How to install d3 in vue and create a flow chart

In recent years, vue.js, as one of the mainstream technical frameworks in front-end development, has attracted more and more attention and love. As a dynamic data-driven JavaScript library, d3.js is also widely used in various data visualization scenarios. How to install and use d3.js in vue.js application? This article will introduce the flow chart of vue installation d3.

Step 1: Install d3.js

First, you need to install the d3.js library in the vue.js project, which can be achieved through the npm package manager. Open the terminal, enter the directory where the project is located, and enter the following command:

npm install d3

This will automatically download and install the d3.js library to the node_modules directory in the project.

Step 2: Introduce the d3.js library

With the installation of the d3.js library completed, we need to introduce it in the vue.js component to use it in the project. Open the component that needs to introduce d3.js, and add the following code at the top:

import * as d3 from "d3";

In this way, the d3.js library has been successfully introduced, and you can start using the various APIs of d3.js.

Step 3: Create a flowchart

Next, let’s create a simple flowchart to better understand how to draw charts in vue.js using d3.js.

First, add the following code to the component to create an SVG view:

created() {
  this.svg = d3
    .select('svg')
    .attr('width', this.width)
    .attr('height', this.height);
},
render() {
  return <svg></svg>;
},

In this example, we define a data object svg and use the d3.select() method to select SVG element and use the attr attribute to set the width and height of the SVG element to the values ​​defined in the responsive data object.

Next, create a data collection and its nodes, and connect them. In the mounted life cycle hook function of the component, add the following code:

mounted() {
  const dataset = {
    nodes: [
      { name: 'A' },
      { name: 'B' },
      { name: 'C' },
      { name: 'D' },
    ],
      edges: [
        { source: 0, target: 1 },
        { source: 1, target: 2 },
        { source: 2, target: 3 },
      ],
  };
  const nodes = this.svg.selectAll('circle')
    .data(dataset.nodes)
    .enter()
    .append('circle')
    .attr('cx', 100)
    .attr('cy', d => d.name.charCodeAt() * 10)
    .attr('r', 20)
    .style('fill', 'white')
    .style('stroke', 'black');
  const edges = this.svg.selectAll('line')
    .data(dataset.edges)
    .enter()
    .append('line')
    .attr('x1', d => nodes._groups[0][d.source].attributes.cx.value)
    .attr('y1', d => nodes._groups[0][d.source].attributes.cy.value)
    .attr('x2', d => nodes._groups[0][d.target].attributes.cx.value)
    .attr('y2', d => nodes._groups[0][d.target].attributes.cy.value)
    .attr('stroke', 'black')
    .attr('stroke-width', 1);
},

In this example, we use the API of d3.js to create a data collection dataset in the SVG view, including four nodes and Three edges connecting them.

Continue to use d3.js selectors and data binding methods to display data as circular nodes and connect them with straight lines. Finally, the position of the node is determined by defining the cx and cy attributes of the node, and the color and thickness of the edge are set by the stroke attribute.

Step 4: Run the code

Finally, run the code to see if the flow chart is drawn normally. Execute the following command in the terminal:

npm run serve

Open the address in the browser: http://localhost:8080, you can see the drawn flow chart.

Conclusion:

In the process of using d3.js, developers need to master a series of its APIs to draw various complex data visualization charts. However, in the vue.js application, we can easily install and introduce the d3.js library through npm, quickly build a flow chart, and achieve the effect of dynamically updating the view through the data binding feature of vue.js.

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