2.2 Vector data:

Warning: In R a vector a classwith type.

Geographic vector data model is base in points located with a CRS.

Examples: center of London, a bus stop, a tree in a park, a pylon, etc ..

Then we can link this points to represent more complex object (roads, administrative boundary)

Source: Gecompx. Illustration of vector (point) data in which location of London (the red X) is represented with reference to an origin (the blue circle). The left plot represents a geographic CRS with an origin at 0° longitude and latitude. The right plot represents a projected CRS with an origin located in the sea west of the South West Peninsula.Source: Gecompx. Illustration of vector (point) data in which location of London (the red X) is represented with reference to an origin (the blue circle). The left plot represents a geographic CRS with an origin at 0° longitude and latitude. The right plot represents a projected CRS with an origin located in the sea west of the South West Peninsula.

Figure 2.1: Source: Gecompx. Illustration of vector (point) data in which location of London (the red X) is represented with reference to an origin (the blue circle). The left plot represents a geographic CRS with an origin at 0° longitude and latitude. The right plot represents a projected CRS with an origin located in the sea west of the South West Peninsula.

sf provides classes for this data types and interfaces to important low level libraries:

  • GDAL: reading, writing and manipulation data formats

  • PROJ: coordinate system transformations

  • GEOS: planar geometry engine (buffer, centroid, etc)

  • S2: a spherical geometry engine