Question

如何定义X轴的值范围？

我已经使用范围0 to 1中使用小数值的示例，这显然不适用于更大的数字。

<!DOCTYPE html>
<meta charset="utf-8">
<style>

.bar rect {
  fill: steelblue;
}

.bar text {
  fill: #fff;
  font: 10px sans-serif;
}

</style>
<svg width="960" height="500"></svg>
<script src="https://d3js.org/d3.v4.min.js"></script>
<script>

// var data = d3.range(1000).map(d3.randomBates(10));
var data = [1321017167, 1421017167, 1421017167, 1421017167, 1521017167, 1521017167];

var formatCount = d3.format(",.0f");

var svg = d3.select("svg"),
    margin = {top: 10, right: 30, bottom: 30, left: 30},
    width = +svg.attr("width") - margin.left - margin.right,
    height = +svg.attr("height") - margin.top - margin.bottom,
    g = svg.append("g").attr("transform", "translate(" + margin.left + "," + margin.top + ")");

var x = d3.scaleLinear()
    .rangeRound([0, width]);

var bins = d3.histogram()
    .domain(x.domain())
    .thresholds(x.ticks(20))
    (data);

var y = d3.scaleLinear()
    .domain([0, d3.max(bins, function(d) { return d.length; })])
    .range([height, 0]);

var bar = g.selectAll(".bar")
  .data(bins)
  .enter().append("g")
    .attr("class", "bar")
    .attr("transform", function(d) { return "translate(" + x(d.x0) + "," + y(d.length) + ")"; });

bar.append("rect")
    .attr("x", 1)
    .attr("width", x(bins[0].x1) - x(bins[0].x0) - 1)
    .attr("height", function(d) { return height - y(d.length); });

bar.append("text")
    .attr("dy", ".75em")
    .attr("y", 6)
    .attr("x", (x(bins[0].x1) - x(bins[0].x0)) / 2)
    .attr("text-anchor", "middle")
    .text(function(d) { return formatCount(d.length); });

g.append("g")
    .attr("class", "axis axis--x")
    .attr("transform", "translate(0," + height + ")")
    .call(d3.axisBottom(x));

</script>

Answer 1

默认情况下，线性刻度的域为[0, 1]。您刚刚从Mike Bostock复制了该代码而未更改域。在他的原始代码中，域名巧合地是默认域名，但在您的代码中您必须定义它：

var x = d3.scaleLinear()
    .rangeRound([0, width])
    .domain(d3.extent(data))//domain here

我在这里使用d3.extent，但你可以使用你想要的任何其他数组。

以下是仅包含此更改的代码：

<!DOCTYPE html>
<meta charset="utf-8">
<style>

.bar rect {
  fill: steelblue;
}

.bar text {
  fill: #fff;
  font: 10px sans-serif;
}

</style>
<svg width="960" height="500"></svg>
<script src="https://d3js.org/d3.v4.min.js"></script>
<script>

// var data = d3.range(1000).map(d3.randomBates(10));
var data = [1321017167, 1421017167, 1421017167, 1421017167, 1521017167, 1521017167];

var formatCount = d3.format(",.0f");

var svg = d3.select("svg"),
    margin = {top: 10, right: 30, bottom: 30, left: 30},
    width = +svg.attr("width") - margin.left - margin.right,
    height = +svg.attr("height") - margin.top - margin.bottom,
    g = svg.append("g").attr("transform", "translate(" + margin.left + "," + margin.top + ")");

var x = d3.scaleLinear()
    .rangeRound([0, width])
    .domain(d3.extent(data))

var bins = d3.histogram()
    .domain(x.domain())
    .thresholds(x.ticks(20))
    (data);
    
var y = d3.scaleLinear()
    .domain([0, d3.max(bins, function(d) { return d.length; })])
    .range([height, 0]);

var bar = g.selectAll(".bar")
  .data(bins)
  .enter().append("g")
    .attr("class", "bar")
    .attr("transform", function(d) { return "translate(" + x(d.x0) + "," + y(d.length) + ")"; });

bar.append("rect")
    .attr("x", 1)
    .attr("width", x(bins[0].x1) - x(bins[0].x0) - 1)
    .attr("height", function(d) { return height - y(d.length); });

bar.append("text")
    .attr("dy", ".75em")
    .attr("y", 6)
    .attr("x", (x(bins[0].x1) - x(bins[0].x0)) / 2)
    .attr("text-anchor", "middle")
    .text(function(d) { return formatCount(d.length); });

g.append("g")
    .attr("class", "axis axis--x")
    .attr("transform", "translate(0," + height + ")")
    .call(d3.axisBottom(x));

</script>

PS：你必须调整矩形的水平位置。

直方图的X轴值

1 个答案: