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react-simple-maps

An svg map component built with and for React. It allows the creation of pure react svg maps.

Why

React-simple-maps aims to make working with svg maps in react easier. It handles tasks such as panning, zooming and simple rendering optimization, and takes advantage of parts of d3-geo and topojson-client instead of relying on the entire d3 library.

Since react-simple-maps leaves DOM work to react, it can also be easily used with other libraries, such as react-motion and redux-tooltip.

❗ API changes from 0.9 to 0.10

In version 0.10 the method of passing geography data to react-simple-maps has changed. Where previously geographyUrl and geographyPaths were separate, they are now handled together through the geography prop. If you are upgrading from version 0.9, simply change geographyUrl or geographyPaths to geography and you should be good to go.

Installation

To install react-simple-maps

$ npm install react react-dom react-simple-maps --save

Usage

React-simple-maps exposes a set of components that can be combined to create svg maps with markers and annotations. In order to render a map you have to provide a reference to a valid topojson file. You can find example topojson files in the topojson-maps folder or on topojson world-atlas. To learn how to make your own topojson maps from shapefiles, please read "How to convert and prepare TopoJSON files for interactive mapping with d3" on medium.

import React, { Component } from "react"
import ReactDOM from "react-dom"
import {
  ComposableMap,
  ZoomableGroup,
  Geographies,
  Geography,
} from "react-simple-maps"

class App extends Component {
  render() {
    return(
      <div>
        <ComposableMap>
          <ZoomableGroup>
          <Geographies geography={ "/path/to/your/topojson-map-file.json or geography object" }>
            {(geographies, projection) => geographies.map(geography => (
              <Geography
                key={ geography.id }
                geography={ geography }
                projection={ projection }
                />
            ))}
          </Geographies>
          </ZoomableGroup>
        </ComposableMap>
      </div>
    )
  }
}

document.addEventListener("DOMContentLoaded", () => {
  ReactDOM.render(<App />, document.getElementById("app"))
})

Here is the complete simplified component structure of any map created with react-simple-maps.

<ComposableMap>
  <ZoomableGroup>
    <Geographies geography={ "/path/to/your/topojson-map-file.json or geography object" }>
      {(geographies, projection) => geographies.map(geography => (
        <Geography key={ geography.id } geography={ geography } projection={ projection } />
      ))}
    </Geographies>
    <Markers>
      <Marker />
    </Markers>
    <Lines>
      <Line />
    </Lines>
    <Annotation />
  </ZoomableGroup>
</ComposableMap>

The above results in the following svg structure rendered by react:

<svg class="rsm-svg">
  <g class="rsm-zoomable-group">
    <g class="rsm-geographies">
      <path class="rsm-geography" />
      <path class="rsm-geography" />
      <path class="rsm-geography" />
      ...
    </g>
    <g class="rsm-markers">
      <g class="rsm-marker"></g>
    </g>
    <g class="rsm-lines">
      <path class="rsm-line"></g>
    </g>
    <g class="rsm-annotation"></g>
  </g>
</svg>

Components

React-simple-maps is a set of components that simplify the process of making interactive svg maps with react. The components included are:

<ComposableMap />

<ComponentMap /> forms the wrapper around your map. It defines the dimensions of the map and sets the projection used by Geographies, Markers, and Annotations, to position elements. By default the maps use the "times" projection, but react-simple-maps also supports robinson, eckert4, winkel3, mercator, and miller projections out of the box. Additionally you can plug in a custom projection of your choice. All projections from d3-geo-projections are supported.

Props
Property Type Default
width Number 800
height Array 450
projection String/Function "times"
projectionConfig Object *see examples below
defs SVG Def Element *see defs spec
Configuring projections

The following custom configuration would prevent a visual split of Russia.

...
<ComposableMap
  projectionConfig={{
    scale: 200,
    rotation: [-10,0,0],
  }}
>
...
</ComposableMap>
...

The default configuration of the projection:

{
  scale: 160,
  xOffset: 0,
  yOffset: 0,
  rotation: [0,0,0],
  precision: 0.1,
}

<ZoomableGroup />

<ZoomableGroup /> is a component that allows you to zoom and pan. Check out the zoom example to find out how to work with zoom in react-simple-maps.

Props
Property Type Default
zoom Number 1
center Array [0,0]
disablePanning Boolean false
style Object {}
onMoveStart Function  
onMoveEnd Function  
Zooming

The ZoomableGroup component exposes a zoom property, which can be updated from a wrapper component via setState.

import React, { Component } from "react"
import ReactDOM from "react-dom"
import {
  ComposableMap,
  ZoomableGroup,
  Geographies,
  Geography,
} from "react-simple-maps"

class App extends Component {
  constructor() {
    super()

    this.state = {
      zoom: 1,
    }

    this.handleZoomIn = this.handleZoomIn.bind(this)
    this.handleZoomOut = this.handleZoomOut.bind(this)
  }
  handleZoomIn() {
    this.setState({
      zoom: this.state.zoom * 2,
    })
  }
  handleZoomOut() {
    this.setState({
      zoom: this.state.zoom / 2,
    })
  }
  render() {
    return(
      <div>
        <button onClick={ this.handleZoomIn }>{ "Zoom in" }</button>
        <button onClick={ this.handleZoomOut }>{ "Zoom out" }</button>
        <hr />
        <ComposableMap>
          <ZoomableGroup zoom={ this.state.zoom }>
          <Geographies geography={ "/path/to/your/topojson-map-file.json or geography object" }>
            {(geographies, projection) => geographies.map(geography => (
              <Geography
                key={ geography.id }
                geography={ geography }
                projection={ projection }
                />
            ))}
          </Geographies>
          </ZoomableGroup>
        </ComposableMap>
      </div>
    )
  }
}

document.addEventListener("DOMContentLoaded", () => {
  ReactDOM.render(<App />, document.getElementById("app"))
})
Move events

The ZoomableGroup component allows you to hook into the onMoveStart and onMoveEnd event, and exposes the new center of the map in the callback.

handleMoveStart(currentCenter) {
  console.log("New center: ", currentCenter)
}

handleMoveEnd(newCenter) {
  console.log("New center: ", newCenter)
}

...
<ZoomableGroup
  onMoveStart={this.handleMoveStart}
  onMoveEnd={this.handleMoveEnd}
>
  <Geographies>
    ...
  </Geographies>
</ZoomableGroup>
...

<ZoomableGlobe />

<ZoomableGlobe /> is a component used as a replacement for <ZoomableGroup /> when making SVG globes. While <ZoomableGroup /> is used for zooming and panning, <ZoomableGlobe /> is used for zooming and rotation.

Props
Property Type Default
zoom Number 1
center Array [0,0]
style Object {}
onMoveStart Function  
onMoveEnd Function  

Note that if you are using the <ZoomableGlobe /> component together with the graticule, you will have to specify <Graticule globe={true} /> for the graticule. See the globe example for more information on how to use the <ZoomableGlobe /> component.

<Geographies />

<Geographies /> is a group wrapper around the geographies paths. It returns a function that contains the geographies extracted from the data passed ot the geography prop.

React-simple-maps offers a couple of ways to optimise the performance of the map:

  1. By default the <Geographies /> component uses shouldComponentUpdate to prevent the paths from being rerendered. This optimisation can be bypassed using the disableOptimization prop. This is useful when making choropleth maps that are updated on user interaction.

  2. A second way in which react-simple-maps can optimise maps is by setting a cacheId on the individual geographies. See the <Geography /> component for more info. The unique cacheIds help to cache the paths and significantly accelerate rerenders. This second method is the recommended way of optimising maps with react-simple-maps.

If you do not want react-simple-maps to load your topojson and pass it down automatically, you can also pass your topojson converted features directly into the Geographies component, or an object containing the topojson data.

Props
Property Type Default
disableOptimization Boolean false
geography String or Object, or Array ""
Choropleth map

The below example uses the world-50m.json TopoJSON file.

import React, { Component } from "react"
import { scaleLinear } from "d3-scale"
// If you want to use an object instead of requesting a file:
import geographyObject from "/path/to/world-50m.json"

const colorScale = scaleLinear()
  .domain([0, 100000000, 1338612970]) // Max is based on China
  .range(["#FFF176", "#FFC107", "#E65100"])

class ChoroplethMap extends Component {
  render() {
    return (
      <div>
        <ComposableMap style={{ width: "100%" }}>
          <ZoomableGroup>
            <Geographies geography={ "/path/to/world-50m.json or geography object" } disableOptimization> // if you are using the object, then geography={geographyObject}
              {(geographies, projection) => geographies.map((geography, i) => (
                <Geography
                  key={ `geography-${i}` }
                  cacheId={ `geography-${i}` }
                  geography={ geography }
                  projection={ projection }
                  style={{
                    default: {
                      fill: colorScale(geography.properties.pop_est),
                      stroke: "#FFF",
                      strokeWidth: 0.5,
                      outline: "none",
                    },
                  }}
                />
              ))}
            </Geographies>
          </ZoomableGroup>
        </ComposableMap>
      </div>
    )
  }
}

export default ChoroplethMap
Custom TopoJSON via geography

If you want to transform your own TopoJSON maps with topojson-client, you can use geography prop to inject your own array of paths into react-simple-maps.

import React, { Component } from "react"
import { get } from "axios"
import { feature } from "topojson-client"

class CustomMap extends Component {
  contructor() {
    super()
    this.state = {
      geographyPaths: [],
    }
    this.loadPaths = this.loadPaths.bind(this)
  }
  componentDidMount() {
    this.loadPaths()
  }
  loadPaths() {
    get("/path/to/world-topojson.json")
      .then(res => {
        if (res.status !== 200) return
        const world = res.data
        const geographyPaths = feature(
          world,
          world.objects[Object.keys(world.objects)[0]]
        ).features
        this.setState({ geographyPaths })
      })
  }
  render() {
    return (
      ...
      <Geographies geography={this.state.geographyPaths} disableOptimization>
        ...
      </Geographies>
      ...
    )
  }

Check out the custom-json-geographyPaths example to see how to do this.

<Geography />

The <Geography /> component represents each shape converted with topojson. The component can be used to assign events to individual shapes on the map, and to specify their hover, focus and click behavior.

Props
Property Type Default
cacheId Number/String null
precision Number 0.1
round Boolean false
geography Object *see examples below
tabable Boolean true
style Object *see examples below
Styling

There are no default styles assigned to the <Geography /> component. Since the geography paths have to be optimized in order to allow for decent performance, the styles have to be handled by the <Geography /> component internally. The style prop is an object that defines three states for each path.

...
<Geography style={{
  default: { fill: "#666" },
  hover:   { fill: "#999" },
  pressed: { fill: "#000" },
}}/>
...
Geography events and accessing geography data in events
...
handleClick(geography, evt) {
  console.log("Geography data: ", geography)
}
...
<Geographies geography={ "/path/to/your/topojson-map-file.json" }>
  {(geographies, projection) => geographies.map((geography, i) => (
    <Geography
      key={ i }
      geography={ geography }
      projection={ projection }
      onClick={this.handleClick}
    />
  ))}
</Geographies>
...

Currently supported events are onMouseEnter, onMouseLeave, onMouseDown, onMouseUp, onClick, onMouseMove, onFocus, onBlur.

<Markers />

<Markers /> is a simple wrapper component for the individual markers.

<Marker />

The <Marker /> component represents each marker and uses coordinates to position the marker on the map. It does not make any assumptions about what your marker looks like, so you have to specify yourself what shape it should have. See the example below for how to make the recommended circular marker. The component can be used to assign events to individual markers on the map, and to specify the hover, focus and click behavior. You can also choose to preserve the markers aspect/size when in a <ZoomableGroup /> via the preserveMarkerAspect prop.

Props
Property Type Default
marker Object *see below examples
tabable Boolean true
style Object *see below examples
preserveMarkerAspect Boolean true
Marker location

Marker data is added to the marker prop and should contain the coordinates of the marker.

<Markers>
  <Marker marker={{ coordinates: [ 8.5, 47.3 ] }}>
    <circle cx={ 0 } cy={ 0 } r={ 10 } />
  </Marker>
</Markers>
Styling and shape

There are no styles assigned to the style prop, and the marker does not have a shape by default.

...
<Marker
  marker={{ coordinates: [ 8.5, 47.3 ] }}
  style={{
    default: { fill: "#666" },
    hover:   { fill: "#999" },
    pressed: { fill: "#000" },
  }
}>
  <circle cx={ 0 } cy={ 0 } r={ 10 } />
</Marker>
...
Marker events and passing marker data to marker events

In order to allow easy access to marker data when handling events, pass the marker data to the marker prop. Below is an example of how to iterate through markers.

...
handleClick(marker, evt) {
  console.log("Marker data: ", marker)
}
...
<Markers>
  { markers.map((marker, i) => (
    <Marker
      key={ i }
      marker={ marker }
      onClick={ this.handleClick }
    />
  ))}
</Markers>
...

Currently supported events are onMouseEnter, onMouseLeave, onMouseDown, onMouseUp, onClick, onMouseMove, onFocus, onBlur.

<Annotations />

<Annotations /> is a simple wrapper component for the individual annotations.

<Annotation />

<Annotation /> components can be used to add textual annotations. To position an annotation you have to specify the coordinates of the subject of the annotation, and then pass in numbers for dx and dy to specify the offset of the annotation itself.

Props
Property Type Default
subject Array [0,0]
dx Number 30
dy Number 30
zoom Number 1
stroke String "#000000"
strokeWidth Number 1
style Object {}
markerEnd String "none"
curve Number 0
Example annotation

The following example shows how to add a sample annotation for the city of Zurich on a world map.

...
<Annotation dx={ -30 } dy={ 30 } subject={ [ 8.5, 47.3 ] } strokeWidth={ 1 }>
  <text>
    { "Zurich" }
  </text>
</Annotation>
...

You can also use the <Annotations /> component to iterate over annotations.

...
<Annotations>
  {
    annotations.map((annotation, i) => (
      <Annotation
        key={i}
        dx={ -30 }
        dy={ 30 }
        subject={ annotation.coordinates }
        strokeWidth={ 1 }
        >
        <text>
          { annotation.label }
        </text>
      </Annotation>
    ))
  }
</Annotations>
...
Annotations with a curved connector

The following example shows how to add an annotation with a curved connector for the city of Zurich on a world map. The curve prop can take either a positive number (e.g. 0.5), or a negative number (e.g. -0.5) to create connectors with varying curve intensity. The default value of 0 will connect the annotation through a straight line with no curve.

...
<Annotation
  dx={ -30 }
  dy={ 30 }
  subject={ [ 8.5, 47.3 ] }
  strokeWidth={ 1 }
  curve={0.5}
  >
  <text>
    { "Zurich" }
  </text>
</Annotation>
...
Annotations with an arrow connector

To make the connector an arrow, you can pass a custom SVG marker id to the markerEnd prop of the <Annotation /> component.

...
<Annotation
  dx={ -30 }
  dy={ 30 }
  subject={ [ 8.5, 47.3 ] }
  stroke="#000"
  strokeWidth={ 1 }
  curve={0.5}
  markerEnd="url(#custom-arrow)"
  >
  <defs>
   <marker
     id="custom-arrow"
     markerWidth={10}
     markerHeight={10}
     refX={7}
     refY={5}
     orient="auto"
     markerUnits="userSpaceOnUse"
     >
     <path
       d="M1,1 L7,5 L1,9"
       fill="none"
       stroke="#000"
       strokeWidth={1}
     />
   </marker>
  </defs>
  <text>
    { "Zurich" }
  </text>
</Annotation>
...

<Graticule />

The <Graticule /> component can be used to add a graticule to the map. Note that you can place the graticule before (behind) or after (on top of) the other elements.

Props
Property Type Default
step Array [10,10]
round Boolean true
precision Nmber 0.1
outline Boolean true
stroke String "#DDDDDD"
fill String "transparent"
style Object { pointerEvents: "none" }
disableOptimization Boolean true
Globe Boolean false

<Lines />

In general <Lines /> and <Line /> components work the same way as <Markers /> and <Marker /> components, with a slight change in it's API.

<Lines /> is a simple wrapper component for the individual line.

<Line />

The <Line /> component represents each line and uses two coordinates (start and end) to position the line on the map. By default a straight line is rendered, so you have to specify yourself what shape it should have. See the example below for how to make the recommended curved line. The component can be used to assign events to individual lines on the map, and to specify the hover, focus and click behavior. You can also choose to preserve the lines aspect/size when in a <ZoomableGroup /> via the preserveMarkerAspect prop.

Props
Property Type Default
line Object *see below examples
tabable Boolean true
style Object *see below examples
preserveMarkerAspect Boolean true
buildPath Function *see below examples
Line location

Line data is added to the line prop and should contain the coordinates of the line.

<Lines>
  <Line
    line={{
      coordinates: {
        start: [0, 0],
        end: [-99.1, 19.4]
      }
    }}
  />
</Lines>
Styling and shape

There are no styles assigned to the style prop.

...
<Line
  line={{
      coordinates: {
        start: [0, 0],
        end: [-99.1, 19.4]
      }
    }}
  style={{
    default: { stroke: "#666" },
    hover:   { stroke: "#999" },
    pressed: { stroke: "#000" },
  }}
/>
...
Shaping the line

By default the line will be drawn as a straight <path />, if you wish to curve the line in a custom way you need to define a build function. This build function receives the start and end coordinates with the map projection already applied. The third argument corresponds to the line prop provided to the <Line /> component. The returned value will be applied to the resulting <path /> as the d property.

If you wish to know more about what you can achieve with the buildPath prop, checkout MDN's Path documentation.

...
// This funtion returns a curve command that builds a quadratic curve.
// And depending on the line's curveStyle property it curves in one direction or the other.
buildCurves(start, end, line) {
  const x0 = start[0];
  const x1 = end[0];
  const y0 = start[1];
  const y1 = end[1];
  const curve = {
    forceUp: `${x1} ${y0}`,
    forceDown: `${x0} ${y1}`
  }[line.curveStyle];

  return `M ${start.join(' ')} Q ${curve} ${end.join(' ')}`;
}
...
<Line
  line={{
      coordinates: {
        start: [0, 0],
        end: [-99.1, 19.4]
      }
    }}
  buildPath={this.buildCurves}
/>
Line events and passing line data to line events

In order to allow easy access to line data when handling events, pass the line data to the line prop. Below is an example of how to iterate through lines.

...
handleClick(line, evt) {
  console.log("Line data: ", line)
}
...
<Lines>
  { lines.map((line, i) => (
    <Line
      key={ i }
      line={ line }
      onClick={ this.handleClick }
    />
  ))}
</Lines>
...

Currently supported events are onMouseEnter, onMouseLeave, onMouseDown, onMouseUp, onClick, onMouseMove, onFocus, onBlur.

If you wish to see a real code example check it out here. Otherwise go check it out live at trase.earth.

License

MIT licensed. Copyright (c) Richard Zimerman 2017. See LICENSE.md for more details.