D3绘制柱状图
var margin = {top: 40, right: 20, bottom: 30, left: 40},
totalWidth = 800,
totalHeight = 500,
width = totalWidth - margin.left - margin.right,
height = totalHeight - margin.top - margin.bottom;
var formatPercent = d3.format(".0%");
// 定义比例尺
var xScale = d3.scaleBand()
.range([0, width])
.padding(0.2);
var yScale = d3.scaleLinear()
.range([height, 0]);
// 定义坐标轴
var xAxis = d3.axisBottom(xScale);
var yAxis = d3.axisLeft(yScale)
.tickFormat(formatPercent);
// 创建绘图区域
var svg = d3.select("#container")
.append("svg")
.attr("width", totalWidth)
.attr("height", totalHeight)
.append("g")
.attr("transform", "translate(" + margin.left + "," + margin.top + ")");
d3.tsv("", function(error, data) {
xScale.domain(data.map(function(d) {return d.letter;}));
yScale.domain([0, d3.max(data, function(d) {return d.frequency;})]);
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", "0.71em")
.attr("text-anchor", "end").text("频率");
svg.append("g")
.attr("class", "bars")
.selectAll(".bar")
.data(data).enter()
.append("rect").attr("class", "bar")
.attr("x", function(d) { return xScale(d.letter); })
.attr("width", xScale.bandwidth())
.attr("y", function(d) { return yScale(d.frequency); })
.attr("height", function(d) {
return height - yScale(d.frequency);
});
// 绘制图例
var legendWrap = svg.append("g");
var series = legendWrap.append("g").attr("class", "series");
series.append("circle")
.attr("stroke-width", 2)
.attr("fill", "steelblue")
.attr("stroke", "steelblue")
.attr("r", 6);
series.append("text")
.attr("font-size", "0.75em")
.attr("text-anchor", "start")
.attr("dy", ".32em")
.attr("dx", 12)
.text("英文字母");
var legendWidth = legendWrap.node().getBoundingClientRect().width;
legendWrap.attr("transform", "translate(" + (width - legendWidth) / 2 + ", -16)");
});