多系列折线图

Question

我正在尝试创建多折线图。我找到了 this question which seems to be doing similar to what I am trying to do, but the example doesn't seem to be complete as I cannot get it to run. Below is the most minimal example I could create to demonstrate what I am trying to do, however it is not working. It should create a line series chart with two series, one for open, one for close. I have tried to use the same principle as used in the HTML table example here。我正在使用 d3 版本 5.

const data = [
  { date: "Wed, 14 Aug 2019 00:00:00 GMT", close: 2.92, open: 3.2 },
  { date: "Wed, 28 Aug 2019 00:00:00 GMT", close: 2.89, open: 2.99 },
  { date: "Fri, 30 Aug 2019 00:00:00 GMT", close: 2.88, open: 3.4 },
  { date: "Mon, 02 Sep 2019 00:00:00 GMT", close: 2.89, open: 3.5 },
];

const margin = { top: 20, right: 20, bottom: 30, left: 50 };
const width = 960 - margin.left - margin.right;
const height = 500 - margin.top - margin.bottom;

// set the ranges
const x = d3
  .scaleTime()
  .domain(d3.extent(data, d => d.date)) 
  .range([0, width]);
const y = d3
  .scaleLinear()
  .domain([0, 4])
  .range([height, 0]);

const g = 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})`);

const seriesNames = ["open", "close"]

// create array where each element is a dataset for a specific series
const transformedData = seriesNames.map(colName => data.map(row => ({ date: row.date, value: row[colName] })));

const valueline = d3
  .line()
  .x(d => x(d.date))
  .y(d => y(d.value));

let series = g
  .selectAll("path")
  .data(seriesNames)
  .enter()
  .append("path") // create path for each series
  .data(colName => transformedData[colName]) // bind series-specific dataset to path
  .attr("d", valueline) // create line from series-specific dataset
  .attr("stroke", "red")
  .attr("fill", "none");

// Add the X Axis
g.append("g")
  .attr("transform", `translate(0,${height})`)
  .call(d3.axisBottom(x));

// Add the Y Axis
g.append("g").call(d3.axisLeft(y));

Answer 1

两件事：首先，将数据数组直接传递给 data 方法：

let series = g
  .selectAll("path")
  .data(transformedData)
  //etc...

其次，你有一个时间尺度。因此，使用日期，而不是字符串：

data.forEach(d => d.date = new Date(d.date));

这是您的代码，其中包含这两项更改：

const data = [{
    date: "Wed, 14 Aug 2019 00:00:00 GMT",
    close: 2.92,
    open: 3.2
  },
  {
    date: "Wed, 28 Aug 2019 00:00:00 GMT",
    close: 2.89,
    open: 2.99
  },
  {
    date: "Fri, 30 Aug 2019 00:00:00 GMT",
    close: 2.88,
    open: 3.4
  },
  {
    date: "Mon, 02 Sep 2019 00:00:00 GMT",
    close: 2.89,
    open: 3.5
  },
];

data.forEach(d => d.date = new Date(d.date));

const margin = {
  top: 20,
  right: 20,
  bottom: 30,
  left: 50
};
const width = 960 - margin.left - margin.right;
const height = 500 - margin.top - margin.bottom;

// set the ranges
const x = d3
  .scaleTime()
  .domain(d3.extent(data, d => d.date))
  .range([0, width]);
const y = d3
  .scaleLinear()
  .domain([0, 4])
  .range([height, 0]);

const g = 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})`);

const seriesNames = ["open", "close"]

// create array where each element is a dataset for a specific series
const transformedData = seriesNames.map(colName => data.map(row => ({
  date: row.date,
  value: row[colName]
})));

const valueline = d3
  .line()
  .x(d => x(d.date))
  .y(d => y(d.value));

let series = g
  .selectAll("path")
  .data(transformedData)
  .enter()
  .append("path") // create path for each series
  .attr("d", valueline) // create line from series-specific dataset
  .attr("stroke", "red")
  .attr("fill", "none");

// Add the X Axis
g.append("g")
  .attr("transform", `translate(0,${height})`)
  .call(d3.axisBottom(x));

// Add the Y Axis
g.append("g").call(d3.axisLeft(y));

<script src="https://cdnjs.cloudflare.com/ajax/libs/d3/5.7.0/d3.min.js"></script>

多系列折线图

Multiple series line chart

javascript

linechart

d3.js