D3 二维图表的绘制系列（三）多列柱状图

Dear 丶 2021-11-10 09:02 373阅读 0赞

**上一篇： 基础柱状图 https://blog.csdn.net/zjw\_python/article/details/98201470**

**下一篇： 堆叠柱状图 https://blog.csdn.net/zjw\_python/article/details/98207916**

**代码结构和初始化画布的Chart对象介绍，请先看 https://blog.csdn.net/zjw\_python/article/details/98182540**

**本图完整的源码地址： https://github.com/zjw666/D3\_demo/tree/master/src/barChart/multiBarChart**

## 1 图表效果 ##

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3pqd19weXRob24_size_16_color_FFFFFF_t_70]

## 2 数据 ##

date,food,transportation,education
    Mon,30,40,50
    Tue,20,80,100
    Wed,20,50,80
    Thu,10,30,40
    Fri,15,20,35
    Sat,10,30,70
    Sun,20,50,60

## 3 关键代码 ##

**导入数据**

d3.csv('./data.csv', function(d){ 
        return { 
            date: d.date,
            food: +d.food,
            transportation: +d.transportation,
            education: +d.education
        };
    }).then(function(data){ 
    .....

**配置一些样式参数**

const config = { 
            barOuterPadding: 0.15,
            barColor: chart._colors(0),
            margins: { top: 80, left: 80, bottom: 50, right: 80},
            textColor: 'black',
            gridColor: 'gray',
            tickShowGrid: [20, 40, 60, 80, 100],
            title: '多列直方图',
            barInnerPadding: 2,
            hoverColor: 'white',
            animateDuration: 1000
        }

**尺度转换，注意与基础柱状图不同的是，Y轴的最大值为三个属性和的最大值**

/* ----------------------------尺度转换------------------------ */
        chart.scaleX = d3.scaleBand()
                        .domain(data.map((d) => d.date))
                        .range([0, chart.getBodyWidth()])
                        .padding(config.barOuterPadding);
        
        chart.scaleY = d3.scaleLinear()
                        .domain([0, d3.max(data, (d) => d3.max([d.food, d.transportation, d.education]))])
                        .range([chart.getBodyHeight(), 0])

**渲染柱形， 注意我们将数据绑定到`g`元素上，之后多个柱形平分一个`bandwidth`的宽度**

/* ----------------------------渲染柱形------------------------ */
        chart.renderBars = function(){ 
            //改变数据结构，方便渲染
            const multiData = d3.zip.apply(this, data.map((d) => { 
                let item = [];
                Object.keys(d).forEach((key) => { 
                    if (key !== 'date'){ 
                        item.push([d.date, d[key], key]);
                    }
                });
                return item;
            }));
    
            let groups = chart.body().selectAll('.g')
                                .data(multiData);
            let bars = groups.enter()
                                .append('g')
                             .merge(groups)
                                .attr('class', (d) => 'g ' + d[0][2])
                                .attr('fill', (d,i) => chart._colors(i))
                                .selectAll('.bar')
                                .data((d) => d);
                
                groups.exit()
                        .remove();
    
                bars.enter()
                        .append('rect')
                        .attr('class','bar')
                    .merge(bars)
                        .attr('x', (d) => { 
                            return chart.scaleX(d[0]) + chart.scaleX.bandwidth() / multiData.length * (data.columns.indexOf(d[2]) - 1);
                        })
                        .attr('y', chart.scaleY(0))
                        .attr('width', chart.scaleX.bandwidth() / multiData.length - config.barInnerPadding * (multiData.length-1))
                        .attr('height', 0)
                        .transition().duration(config.animateDuration)
                        .attr('height', (d) => chart.getBodyHeight() - chart.scaleY(d[1]))
                        .attr('y', (d) => chart.scaleY(d[1]));
                
                bars.exit()
                        .remove();
        }

**渲染坐标轴，与基础柱状图类似**

/* ----------------------------渲染坐标轴------------------------ */
        chart.renderX = function(){ 
            chart.svg().insert('g','.body')
                    .attr('transform', 'translate(' + chart.bodyX() + ',' + (chart.bodyY() + chart.getBodyHeight()) + ')')
                    .attr('class', 'xAxis')
                    .call(d3.axisBottom(chart.scaleX));
        }
    
        chart.renderY = function(){ 
            chart.svg().insert('g','.body')
                    .attr('transform', 'translate(' + chart.bodyX() + ',' + chart.bodyY() + ')')
                    .attr('class', 'yAxis')
                    .call(d3.axisLeft(chart.scaleY));
        }
    
        chart.renderAxis = function(){ 
            chart.renderX();
            chart.renderY();
        }

**渲染文本标签和网格线，与基础柱状图类似**

/* ----------------------------渲染文本标签------------------------ */
        chart.renderText = function(){ 
            d3.select('.xAxis').append('text')
                                .attr('class', 'axisText')
                                .attr('x', chart.getBodyWidth())
                                .attr('y', 0)
                                .attr('fill', config.textColor)
                                .attr('dy', 30)
                                .text('日期');
    
            d3.select('.yAxis').append('text')
                                .attr('class', 'axisText')
                                .attr('x', 0)
                                .attr('y', 0)
                                .attr('fill', config.textColor)
                                .attr('transform', 'rotate(-90)')
                                .attr('dy', -40)
                                .attr('text-anchor','end')
                                .text('每日支出（元）');
        }
    
        /* ----------------------------渲染网格线------------------------ */
        chart.renderGrid = function(){ 
            d3.selectAll('.yAxis .tick')
                .each(function(d, i){ 
                    if (config.tickShowGrid.indexOf(d) > -1){ 
                        d3.select(this).append('line')
                            .attr('class','grid')
                            .attr('stroke', config.gridColor)
                            .attr('x1', 0)
                            .attr('y1', 0)
                            .attr('x2', chart.getBodyWidth())
                            .attr('y2', 0);
                    }
                });
        }

**最后绑定鼠标交互事件**

/* ----------------------------绑定鼠标交互事件------------------------ */
        chart.addMouseOn = function(){ 
            //防抖函数
            function debounce(fn, time){ 
                let timeId = null;
                return function(){ 
                    const context = this;
                    const event = d3.event;
                    timeId && clearTimeout(timeId)
                    timeId = setTimeout(function(){ 
                        d3.event = event;
                        fn.apply(context, arguments);
                    }, time);
                }
            }
    
            d3.selectAll('.bar')
                .on('mouseover', function(d){ 
                    const e = d3.event;
                    const position = d3.mouse(chart.svg().node());
    
                    d3.select(e.target)
                        .attr('fill', config.hoverColor);
                    
                    chart.svg()
                        .append('text')
                        .classed('tip', true)
                        .attr('x', position[0]+5)
                        .attr('y', position[1])
                        .attr('fill', config.textColor)
                        .text( d[2] + ':' + d[1] + '元');
                })
                .on('mouseleave', function(d){ 
                    const e = d3.event;
                    
                    d3.select(e.target)
                        .attr('fill', chart._colors(data.columns.indexOf(d[2]) - 1));
                        
                    d3.select('.tip').remove();
                })
                .on('mousemove', debounce(function(){ 
                        const position = d3.mouse(chart.svg().node());
                        d3.select('.tip')
                        .attr('x', position[0]+5)
                        .attr('y', position[1]-5);
                    }, 6)
                );
        }

# 大功告成！！！ #

--------------------

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