我在流图堆栈布局中有数据，我想要的美感是将任意系列指定为中心线。这些线上方的系列（由它们在数据中的索引确定）将堆叠在顶部，而该线下方的系列将堆叠在下方。
这是一个 jsFidde。
在这个例子中，我希望 MS 和 RC 系列是单条水平线，其他组分别堆叠在它们的上方和下方。（与数据索引相反，我还可以根据一些数据属性设置中间系列，在这个例子中，最旧的日期是有意义的。）
我认为解决方案需要传递我自己的偏移函数，但我很难弄清楚内置函数是如何做的。
HTML
<div class="chart">
JS
// Adapted from https://gist.github.com/WillTurman/4631136
var data = [
{"key":"DJ","value":0,"date":"1/8/13"},
{"key":"DJ","value":0,"date":"1/9/13"},
{"key":"DJ","value":0,"date":"1/10/13"},
{"key":"DJ","value":1,"date":"1/11/13"},
{"key":"DJ","value":1,"date":"1/12/13"},
{"key":"MS","value":0,"date":"1/8/13"},
{"key":"MS","value":1,"date":"1/9/13"},
{"key":"MS","value":1,"date":"1/10/13"},
{"key":"MS","value":1,"date":"1/11/13"},
{"key":"MS","value":1,"date":"1/12/13"},
{"key":"RC","value":0,"date":"1/8/13"},
{"key":"RC","value":1,"date":"1/9/13"},
{"key":"RC","value":1,"date":"1/10/13"},
{"key":"RC","value":1,"date":"1/11/13"},
{"key":"RC","value":1,"date":"1/12/13"},
{"key":"CG","value":0,"date":"1/8/13"},
{"key":"CG","value":0,"date":"1/9/13"},
{"key":"CG","value":0,"date":"1/10/13"},
{"key":"CG","value":0,"date":"1/11/13"},
{"key":"CG","value":1,"date":"1/12/13"},
{"key":"RI","value":0,"date":"1/8/13"},
{"key":"RI","value":0,"date":"1/9/13"},
{"key":"RI","value":0,"date":"1/10/13"},
{"key":"RI","value":0,"date":"1/11/13"},
{"key":"RI","value":1,"date":"1/12/13"}
]
chart(data, "pink");
var datearray = [];
var colorrange = [];
function chart(data, color) {
if (color == "blue") {
colorrange = ["#045A8D", "#2B8CBE", "#74A9CF", "#A6BDDB", "#D0D1E6", "#F1EEF6"];
}
else if (color == "pink") {
colorrange = ["#980043", "#DD1C77", "#DF65B0", "#C994C7", "#D4B9DA", "#F1EEF6"];
}
else if (color == "orange") {
colorrange = ["#B30000", "#E34A33", "#FC8D59", "#FDBB84", "#FDD49E", "#FEF0D9"];
}
strokecolor = colorrange[0];
var format = d3.time.format("%m/%d/%y");
var margin = {top: 20, right: 40, bottom: 30, left: 30};
var width = document.body.clientWidth - margin.left - margin.right;
var height = 400 - margin.top - margin.bottom;
var tooltip = d3.select("body")
.append("div")
.attr("class", "remove")
.style("position", "absolute")
.style("z-index", "20")
.style("visibility", "hidden")
.style("top", "30px")
.style("left", "55px");
var x = d3.time.scale()
.range([0, width]);
var y = d3.scale.linear()
.range([height-10, 0]);
var z = d3.scale.ordinal()
.range(colorrange);
var xAxis = d3.svg.axis()
.scale(x)
.orient("bottom")
.ticks(d3.time.weeks);
var yAxis = d3.svg.axis()
.scale(y);
var yAxisr = d3.svg.axis()
.scale(y);
var stack = d3.layout.stack()
.offset("silhouette")
.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("linear")
.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(".chart").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 + ")");
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")
.attr("transform", "translate(" + width + ", 0)")
.call(yAxis.orient("right"));
svg.append("g")
.attr("class", "y axis")
.call(yAxis.orient("left"));
svg.selectAll(".layer")
.attr("opacity", 1)
.on("mouseover", function(d, i) {
svg.selectAll(".layer").transition()
.duration(250)
.attr("opacity", function(d, j) {
return j != i ? 0.6 : 1;
})})
.on("mousemove", function(d, i) {
mousex = d3.mouse(this);
mousex = mousex[0];
var invertedx = x.invert(mousex);
invertedx = invertedx.getMonth() + invertedx.getDate();
var selected = (d.values);
for (var k = 0; k < selected.length; k++) {
datearray[k] = selected[k].date
datearray[k] = datearray[k].getMonth() + datearray[k].getDate();
}
mousedate = datearray.indexOf(invertedx);
pro = d.values[mousedate].value;
d3.select(this)
.classed("hover", true)
.attr("stroke", strokecolor)
.attr("stroke-width", "0.5px"),
tooltip.html( "<p>" + d.key + "<br>" + pro + "</p>" ).style("visibility", "visible");
})
.on("mouseout", function(d, i) {
svg.selectAll(".layer")
.transition()
.duration(250)
.attr("opacity", "1");
d3.select(this)
.classed("hover", false)
.attr("stroke-width", "0px"), tooltip.html( "<p>" + d.key + "<br>" + pro + "</p>" ).style("visibility", "hidden");
})
var vertical = d3.select(".chart")
.append("div")
.attr("class", "remove")
.style("position", "absolute")
.style("z-index", "19")
.style("width", "1px")
.style("height", "380px")
.style("top", "10px")
.style("bottom", "30px")
.style("left", "0px")
.style("background", "#fff");
d3.select(".chart")
.on("mousemove", function(){
mousex = d3.mouse(this);
mousex = mousex[0] + 5;
vertical.style("left", mousex + "px" )})
.on("mouseover", function(){
mousex = d3.mouse(this);
mousex = mousex[0] + 5;
vertical.style("left", mousex + "px")});
}