var url = "https://gist.githubusercontent.com/amandabee/edf73bc0bbe131435c952f5ed47524a6/raw/99febb9971f76e36af06f1b99913fcaa645ecb3e/election.csv"
var m = {top: 10, right: 10, bottom: 50, left: 110},
w = 800 - m.left - m.right,
h = 500 - m.top - m.bottom,
pad = .1;
var x = d3.scale.linear().range([0, w]);
y0 = d3.scale.ordinal().rangeRoundBands([0, h], pad);
var color = d3.scale.category20c();
var yAxis = d3.svg.axis()
.scale(y0)
.orient("left");
var xAxis = d3.svg.axis()
.scale(x)
.orient("bottom")
.ticks(5)
.tickFormat(d3.format("$,.0f"));
var svg = d3.select("#chart").append("svg")
.attr("width", w + m.right + m.left + 100)
.attr("height", h + m.top + m.bottom)
.append("g")
.attr("transform",
"translate(" + m.left + "," + m.top + ")");
d3.csv(url, function(error, data) {
data.forEach(function(d) {
d.votes = +d.votes;
});
y0.domain(data.map(function(d) { return d.district; }));
districtD = d3.nest()
.key(function(d) { return d.district; })
.rollup(function(d){
console.log(d);
return d3.scale.ordinal()
.domain(d.map(function(c){return c.candidate}))
.rangeRoundBands([0, y0.rangeBand()], pad);
})
.map(data);
x.domain([0, d3.max(data, function(d) {
return d.votes;
})]);
svg.append("g")
.attr("class", "x axis")
.attr("transform", "translate(0," + h + ")")
.call(xAxis)
.selectAll("text")
.style("text-anchor", "middle");
svg.append("g")
.attr("class", "y axis")
.call(yAxis)
.append("text");
svg.selectAll("bar")
.data(data)
.enter().append("rect")
.style("fill", function(d,i) {
return color(d.district);
})
.attr("x", 0)
.attr("y", function(d) { return y0(d.district) + districtD[d.district](d.candidate); })
.attr("height", function(d){
return districtD[d.district].rangeBand();
})
.attr("width", function(d) {
return x(d.votes);
});
svg.selectAll(".label")
.data(data)
.enter().append("text")
.text(function(d) {
return (d.votes);
})
.attr("text-anchor", "start")
.attr("x", function(d) { return x(d.votes)})
.attr("y", function(d) { return y0(d.district) + districtD[d.district](d.candidate) + districtD[d.district].rangeBand()/2;})
.attr("class", "axis");
});
.axis {
font: 10px sans-serif;
}
.axis path, .axis line {
fill: none;
stroke: black;
shape-rendering: crispEdges;
}
<script src="https://cdnjs.cloudflare.com/ajax/libs/d3/3.4.11/d3.min.js"></script>
<div id="chart"></div>
bar_width = (width - (num_dist * group_pad)) / (num_candidates + num_dists) - cand_pad
然后对于每个组...group_width = (bar_width + cand_pad) * num_candidates
。 - Amanda