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Last active July 11, 2023 18:59
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Real-Time Line Chart
Raw
.block
license: mit
Raw
index.html
<!DOCTYPE html>
<html>
<head>
<title>Realtime Data Line Graph</title>
<meta name="viewport" content="initial-scale=1.0, user-scalable=no" />
<meta charset='utf-8' />
<script src="https://d3js.org/d3.v4.min.js"></script>
<style>
body {
font-family: "Helvetica Neue", Helvetica, Arial, sans-serif;
}
#chart {
max-width: 600px;
max-height: 400px;
}
</style>
</head>
<body>
<div id="chart"></div>
<script src="script.js"></script>
<script>
var lineArr = [];
var MAX_LENGTH = 100;
var duration = 500;
var chart = realTimeLineChart();
function randomNumberBounds(min, max) {
return Math.floor(Math.random() * max) + min;
}
function seedData() {
var now = new Date();
for (var i = 0; i < MAX_LENGTH; ++i) {
lineArr.push({
time: new Date(now.getTime() - ((MAX_LENGTH - i) * duration)),
x: randomNumberBounds(0, 5),
y: randomNumberBounds(0, 2.5),
z: randomNumberBounds(0, 10)
});
}
}
function updateData() {
var now = new Date();
var lineData = {
time: now,
x: randomNumberBounds(0, 5),
y: randomNumberBounds(0, 2.5),
z: randomNumberBounds(0, 10)
};
lineArr.push(lineData);
if (lineArr.length > 30) {
lineArr.shift();
}
d3.select("#chart").datum(lineArr).call(chart);
}
function resize() {
if (d3.select("#chart svg").empty()) {
return;
}
chart.width(+d3.select("#chart").style("width").replace(/(px)/g, ""));
d3.select("#chart").call(chart);
}
document.addEventListener("DOMContentLoaded", function() {
seedData();
window.setInterval(updateData, 500);
d3.select("#chart").datum(lineArr).call(chart);
d3.select(window).on('resize', resize);
});
</script>
</body>
</html>
Raw
script.js
function realTimeLineChart() {
var margin = {top: 20, right: 20, bottom: 20, left: 20},
width = 600,
height = 400,
duration = 500,
color = d3.schemeCategory10;
function chart(selection) {
// Based on https://bl.ocks.org/mbostock/3884955
selection.each(function(data) {
data = ["x", "y", "z"].map(function(c) {
return {
label: c,
values: data.map(function(d) {
return {time: +d.time, value: d[c]};
})
};
});
var t = d3.transition().duration(duration).ease(d3.easeLinear),
x = d3.scaleTime().rangeRound([0, width-margin.left-margin.right]),
y = d3.scaleLinear().rangeRound([height-margin.top-margin.bottom, 0]),
z = d3.scaleOrdinal(color);
var xMin = d3.min(data, function(c) { return d3.min(c.values, function(d) { return d.time; })});
var xMax = new Date(new Date(d3.max(data, function(c) {
return d3.max(c.values, function(d) { return d.time; })
})).getTime() - (duration*2));
x.domain([xMin, xMax]);
y.domain([
d3.min(data, function(c) { return d3.min(c.values, function(d) { return d.value; })}),
d3.max(data, function(c) { return d3.max(c.values, function(d) { return d.value; })})
]);
z.domain(data.map(function(c) { return c.label; }));
var line = d3.line()
.curve(d3.curveBasis)
.x(function(d) { return x(d.time); })
.y(function(d) { return y(d.value); });
var svg = d3.select(this).selectAll("svg").data([data]);
var gEnter = svg.enter().append("svg").append("g");
gEnter.append("g").attr("class", "axis x");
gEnter.append("g").attr("class", "axis y");
gEnter.append("defs").append("clipPath")
.attr("id", "clip")
.append("rect")
.attr("width", width-margin.left-margin.right)
.attr("height", height-margin.top-margin.bottom);
gEnter.append("g")
.attr("class", "lines")
.attr("clip-path", "url(#clip)")
.selectAll(".data").data(data).enter()
.append("path")
.attr("class", "data");
var legendEnter = gEnter.append("g")
.attr("class", "legend")
.attr("transform", "translate(" + (width-margin.right-margin.left-75) + ",25)");
legendEnter.append("rect")
.attr("width", 50)
.attr("height", 75)
.attr("fill", "#ffffff")
.attr("fill-opacity", 0.7);
legendEnter.selectAll("text")
.data(data).enter()
.append("text")
.attr("y", function(d, i) { return (i*20) + 25; })
.attr("x", 5)
.attr("fill", function(d) { return z(d.label); });
var svg = selection.select("svg");
svg.attr('width', width).attr('height', height);
var g = svg.select("g")
.attr("transform", "translate(" + margin.left + "," + margin.top + ")");
g.select("g.axis.x")
.attr("transform", "translate(0," + (height-margin.bottom-margin.top) + ")")
.transition(t)
.call(d3.axisBottom(x).ticks(5));
g.select("g.axis.y")
.transition(t)
.attr("class", "axis y")
.call(d3.axisLeft(y));
g.select("defs clipPath rect")
.transition(t)
.attr("width", width-margin.left-margin.right)
.attr("height", height-margin.top-margin.right);
g.selectAll("g path.data")
.data(data)
.style("stroke", function(d) { return z(d.label); })
.style("stroke-width", 1)
.style("fill", "none")
.transition()
.duration(duration)
.ease(d3.easeLinear)
.on("start", tick);
g.selectAll("g .legend text")
.data(data)
.text(function(d) {
return d.label.toUpperCase() + ": " + d.values[d.values.length-1].value;
});
// For transitions https://bl.ocks.org/mbostock/1642874
function tick() {
d3.select(this)
.attr("d", function(d) { return line(d.values); })
.attr("transform", null);
var xMinLess = new Date(new Date(xMin).getTime() - duration);
d3.active(this)
.attr("transform", "translate(" + x(xMinLess) + ",0)")
.transition()
.on("start", tick);
}
});
}
chart.margin = function(_) {
if (!arguments.length) return margin;
margin = _;
return chart;
};
chart.width = function(_) {
if (!arguments.length) return width;
width = _;
return chart;
};
chart.height = function(_) {
if (!arguments.length) return height;
height = _;
return chart;
};
chart.color = function(_) {
if (!arguments.length) return color;
color = _;
return chart;
};
chart.duration = function(_) {
if (!arguments.length) return duration;
duration = _;
return chart;
};
return chart;
}
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