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Jul 3, 2018
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D3 Real Time Chart with Multiple Data Streams
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chart={
//'use strict';
// create the real time chart
var chart = realTimeChartMulti()
.title("Chart Title")
.yTitle("Categories")
.xTitle("Time")
.yDomain(["Category1"]) // initial y domain (note array)
.border(true)
.width(900)
.height(350);
// invoke the chart
var chartDiv = d3.select("#viewDiv").append("div")
.attr("id", "chartDiv")
.call(chart);
// alternative and equivalent invocation
//chart(chartDiv);
// event handler for debug checkbox
d3.select("#debug").on("change", function() {
var state = d3.select(this).property("checked")
chart.debug(state);
})
// event handler for halt checkbox
d3.select("#halt").on("change", function() {
var state = d3.select(this).property("checked")
chart.halt(state);
})
// configure the data generator
// mean and deviation for generation of time intervals
var tX = 5; // time constant, multiple of one second
var meanMs = 1000 * tX, // milliseconds
dev = 200 * tX; // std dev
// define time scale
var timeScale = d3.scale.linear()
.domain([300 * tX, 1700 * tX])
.range([300 * tX, 1700 * tX])
.clamp(true);
// define function that returns normally distributed random numbers
var normal = d3.random.normal(meanMs, dev);
// define color scale
var color = d3.scale.category10();
// in a normal use case, real time data would arrive through the network or some other mechanism
var d = -1;
var shapes = ["rect", "circle"];
var timeout = 0;
// define data generator
function dataGenerator() {
setTimeout(function() {
// add categories dynamically
d++;
switch (d) {
case 5:
chart.yDomain(["Category1", "Category2"]);
break;
case 10:
chart.yDomain(["Category1", "Category2", "Category3"]);
break;
default:
}
// output a sample for each category, each interval (five seconds)
chart.yDomain().forEach(function(cat, i) {
// create randomized timestamp for this category data item
var now = new Date(new Date().getTime() + i * (Math.random() - 0.5) * 1000);
// create new data item
var obj;
var doSimple = false;
if (doSimple) {
obj = {
// simple data item (simple black circle of constant size)
time: now,
color: "black",
opacity: 1,
category: "Category" + (i + 1),
type: "circle",
size: 5,
};
} else {
obj = {
// complex data item; four attributes (type, color, opacity and size) are changing dynamically with each iteration (as an example)
time: now,
color: color(d % 10),
opacity: Math.max(Math.random(), 0.3),
category: "Category" + (i + 1),
//type: shapes[Math.round(Math.random() * (shapes.length - 1))], // the module currently doesn't support dynamically changed svg types (need to add key function to data, or method to dynamically replace svg object – tbd)
type: "circle",
size: Math.max(Math.round(Math.random() * 12), 4),
};
}
// send the datum to the chart
chart.datum(obj);
});
// drive data into the chart at average interval of five seconds
// here, set the timeout to roughly five seconds
timeout = Math.round(timeScale(normal()));
// do forever
dataGenerator();
}, timeout);
}
// start the data generator
dataGenerator();
}
<!-- Author: Bo Ericsson, bo@boe.net -->
<!-- Inspiration from numerous examples by Mike Bostock, http://bl.ocks.org/mbostock, -->
<!-- and example by Andy Aiken, http://blog.scottlogic.com/2014/09/19/interactive.html -->
//'use strict';
function realTimeChartMulti() {
var version = "0.1.0",
datum, data,
maxSeconds = 300, pixelsPerSecond = 10,
svgWidth = 700, svgHeight = 300,
margin = { top: 20, bottom: 20, left: 100, right: 30, topNav: 10, bottomNav: 20 },
dimension = { chartTitle: 20, xAxis: 20, yAxis: 20, xTitle: 20, yTitle: 20, navChart: 70 },
maxY = 100, minY = 0,
chartTitle, yTitle, xTitle,
drawXAxis = true, drawYAxis = true, drawNavChart = true,
border,
selection,
barId = 0,
yDomain = [],
debug = false,
barWidth = 5,
halted = false,
x, y,
xNav, yNav,
width, height,
widthNav, heightNav,
xAxisG, yAxisG,
xAxis, yAxis,
svg;
// create the chart
var chart = function(s) {
selection = s;
if (selection == undefined) {
console.error("selection is undefined");
return;
};
// process titles
chartTitle = chartTitle || "";
xTitle = xTitle || "";
yTitle = yTitle || "";
// compute component dimensions
var chartTitleDim = chartTitle == "" ? 0 : dimension.chartTitle,
xTitleDim = xTitle == "" ? 0 : dimension.xTitle,
yTitleDim = yTitle == "" ? 0 : dimension.yTitle,
xAxisDim = !drawXAxis ? 0 : dimension.xAxis,
yAxisDim = !drawYAxis ? 0 : dimension.yAxis,
navChartDim = !drawNavChart ? 0 : dimension.navChart;
// compute dimension of main and nav charts, and offsets
var marginTop = margin.top + chartTitleDim;
height = svgHeight - marginTop - margin.bottom - chartTitleDim - xTitleDim - xAxisDim - navChartDim + 30;
heightNav = navChartDim - margin.topNav - margin.bottomNav;
var marginTopNav = svgHeight - margin.bottom - heightNav - margin.topNav;
width = svgWidth - margin.left - margin.right;
widthNav = width;
// append the svg
svg = selection.append("svg")
.attr("width", svgWidth)
.attr("height", svgHeight)
.style("border", function(d) {
if (border) return "1px solid lightgray";
else return null;
});
// create main group and translate
var main = svg.append("g")
.attr("transform", "translate (" + margin.left + "," + marginTop + ")");
// define clip-path
main.append("defs").append("clipPath")
.attr("id", "myClip")
.append("rect")
.attr("x", 0)
.attr("y", 0)
.attr("width", width)
.attr("height", height);
// create chart background
main.append("rect")
.attr("x", 0)
.attr("y", 0)
.attr("width", width)
.attr("height", height)
.style("fill", "#f5f5f5");
// note that two groups are created here, the latter assigned to barG;
// the former will contain a clip path to constrain objects to the chart area;
// no equivalent clip path is created for the nav chart as the data itself
// is clipped to the full time domain
var barG = main.append("g")
.attr("class", "barGroup")
.attr("transform", "translate(0, 0)")
.attr("clip-path", "url(#myClip")
.append("g");
// add group for x axis
xAxisG = main.append("g")
.attr("class", "x axis")
.attr("transform", "translate(0," + height + ")");
// add group for y axis
yAxisG = main.append("g")
.attr("class", "y axis");
// in x axis group, add x axis title
xAxisG.append("text")
.attr("class", "title")
.attr("x", width / 2)
.attr("y", 25)
.attr("dy", ".71em")
.text(function(d) {
var text = xTitle == undefined ? "" : xTitle;
return text;
});
// in y axis group, add y axis title
yAxisG.append("text")
.attr("class", "title")
.attr("transform", "rotate(-90)")
.attr("x", - height / 2)
.attr("y", -margin.left + 15) //-35
.attr("dy", ".71em")
.text(function(d) {
var text = yTitle == undefined ? "" : yTitle;
return text;
});
// in main group, add chart title
main.append("text")
.attr("class", "chartTitle")
.attr("x", width / 2)
.attr("y", -20)
.attr("dy", ".71em")
.text(function(d) {
var text = chartTitle == undefined ? "" : chartTitle;
return text;
});
// define main chart scales
x = d3.time.scale().range([0, width]);
y = d3.scale.ordinal().domain(yDomain).rangeRoundPoints([height, 0], 1)
// define main chart axis
xAxis = d3.svg.axis().orient("bottom");
yAxis = d3.svg.axis().orient("left");
// add nav chart
var nav = svg.append("g")
.attr("transform", "translate (" + margin.left + "," + marginTopNav + ")");
// add nav background
nav.append("rect")
.attr("x", 0)
.attr("y", 0)
.attr("width", width)
.attr("height", heightNav)
.style("fill", "#F5F5F5")
.style("shape-rendering", "crispEdges")
.attr("transform", "translate(0, 0)");
// add group to data items
var navG = nav.append("g")
.attr("class", "nav");
// add group to hold nav x axis
// please note that a clip path has yet to be added here (tbd)
var xAxisGNav = nav.append("g")
.attr("class", "x axis")
.attr("transform", "translate(0," + heightNav + ")");
// define nav chart scales
xNav = d3.time.scale().range([0, widthNav]);
yNav = d3.scale.ordinal().domain(yDomain).rangeRoundPoints([heightNav, 0], 1)
// define nav axis
var xAxisNav = d3.svg.axis().orient("bottom");
// compute initial time domains...
var ts = new Date().getTime();
// first, the full time domain
var endTime = new Date(ts);
var startTime = new Date(endTime.getTime() - maxSeconds * 1000);
var interval = endTime.getTime() - startTime.getTime();
// then the viewport time domain (what's visible in the main chart and the viewport in the nav chart)
var endTimeViewport = new Date(ts);
var startTimeViewport = new Date(endTime.getTime() - width / pixelsPerSecond * 1000);
var intervalViewport = endTimeViewport.getTime() - startTimeViewport.getTime();
var offsetViewport = startTimeViewport.getTime() - startTime.getTime();
// set the scale domains for main and nav charts
x.domain([startTimeViewport, endTimeViewport]);
xNav.domain([startTime, endTime]);
// update axis with modified scale
xAxis.scale(x)(xAxisG);
yAxis.scale(y)(yAxisG);
xAxisNav.scale(xNav)(xAxisGNav);
// create brush (moveable, changable rectangle that determines the time domain of main chart)
var viewport = d3.svg.brush()
.x(xNav)
.extent([startTimeViewport, endTimeViewport])
.on("brush", function () {
// get the current time extent of viewport
var extent = viewport.extent();
startTimeViewport = extent[0];
endTimeViewport = extent[1];
// compute viewport extent in milliseconds
intervalViewport = endTimeViewport.getTime() - startTimeViewport.getTime();
offsetViewport = startTimeViewport.getTime() - startTime.getTime();
// handle invisible viewport
if (intervalViewport == 0) {
intervalViewport = maxSeconds * 1000;
offsetViewport = 0;
}
// update the x domain of the main chart
x.domain(viewport.empty() ? xNav.domain() : extent);
// update the x axis of the main chart
xAxis.scale(x)(xAxisG);
// update display
refresh();
});
// create group and assign to brush
var viewportG = nav.append("g")
.attr("class", "viewport")
.call(viewport)
.selectAll("rect")
.attr("height", heightNav);
// initial invocation; update display
data = [];
refresh();
// function to refresh the viz upon changes of the time domain
// (which happens constantly), or after arrival of new data, or at init
function refresh() {
// process data to remove too late data items
data = data.filter(function(d) {
if (d.time.getTime() > startTime.getTime()) return true;
})
// determine number of categories
var categoryCount = yDomain.length;
if (debug) console.log("yDomain", yDomain)
// here we bind the new data to the main chart
// note: no key function is used here; therefore the data binding is
// by index, which effectivly means that available DOM elements
// are associated with each item in the available data array, from
// first to last index; if the new data array contains fewer elements
// than the existing DOM elements, the LAST DOM elements are removed;
// basically, for each step, the data items "walks" leftward (each data
// item occupying the next DOM element to the left);
// This data binding is very different from one that is done with a key
// function; in such a case, a data item stays "resident" in the DOM
// element, and such DOM element (with data) would be moved left, until
// the x position is to the left of the chart, where the item would be
// exited
var updateSel = barG.selectAll(".bar")
.data(data);
// remove items
updateSel.exit().remove();
// add items
updateSel.enter()
.append(function(d) {
if (debug) { console.log("d", JSON.stringify(d)); }
if (d.type == undefined) console.error(JSON.stringify(d))
var type = d.type || "circle";
var node = document.createElementNS("http://www.w3.org/2000/svg", type);
return node;
})
.attr("class", "bar")
.attr("id", function() {
return "bar-" + barId++;
});
// update items; added items are now part of the update selection
updateSel
.attr("x", function(d) {
var retVal = null;
switch (getTagName(this)) {
case "rect":
var size = d.size || 6;
retVal = Math.round(x(d.time) - size / 2);
break;
default:
}
return retVal;
})
.attr("y", function(d) {
var retVal = null;
switch (getTagName(this)) {
case "rect":
var size = d.size || 6;
retVal = y(d.category) - size / 2;
break;
default:
}
return retVal;
})
.attr("cx", function(d) {
var retVal = null;
switch (getTagName(this)) {
case "circle":
retVal = Math.round(x(d.time));
break;
default:
}
return retVal;
})
.attr("cy", function(d) {
var retVal = null;
switch (getTagName(this)) {
case "circle":
retVal = y(d.category);
break;
default:
}
return retVal;
})
.attr("r", function(d) {
var retVal = null;
switch (getTagName(this)) {
case "circle":
retVal = d.size / 2;
break;
default:
}
return retVal;
})
.attr("width", function(d) {
var retVal = null;
switch (getTagName(this)) {
case "rect":
retVal = d.size;
break;
default:
}
return retVal;
})
.attr("height", function(d) {
var retVal = null;
switch (getTagName(this)) {
case "rect":
retVal = d.size;
break;
default:
}
return retVal;
})
.style("fill", function(d) { return d.color || "black"; })
//.style("stroke", "orange")
//.style("stroke-width", "1px")
//.style("stroke-opacity", 0.8)
.style("fill-opacity", function(d) { return d.opacity || 1; });
// create update selection for the nav chart, by applying data
var updateSelNav = navG.selectAll("circle")
.data(data);
// remove items
updateSelNav.exit().remove();
// add items
updateSelNav.enter().append("circle")
.attr("r", 1)
.attr("fill", "black")
// added items now part of update selection; set coordinates of points
updateSelNav
.attr("cx", function(d) {
return Math.round(xNav(d.time));
})
.attr("cy", function(d) {
return yNav(d.category);
})
} // end refreshChart function
function getTagName(that) {
var tagName = d3.select(that).node().tagName;
return (tagName);
}
// function to keep the chart "moving" through time (right to left)
setInterval(function() {
if (halted) return;
// get current viewport extent
var extent = viewport.empty() ? xNav.domain() : viewport.extent();
var interval = extent[1].getTime() - extent[0].getTime();
var offset = extent[0].getTime() - xNav.domain()[0].getTime();
// compute new nav extents
endTime = new Date();
startTime = new Date(endTime.getTime() - maxSeconds * 1000);
// compute new viewport extents
startTimeViewport = new Date(startTime.getTime() + offset);
endTimeViewport = new Date(startTimeViewport.getTime() + interval);
viewport.extent([startTimeViewport, endTimeViewport])
// update scales
x.domain([startTimeViewport, endTimeViewport]);
xNav.domain([startTime, endTime]);
// update axis
xAxis.scale(x)(xAxisG);
xAxisNav.scale(xNav)(xAxisGNav);
// refresh svg
refresh();
}, 200)
// end setInterval function
return chart;
} // end chart function
// chart getters/setters
// new data item (this most recent item will appear
// on the right side of the chart, and begin moving left)
chart.datum = function(_) {
if (arguments.length == 0) return datum;
datum = _;
data.push(datum);
return chart;
}
// svg width
chart.width = function(_) {
if (arguments.length == 0) return svgWidth;
svgWidth = _;
return chart;
}
// svg height
chart.height = function(_) {
if (arguments.length == 0) return svgHeight;
svgHeight = _;
return chart;
}
// svg border
chart.border = function(_) {
if (arguments.length == 0) return border;
border = _;
return chart;
}
// chart title
chart.title = function(_) {
if (arguments.length == 0) return chartTitle;
chartTitle = _;
return chart;
}
// x axis title
chart.xTitle = function(_) {
if (arguments.length == 0) return xTitle;
xTitle = _;
return chart;
}
// y axis title
chart.yTitle = function(_) {
if (arguments.length == 0) return yTitle;
yTitle = _;
return chart;
}
// yItems (can be dynamically added after chart construction)
chart.yDomain = function(_) {
if (arguments.length == 0) return yDomain;
yDomain = _;
if (svg) {
// update the y ordinal scale
y = d3.scale.ordinal().domain(yDomain).rangeRoundPoints([height, 0], 1);
// update the y axis
yAxis.scale(y)(yAxisG);
// update the y ordinal scale for the nav chart
yNav = d3.scale.ordinal().domain(yDomain).rangeRoundPoints([heightNav, 0], 1);
}
return chart;
}
// debug
chart.debug = function(_) {
if (arguments.length == 0) return debug;
debug = _;
return chart;
}
// halt
chart.halt = function(_) {
if (arguments.length == 0) return halted;
halted = _;
return chart;
}
// version
chart.version = version;
return chart;
} // end realTimeChart function
Purpose-built for displays of data
Observable is your go-to platform for exploring data and creating expressive data visualizations. Use reactive JavaScript notebooks for prototyping and a collaborative canvas for visual data exploration and dashboard creation.
