Question

我是d3的新手，我试图通过条形图中的所有条形绘制平均线，但却无法实现这一点。以下是我的代码：

<!DOCTYPE html>
<html>
<head>
<meta charset=utf-8 />
<title>JS Bin</title>
<style>

body {
  font: 10px sans-serif;
}

.axis path,
.axis line {
  fill: none;
  stroke: #000;
  shape-rendering: crispEdges;
}

.bar {
  fill: steelblue;
}

.x.axis path {
  display: none;
}

.line {
  fill: none;
  stroke: #444;
  stroke-width: 1.5px;
}


</style>
</head>
<body>

<script src="//cdnjs.cloudflare.com/ajax/libs/d3/3.4.11/d3.min.js"></script>
<script>
var data=[
 {"letter": "BU", "higher": .08,"lower": .05},
 {"letter": "AU", "higher": .05,"lower": .03},
 {"letter": "LA", "higher": .04,"lower": .02}

]

var margin = {top: 20, right: 20, bottom: 30, left: 40},
    width = 960 - margin.left - margin.right,
    height = 500 - margin.top - margin.bottom;

var formatPercent = d3.format(".0%");

var x = d3.scale.ordinal()
    .rangeRoundBands([0, width], .1);

var x2 = d3.scale.ordinal()
  .rangeBands([0, width], 0);


var y = d3.scale.linear()
    .range([height, 0]);

var xAxis = d3.svg.axis()
    .scale(x)
    .orient("bottom"); 

var yAxis = d3.svg.axis()
    .scale(y)
    .orient("left")
    .tickFormat(formatPercent);

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 + ")");


  data.forEach(function(d) {
    d.higher = +d.higher;
    d.lower = +d.lower;
  });


  x.domain(data.map(function(d) { return d.letter; }));
  x2.domain(data.map(function(d) { return d.letter; }));
  y.domain([0, d3.max(data, function(d) { return d.higher; })]);

  svg.append("g")
      .attr("class", "x axis")
      .attr("transform", "translate(0," + height + ")")
      .call(xAxis);

  svg.append("g")
      .attr("class", "y axis")
      .call(yAxis)
    .append("text")
      .attr("transform", "rotate(-90)")
      .attr("y", 6)
      .attr("dy", ".71em")
      .style("text-anchor", "end")
      .text("Frequency");

  svg.selectAll(".bar")
      .data(data)
    .enter().append("rect")
      .attr("class", "bar")
      .attr("x", function(d) { return x(d.letter); })
      .attr("width", x.rangeBand())
      .attr("y", function(d) { return y(d.higher); })
      .attr("height", function(d) { return height - y(d.higher-d.lower); });

var dataSum = d3.mean(data, function(d) { return (d.higher + d.lower); }); 


 var line = d3.svg.line()
   .x(function(d, i) { 
      return x(d.letter) + i; })
    .y(function(d, i) { return y(dataSum/data.length); });
  svg.append("path")
      .datum(data)
      .attr("class", "line")
      .attr("d", line);


</script>  
</body>
</html>

正确的代码在这里＆＃39; http://jsbin.com/beyakumohi/1/edit?html＆＃39; 。线应该穿过每个柱的中心，但它只发生在第3个柱上，而且它也不会穿过它。我的代码中是否有任何错误。

Answer 1

d3.mean将为您提供完整数组的平均值。意思是，在这种情况下，你将得到平均值：

data[0].higher + data[0].lower + data[1].higher + data[1].lower + data[2].higher + data[2].lower

在这种情况下，我会说更适合编辑你的行函数，如下所示

var line = d3.svg.line()
    .x(function(d, i) { 
        return x(d.letter); })
    .y(function(d, i) { return y((d.higher + d.lower) / 2); });

在条形图中查找条形的平均值 - d3

1 个答案: