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@renecnielsen
Created January 20, 2016 07:37
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Inline Labels

This example shows how to implement Ann K. Emery’s technique of placings labels directly on top of a line in D3 4.0 Alpha.

To construct the multi-series line chart, the data is first transformed into separate arrays for each series. (The series names are automatically derived from the columns in the TSV file, thanks to a new dsv.parse feature.)

var series = data.columns.slice(1).map(function(key) {
  return data.map(function(d) {
    return {
      key: key,
      date: d.date,
      value: d[key]
    };
  });
});

A label is rendered for each point in each series. Beneath this label, a white rectangle is added, whose size and position is computed automatically using element.getBBox plus a little bit of padding. The resulting label is thus legible. The last label for each series gets an additional tspan to show the series name.

forked from mbostock's block: Inline Labels

date Apples Bananas
2009 130 40
2010 137 58
2011 166 97
2012 154 117
2013 179 98
2014 187 120
2015 189 84
<!DOCTYPE html>
<meta charset="utf-8">
<style>
text {
font: 10px sans-serif;
}
.axis path,
.axis line {
fill: none;
stroke: #000;
shape-rendering: crispEdges;
}
.line {
fill: none;
stroke-width: 1.5px;
}
.label {
text-anchor: middle;
}
.label rect {
fill: white;
}
.label-key {
font-weight: bold;
}
</style>
<svg width="960" height="500"></svg>
<script src="//d3js.org/d3.v4.0.0-alpha.4.min.js"></script>
<script>
var parseTime = d3.timeParse("%Y");
var svg = d3.select("svg");
var margin = {top: 30, right: 50, bottom: 30, left: 30},
width = +svg.attr("width") - margin.left - margin.right,
height = +svg.attr("height") - margin.top - margin.bottom,
labelPadding = 3;
var g = svg.append("g")
.attr("transform", "translate(" + margin.left + "," + margin.top + ")");
d3.requestTsv("data.tsv", function(d) {
d.date = parseTime(d.date);
for (var k in d) if (k !== "date") d[k] = +d[k];
return d;
}, function(error, data) {
if (error) throw error;
var series = data.columns.slice(1).map(function(key) {
return data.map(function(d) {
return {
key: key,
date: d.date,
value: d[key]
};
});
});
var x = d3.scaleTime()
.domain([data[0].date, data[data.length - 1].date])
.range([0, width]);
var y = d3.scaleLinear()
.domain([0, d3.max(series, function(s) { return d3.max(s, function(d) { return d.value; }); })])
.range([height, 0]);
var z = d3.scaleCategory10();
g.append("g")
.attr("class", "axis axis--x")
.attr("transform", "translate(0," + height + ")")
.call(d3.axisBottom().scale(x));
var serie = g.selectAll(".serie")
.data(series)
.enter().append("g")
.attr("class", "serie");
serie.append("path")
.attr("class", "line")
.style("stroke", function(d) { return z(d[0].key); })
.attr("d", d3.line()
.x(function(d) { return x(d.date); })
.y(function(d) { return y(d.value); }));
var label = serie.selectAll(".label")
.data(function(d) { return d; })
.enter().append("g")
.attr("class", "label")
.attr("transform", function(d, i) { return "translate(" + x(d.date) + "," + y(d.value) + ")"; });
label.append("text")
.attr("dy", ".35em")
.text(function(d) { return d.value; })
.filter(function(d, i) { return i === data.length - 1; })
.append("tspan")
.attr("class", "label-key")
.text(function(d) { return " " + d.key; });
label.append("rect", "text")
.datum(function() { return this.nextSibling.getBBox(); })
.attr("x", function(d) { return d.x - labelPadding; })
.attr("y", function(d) { return d.y - labelPadding; })
.attr("width", function(d) { return d.width + 2 * labelPadding; })
.attr("height", function(d) { return d.height + 2 * labelPadding; });
});
</script>
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