d3-geo

What is d3-geo?

The d3-geo package is part of the D3 (Data-Driven Documents) JavaScript library that focuses on geographical projections, transformations, and shapes. It allows for the creation of maps, the manipulation of geographic data, and the rendering of geographic shapes in web applications. The package provides a comprehensive set of tools for working with geography in the context of data visualization.

What are d3-geo's main functionalities?

Creating a Map Projection

This feature allows you to create a map projection, which is a method for representing the surface of the Earth on a flat surface. The example code demonstrates how to create an Albers USA projection, which is commonly used for maps of the United States.

const projection = d3.geoAlbersUsa();

Generating a Path from GeoJSON

This feature enables the generation of SVG path data from GeoJSON objects using a specified projection. The example code shows how to create a path generator with the Albers USA projection, which can then be used to render geographic features from GeoJSON data.

const path = d3.geoPath().projection(d3.geoAlbersUsa());

Computing Geodesic Distances

This feature allows for the computation of the spherical distance between two points specified by longitude and latitude. The example code calculates the distance between two geographic points, which can be useful for various geographic analyses.

const distance = d3.geoDistance([lon1, lat1], [lon2, lat2]);

Other packages similar to d3-geo

topojson

TopoJSON is an extension of GeoJSON that encodes topology. While d3-geo focuses on geographic projections and rendering, TopoJSON provides tools for encoding and simplifying geographic data, making it complementary to d3-geo for efficient transmission of geographic data.

leaflet

Leaflet is a leading open-source JavaScript library for mobile-friendly interactive maps. Unlike d3-geo, which is primarily focused on data visualization and projections, Leaflet is geared towards providing a full-fledged mapping solution with features like tile layering, user interactions, and plugins for extended functionalities.

README

d3-geo

This module uses spherical GeoJSON to represent geographic features in JavaScript. D3 supports a wide variety of common and unusual map projections. And because D3 uses spherical geometry to represent data, you can apply any aspect to any projection by rotating geometry.

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