使用带有多个y轴的D3画笔

MattDionis 发表于 Dev

马特·狄奥尼斯

我创建了一个D3可视化文件，其中包含散点图和折线图。它们共享一个x轴，但是每个都有自己的y轴。我的问题涉及如何正确实现画笔并更新两个y轴。

如您所见，y轴最初是正确的，一旦刷子关闭，y轴也将正确。但是，在“刷”期间，两个y轴都设置为“左”轴。我在这里设置画笔时明白了为什么会这样：

brush = d3.svg.brush()
  .x(brushFilterXScale)
  .y(brushFilterTransactionsYScale)
  .on('brush', brushed);

我也有一个brushFilterBalanceYScale右边的轴比例尺。我的问题是如何同时将这两个比例传递给brush我，以便可以正确更新每个y轴？

标记

我不知道这样做的直接方法。但是，您可以在brush事件中反向映射它：

function brushed() {

  var extent = brush.extent(), //<-- the extent
      yDomain =  [extent[0][1], extent[1][1]]; //<-- the y domain of the extent

  y2.domain(
    [
      y2Brush.invert(yBrush(yDomain[0])), //<-- take the yDomain start, get it's pixel position, then invert that back into the domain of the y2Brush
      y2Brush.invert(yBrush(yDomain[1]))
    ]
  );

这是一个工作示例：

<!DOCTYPE html>
<meta charset="utf-8">
<style>
  svg {
    font: 10px sans-serif;
  }
  
  .line {
    fill: none;
    stroke: steelblue;
    clip-path: url(#clip);
  }
  
  circle {
    clip-path: url(#clip);
  }
  
  .axis path,
  .axis line {
    fill: none;
    stroke: #000;
    shape-rendering: crispEdges;
  }
  
  .brush .extent {
    stroke: #fff;
    fill-opacity: .125;
    shape-rendering: crispEdges;
  }
</style>

<body>
  <script src="//d3js.org/d3.v3.min.js"></script>
  <script>
    var margin = {
        top: 10,
        right: 40,
        bottom: 100,
        left: 40
      },
      margin2 = {
        top: 430,
        right: 40,
        bottom: 20,
        left: 40
      },
      width = 500 - margin.left - margin.right,
      height = 500 - margin.top - margin.bottom,
      height2 = 500 - margin2.top - margin2.bottom;


    var x = d3.scale.linear().range([0, width])
      y = d3.scale.linear().range([height, 0]),
      y2 = d3.scale.linear().range([height, 0]),
      xBrush = d3.scale.linear().range([0,width]),
      yBrush = d3.scale.linear().range([height2, 0]),
      y2Brush = d3.scale.linear().range([height2, 0]);

    var xAxis = d3.svg.axis().scale(x).orient("bottom"),
      yAxis = d3.svg.axis().scale(y).orient("left"),
      yAxis2 = d3.svg.axis().scale(y2).orient("right"),
      yAxisBrush = d3.svg.axis().scale(yBrush).orient("bottom");
      xAxisBrush = d3.svg.axis().scale(xBrush).orient("bottom");

    var brush = d3.svg.brush()
      .x(xBrush)
      .y(yBrush)
      .on("brush", brushed);

    var line = d3.svg.line()
      .interpolate("monotone")
      .x(function(d) {
        return x(d.x);
      })
      .y(function(d) {
        return y(d.y);
      });

    var lineBrush = d3.svg.line()
      .interpolate("monotone")
      .x(function(d) {
        return x(d.x);
      })
      .y(function(d) {
        return yBrush(d.y);
      });

    var svg = d3.select("body").append("svg")
      .attr("width", width + margin.left + margin.right)
      .attr("height", height + margin.top + margin.bottom);

    svg.append("defs").append("clipPath")
      .attr("id", "clip")
      .append("rect")
      .attr("width", width)
      .attr("height", height);

    var focus = svg.append("g")
      .attr("class", "focus")
      .attr("transform", "translate(" + margin.left + "," + margin.top + ")");

    var context = svg.append("g")
      .attr("class", "context")
      .attr("transform", "translate(" + margin2.left + "," + margin2.top + ")");

    var data1 = [],
      data2 = [];
    for (var i = 0; i < 100; i++) {
      data1.push({
        x: i,
        y: Math.random() * 10
      });
      if (i % 3 === 0){
        data2.push({
          x: i,
          y: Math.random() * 100
        });
      }
    }

    x.domain([0,100]);
    y.domain([0, d3.max(data1.map(function(d) {
      return d.y;
    }))]);
    y2.domain([0, d3.max(data2.map(function(d) {
      return d.y;
    }))]);
    xBrush.domain(x.domain());
    yBrush.domain(y.domain());
    y2Brush.domain(y2.domain());

    focus.append("path")
      .datum(data1)
      .attr("class", "line")
      .attr("d", line);
      
    var scatter = focus.append("g")
      .selectAll("circle")
      .data(data2);
      
    scatter
      .enter()
      .append("circle")
      .attr("cx", function(d){
        return x(d.x);
      })
      .attr("cy", function(d){
        return y2(d.y);
      })
      .attr("r", function(d){
        d.r = Math.random() * 20;
        return d.r;
      })
      .style("fill", "orange")
      .style("opacity", "0.5");
      
    focus.append("g")
      .attr("class", "x axis")
      .attr("transform", "translate(0," + height + ")")
      .call(xAxis);

    focus.append("g")
      .attr("class", "y axis")
      .call(yAxis);
      
     focus.append("g")
      .attr("transform", "translate(" + width + " ,0)")	
      .attr("class", "y2 axis")
      .call(yAxis2);

    context.append("path")
      .datum(data1)
      .attr("class", "line")
      .attr("d", lineBrush);
      
    context.append("g")
      .selectAll("circle")
      .data(data2)
      .enter()
      .append("circle")
      .attr("cx", function(d){
        return x(d.x);
      })
      .attr("cy", function(d){
        return y2Brush(d.y);
      })
      .attr("r", function(d){
        return d.r * 0.25;
      })
      .style("fill", "orange")
      .style("opacity", "0.5");

    context.append("g")
      .attr("class", "x axis")
      .attr("transform", "translate(0," + height2 + ")")
      .call(xAxisBrush);

    context.append("g")
      .attr("class", "x brush")
      .call(brush)
      .selectAll("rect")
      .attr("y", -6)
      .attr("height", height2 + 7);

    function brushed() {
      
      var extent = brush.extent(),
          yDomain =  [extent[0][1], extent[1][1]];

      y2.domain([y2Brush.invert(yBrush(yDomain[0])), y2Brush.invert(yBrush(yDomain[1]))]);
      x.domain(brush.empty() ? xBrush.domain() : [extent[0][0], extent[1][0]]);
      y.domain(brush.empty() ? yBrush.domain() : yDomain);
      
      scatter
        .attr("cx", function(d){
          return x(d.x);
        })
        .attr("cy", function(d){
          return y2(d.y);
        })
      
      focus.select(".line").attr("d", line);
      focus.select(".x.axis").call(xAxis);
      focus.select(".y.axis").call(yAxis);
      focus.select(".y2.axis").call(yAxis2);
    }

  </script>