d3js stack chart: how to add text on each layer? - d3.js

Question

In the example of Stacked Area via Nest, I would like to add text on each layer. Like
The position of the text doesn't really matters, just being center-right.

Answer 1

You can do something like this:
0) Calculte the center of the path using the function below:
function getMyCentroid(element) {
var bbox = element.getBBox();
return [bbox.x + bbox.width / 2, bbox.y + bbox.height / 2];
}
1) Next select all path and calculate its center.
2) Append a text and position it at the center svg.append("text")
3) Set the text associated with the path like this .text(d3.select(d).data()[0].key);
d3.selectAll(".layer")[0].forEach(function(d) {
var centroid = getMyCentroid(d);
svg.append("text").attr("x", centroid[0]).attr("y", centroid[1]).text(d3.select(d).data()[0].key);
})
var format = d3.time.format("%m/%d/%y");
var margin = {top: 20, right: 30, bottom: 30, left: 40},
width = 960 - margin.left - margin.right,
height = 500 - margin.top - margin.bottom;
var x = d3.time.scale()
.range([0, width]);
var y = d3.scale.linear()
.range([height, 0]);
var z = d3.scale.category20c();
var xAxis = d3.svg.axis()
.scale(x)
.orient("bottom")
.ticks(d3.time.days);
var yAxis = d3.svg.axis()
.scale(y)
.orient("left");
var stack = d3.layout.stack()
.offset("zero")
.values(function(d) { return d.values; })
.x(function(d) { return d.date; })
.y(function(d) { return d.value; });
var nest = d3.nest()
.key(function(d) { return d.key; });
var area = d3.svg.area()
.interpolate("cardinal")
.x(function(d) { return x(d.date); })
.y0(function(d) { return y(d.y0); })
.y1(function(d) { return y(d.y0 + d.y); });
var svg = d3.select("body").append("svg")
.attr("width", width + margin.left + margin.right)
.attr("height", height + margin.top + margin.bottom)
.append("g")
.attr("transform", "translate(" + margin.left + "," + margin.top + ")");
d3.csv("https://gist.githubusercontent.com/cyrilcherian/e6f56b1b9337142c0bde/raw/8b1728849e193db0e8b960ecb750062f4e0cb487/data.csv", function(error, data) {
if (error) throw error;
data.forEach(function(d) {
d.date = format.parse(d.date);
d.value = +d.value;
});
var layers = stack(nest.entries(data));
x.domain(d3.extent(data, function(d) { return d.date; }));
y.domain([0, d3.max(data, function(d) { return d.y0 + d.y; })]);
svg.selectAll(".layer")
.data(layers)
.enter().append("path")
.attr("class", "layer")
.attr("d", function(d) { return area(d.values); })
.style("fill", function(d, i) { return z(i); });
svg.append("g")
.attr("class", "x axis")
.attr("transform", "translate(0," + height + ")")
.call(xAxis);
svg.append("g")
.attr("class", "y axis")
.call(yAxis);
function getMyCentroid(element) {
var bbox = element.getBBox();
return [bbox.x + bbox.width / 2, bbox.y + bbox.height / 2];
}
d3.selectAll(".layer")[0].forEach(function(d) {
var centroid = getMyCentroid(d);
svg.append("text").attr("x", centroid[0]).attr("y", centroid[1]).text(d3.select(d).data()[0].key).style("fill", "red");
})
});
body {
font: 10px sans-serif;
}
.axis path,
.axis line {
fill: none;
stroke: #000;
shape-rendering: crispEdges;
}
<script src="https://cdnjs.cloudflare.com/ajax/libs/d3/3.4.11/d3.min.js"></script>
Hope this helps!