README.md

d3-tube-map

Draw tube maps in the style of the London Underground using d3.

See a demo on bl.ocks.org or Observable.

A word of warning. This was created to scratch my own itch (Cambridge Pub Map). It works, but can be difficult to work with. That said, here are examples of other people creating awesome visualizations:

• Lisbon Schematic Metro Map
• Berlin U-Bahn Map

Installing

If you use NPM, npm install d3-tube-map. Otherwise, download the latest release. AMD, CommonJS, and vanilla environments are supported. In vanilla, a d3 global is exported:

<script src="https://d3js.org/d3.v6.js"></script>
<script src="../dist/d3-tube-map.js"></script>

<script>
  var container = d3.select("#tube-map");

  var width = 1600;
  var height = 1024;

  var map = d3
    .tubeMap()
    .width(width)
    .height(height)
    .margin({
      top: height / 50,
      right: width / 7,
      bottom: height / 10,
      left: width / 7,
    });

  d3.json("./pubs.json").then(function (data) {
    container.datum(data).call(map);
  });
</script>

API Reference

# d3.tubeMap() <>

Constructs a new tube map generator with the default settings.

# tubeMap(selection) <>

Render the tube map to the given selection, which is a selection.

# tubeMap.width(w) <>

Sets the width of the viewbox the map is rendered to.

# tubeMap.height(h) <>

Sets the height of the viewbox the map is rendered to.

# tubeMap.margin(m) <>

Sets the margin around the map. Takes an object of the following form:

{ top: 10, right: 20, bottom: 10, left: 20 }

Input Data Format

The data passed to the tube map should have the following properties: stations, lines and optionally river. A minimal example is shown below.

{
  "stations": {
    "StationA": {
      "label": "Station A"
    },
    "StationB": {
      "label": "Station B"
    }
  },
  "lines": [
    {
      "name": "LineA",
      "color": "#FF0000",
      "shiftCoords": [0, 0],
      "nodes": [
        {
          "coords": [23, -4],
          "name": "StationA",
          "labelPos": "N"
        },
        {
          "coords": [30, -4]
        },
        {
          "coords": [31, -3],
        },
        {
          "coords": [31, 2],
          "name": "StationB",
          "labelPos": "E"
        }
      ]
    }
  ]
}

stations is an object where each property is a a station with the key being a unique identifier and the value being an object with a label property. The label is the display friendly text that will be rendered to the screen.

lines is an array of line objects. Each line must have the following:

• name will be used as the id of the svg path element
• color is simply the color of the line
• shiftCoords will translate the whole line in the x and y directions
• nodes is an array of nodes which define the layout of the line

A line may optionally also define:

• shiftNormal will offset the line along the direction of its normal vector

Each node must have the following:

• coords is the position of the node. Must be integer values
• name should be present if the node represents a station. It should match a station defined in the top-level stations property
• labelPos should be present if the node represents a station. It is a compass direction and determines where the label is positioned relative to the node, e.g. NE would place the label up and to the right of the node

Corners

Two types of corner are supported: a 90 degree turn and a 45 degree turn. The latter is recognised when the position of a node differs from the position of the previous node by either:

• 1 in the x direction and 2 in the y direction
• 2 in the x direction and 1 in the y direction

For example:

[
  {
    "coords": [-27, -11]
  },
  {
    "coords": [-26, -9]
  }
]

A 90 degree turn is recognised when the position of a node differs from the position of the previous node by:

• 1 in the x direction and 1 in the y direction

For example:

[
  {
    "coords": [0, 2]
  },
  {
    "coords": [1, 1],
  }
]