Median centre of points

The median of the x coordinates and the median of the y coordinates (the mean of the two middle values for an even number of points). It depends on the orientation of the axes: rotating the points does not rotate it. webpt() gives the rotation-invariant centre of minimum distance.

Usage

cgmedn(x, y = NULL, lonlat = FALSE)

Arguments

x, y

The points: x and y numeric vectors of equal length; or x a matrix or data frame with columns named x and y (or X and Y, as sf::st_coordinates() names them, or lon and lat with lonlat = TRUE) and y NULL; or x an sf or sfc object of POINT geometries, whose coordinate reference system must agree with lonlat. An unnamed two-column matrix is read as x then y; other columns are never taken by position. Vectors given separately (x, y, and w or t where a function takes them) are matched by name when every one is named and no name repeats, as elsewhere in the package; otherwise by position. No missing or infinite values.

lonlat

FALSE (the default) when x and y are planar coordinates in one length unit; TRUE when they are longitude and latitude in degrees, which are then projected to metres by eqproj() about their own centre, and centres are returned in degrees. It is never guessed.

Value

A named numeric vector c(x, y), in degrees when lonlat = TRUE (the medians are taken of the projected coordinates).

References

Neft, D. S. (1966). Statistical Analysis for Areal Distributions. Regional Science Research Institute, Philadelphia.

Examples

cgmedn(c(1, 2, 3, 10), c(5, 1, 2, 2))
#>   x   y 
#> 2.5 2.0