Thin point dataset to have 1 observation per raster cell

This function thins a dataset so that only one observation per cell is retained.

Usage

thin_by_cell(data, raster, coords = NULL, drop_na = TRUE, agg_fact = NULL)

Arguments

data

An sf::sf data frame, or a data frame with coordinate variables. These can be defined in coords, unless they have standard names (see details below).

raster

A terra::SpatRaster or stars object that defined the grid

coords

a vector of length two giving the names of the "x" and "y" coordinates, as found in data. If left to NULL, the function will try to guess the columns based on standard names c("x", "y"), c("X","Y"), c("longitude", "latitude"), or c("lon", "lat")

drop_na

boolean on whether locations that are NA in the raster should be dropped.

agg_fact

positive integer. Aggregation factor expressed as number of cells in each direction (horizontally and vertically). Or two integers (horizontal and vertical aggregation factor) or three integers (when also aggregating over layers). Defaults to NULL, which implies no aggregation (i.e. thinning is done on the grid of raster)

Value

An object of class sf::sf or data.frame, the same as "data".

Details

Further thinning can be achieved by aggregating cells in the raster before thinning, as achieved by setting agg_fact > 1 (aggregation works in a manner equivalent to terra::aggregate()). Note that if data is an sf object, the function will transform the coordinates to the same projection as the raster (recommended); if data is a data.frame, it is up to the user to ensure that the coordinates are in the correct units.