroke: #000;
            shape-rendering: crispEdges;
        }
        svg {
            font: 10px sans-serif;
        }

        #restart{
            visibility: hidden;
        }

        #visu{
            margin-left: 70px;
            //border: 5px solid black;
            width: 900px;
            height: 500px;
        }

    </style>
</head>

<body>
    <div id="visu">
        <script src="http://mbostock.github.com/d3/d3.js?2.7.2"></script>
            var CONS = 100;

            var layers_number = 4;
            var samples_number = 50;

            var margin = {top: 6, right: 0, bottom: 6, left: 40};
            var width = 900 - margin.right;
            var height = 500 - margin.top - margin.bottom;

            var Xmaximum = samples_number - 1;
            var Ymaximum = CONS * layers_number;

            var initial_table = new Array();

            for (var i = 0 ; i < layers_number ; ++i){
                initial_table[i] = new Array();
                for (var j = 0 ; j < samples_number ; ++j){
                    initial_table[i][j] = randomNber();
                }
            }

            var values = new Array();
            for (var i = 0 ; i < layers_number ; ++i)
                values[i] = new Array();

            var data0 = d3.layout.stack().offset("wiggle")(init_layers(layers_number,samples_number));

            function color (indice){
                if (indice == 0)
                    return "green";
                else if (indice == 1)
                    return "blue";
                else if (indice == 2)
                    return "red";
                else if (indice == 3)
                    return "black";
                return "black";
            }

            var y = d3.scale.linear()
                              .domain([0, Ymaximum])
                              .range([height, 0]);

            var area = d3.svg.area()
                .x(function(data) { return data.x * width / Xmaximum; })
                .y0(function(data) { return height - data.y0 * height / Ymaximum; })
                .y1(function(data) { return height - (data.y + data.y0) * height / Ymaximum; });

            var vis = d3.select("div")
                .append("svg")
                  .style("margin-left", -margin.left + "px")
                .attr("width", width + margin.left + margin.right)
                .attr("height", height + margin.top + margin.bottom)
                .append("g")
                  .attr("transform", "translate(" + margin.left + "," + margin.top + ")");

            vis.append("defs").append("clipPath")
                  .attr("id", "clip")
                .append("rect")
                  .attr("width", width)
                  .attr("height", height);

            vis.append("g")
                .attr("clip-path", "url(#clip)");

            vis.selectAll("path")
                .data(data0)
                .enter()
                .append("path")
                .style("fill", function(data, indice) { return color(indice); })
                .attr("d", area);

            vis.append("g")
                .attr("class", "y axis")
                  .call(d3.svg.axis().scale(y).ticks(5).orient("left"));

            transition();

            function transition() {
                data0 = d3.layout.stack().offset("wiggle")(update_layers(layers_number,samples_number));

                vis.selectAll("path")
                    .data(data0)
                    .attr("d", area)
                    .attr("transform", null)
                    .transition()
                    .duration(860)
                    .ease("linear")
                    .attr("transform", "translate(" + -(width / samples_number) + ")")
                    .each("end", function (data,indice) {
                        if (indice==0) transition();
                    });

                for (var i = 0 ; i < values.length ; ++i)
                    values[i].shift();
            }

            function init_layers(layers_number, samples_number) {
                return d3.range(layers_number).map(function(data,indice) {
                    for (var i = 0 ; i < samples_number ; i++)
                        values[indice][i] = initial_table[indice][i];
                    return values[indice].map(stream_index);
                });
            }

            function update_layers(layers_number, samples_number) {
                return d3.range(layers_number).map(function(data,indice) {
                    values[indice][samples_number] = randomNber();
                    return values[indice].map(stream_index);
                });
            }

            function stream_index(data, indice) {
                return {x: indice, y: Math.max(0, data)};
            }

            function randomNber(){
                return parseInt(Math.random()*100)+1;
            }   

    </div>
</body>
</html>