link

Overview

The link mark is similar to a line chart but specifies x and y channels as field arrays of length 2. It obtains corresponding positioning points (x, y) by pairing them and connects the corresponding positioning points to draw directional line segments (with arrows).

import { Chart } from '@antv/g2';

const chart = new Chart({
  container: 'container',
});

chart.options({
  type: 'link',
  height: 260,
  autoFit: true,
  data: [
    { x1: 10, y1: 10, x2: 20, y2: 20, type: '1' },
    { x1: 21, y1: 12, x2: 11, y2: 22, type: '1' },
    { x1: 20, y1: 21, x2: 10, y2: 11, type: '2' },
    { x1: 11, y1: 23, x2: 21, y2: 13, type: '2' },
  ],
  encode: { x: ['x1', 'x2'], y: ['y1', 'y2'], color: 'type' }, // The link mark requires x, x1, y, y1 channels to define a line or vector between two points
  style: { arrow: true, arrowSize: 6 }, // arrow is the arrow switch, arrows can usually represent direction, which is the difference between link and line marks.
  legend: false,
});

chart.render();

For more examples, please check the Chart Examples - Link page.

Options

Property	Description	Type	Default	Required
encode	Configure the visual channels of the `link` mark, including `x`, `y`, `color`, `shape`, etc., to specify the relationship between visual element properties and data	encode	-	✓
style	Configure the graphic style of the `link` mark	style	-

encode

Configure the visual channels of the area mark.

Property	Description	Type	Default	Required
x	Bind the `x` property channel of the `link` mark, can be a single string representing the `x` channel, or directly through an array for both `x` and `x1` channels	encode	-	✓
x1	Bind the `x1` property channel of the `link` mark, representing the `x` value of the ending direction point.	encode	-	✓
y	Bind the `y` property channel of the `link` mark, can be a single string representing the `y` channel, or directly through an array for both `y` and `y1` channels	encode	-	✓
y1	Bind the `y1` property channel of the `link` mark, representing the `y` value of the ending direction point.	encode	-	✓
color	Bind the `color` property channel of the `link` mark. If a data field is mapped to the color channel, the data will be grouped and split into multiple areas with different colors, which can be used to divide areas or present the values of the current area	encode	-
shape	Bind the `shape` property channel of the `link` mark	encode	`link`

x & y & x1 & y1

The link mark’s visual channels require values for the four fields x, y, x1, y1. The supported data formats are as follows:

Direct configuration of x, y

{
  type: 'link',
  data: [
    { x: 10, y: 10, x1: 20, y1: 20 },
  ],
  encode: { x: ['x','x1'], y: ['y','y1'] }
}

Separate configuration of x, y, x1, y1

{
  type: 'link',
  data: [
    { x: 10, y: 10, x1: 20, y1: 20 },
  ],
  encode: { x: 'x', y: 'y', x1:'x1',y1:'y1' }
}

color

The color visual channel affects the link mark. A single area in the link mark can only use one color (or gradient color), but if a data field is mapped to the color channel, the data will be grouped and split into multiple areas:

import { Chart } from '@antv/g2';

const chart = new Chart({
  container: 'container',
});

chart.options({
  type: 'link',
  autoFit: true,
  data: {
    type: 'fetch',
    value: 'https://gw.alipayobjects.com/os/antfincdn/SM13%24lHuYH/metros.json',
  },
  encode: {
    x: ['POP_1980', 'POP_2015'],
    y: ['R90_10_1980', 'R90_10_2015'],
    color: (d) => d.R90_10_2015 - d.R90_10_1980, // color is a numerical mapping, changing color based on the mapped value. Currently represents length, different lengths will display colors in gradient
  },
  scale: { x: { type: 'log' } },
  style: { arrow: true, arrowSize: 6 },
  axis: { x: { labelFormatter: '~s', labelTransform: 'rotate(90)' } },
  legend: false,
  tooltip: { title: { channel: 'color', valueFormatter: '.1f' } },
});

chart.render();

shape

The built-in shapes supported by the link mark are as follows:

Shape	Description	Example
link	Connection line\|vector
arc	Arc line
smooth	Bezier curve
vhv	Right-angle polyline

style

Property	Description	Type	Default
arrow	Control whether to show arrows. Essentially a line segment, not a graphic, inherits all properties of straight lines.	boolean	`false`
arrowSize	The size of the arrow icon, can specify pixel values or relative values of arrow length. This property is for arrow length, width is configured by ‘lineWidth’	string \| number	`40%`
stroke	The color of the graphic	string \| Function<string>	-
strokeOpacity	Graphic transparency	number \| Function<number>	-
lineWidth	The width of the graphic	number \| Function<number>	-
lineDash	Dashed line configuration for stroke, the first value is the length of each dash segment, the second value is the distance between segments. Setting lineDash to [0, 0] results in no stroke. Since arrows also inherit line style configuration, it’s best not to configure this style when using arrows	[number,number] \| Function<[number, number]>	-
opacity	Overall transparency of the graphic	number \| Function<number>	-
shadowColor	Graphic shadow color	string \| Function<string>	-
shadowBlur	Gaussian blur coefficient of the graphic shadow	number \| Function<number>	-
shadowOffsetX	Set the horizontal distance of the shadow from the graphic	number \| Function<number>	-
shadowOffsetY	Set the vertical distance of the shadow from the graphic	number \| Function<number>	-
cursor	Mouse style. Same as CSS mouse style, default ‘default’.	string \| Function<string>	`default`

import { Chart } from '@antv/g2';

const chart = new Chart({
  container: 'container',
});

chart.options({
  type: 'link',
  height: 260,
  autoFit: true,
  data: [{ x1: 10, y1: 10, x2: 20, y2: 20 }],
  encode: { x: ['x1', 'x2'], y: ['y1', 'y2'] },
  style: {
    arrow: true,
    arrowSize: 6, // arrow length
    lineWidth: 8, // line width
    stroke: '#1f1aa1', // color
    opacity: 0.7,
  },
  legend: false,
});

chart.render();

Examples

How to specify the length of arrow icons?

There are two ways to specify the length of arrow icons: one is by entering pixel values, such as 40, to specify a fixed length; the other is by specifying a percentage, such as 30%, to specify a relative length based on the arrow length reference. The default value is 40%. Example as follows:

chart.options({
  type: 'link',
  // ...
  style: {
    arrowSize: 40,
    // arrowSize: '30%',
  },
});