Latitude is the horizontal geographic coordinate that measures distance north or south of the equator. Together with longitude, it locates a point on Earth. section 13.1.1
When mapping data with D3, latitude is used as part of a coordinate pair:
- Store a location as [longitude, latitude], such as a city’s birth coordinates. section 13.2.4
- Pass the pair to a projection, which converts the geographic position into SVG x and y coordinates. section 13.7
Plotting birth cities
A Nobel laureate map can retain each city’s latitude and longitude, pass them through a D3 projection, and draw a circle at the returned position. Circle radius can then represent how many laureates were born there. section 13.2.4
const projection = d3.geoEqualEarth(); [x, y] = projection([longitude, latitude]);
This compact pattern shows latitude in its practical role: the second value in a [longitude, latitude] pair sent to a D3 projection. section 13.2.4
