Create Polygons of Equipotential — equipotential • potential

This function creates polygons of equipotential from a regular grid of potential points.

equipotential(x, var, nclass = 8, breaks, mask, buffer, xcoords, ycoords)

Arguments

x: an sf object of regularly spaced points.
var: name of the variable to use in x.
nclass: a number of class.
breaks: a vector of break values.
mask: an sf object of polygons or multipolygons. mask is used to clip polygons of contours equipotential.
buffer: if set, a buffer is added to the mask in order to reach more precisely the number of breaks. The buffer is defined in x units.
xcoords: not used.
ycoords: not used.

Value

The output is an sf object (POLYGONS). The data frame contains four fields: id (id of each polygon), min and max (minimum and maximum breaks of the polygon) and center (central values of classes).

Examples

library(sf)
y <- create_grid(x = n3_poly, res = 200000)
d <- create_matrix(n3_pt, y)
pot <- potential(
  x = n3_pt, y = y, d = d, var = "POP19",
  fun = "e", span = 200000, beta = 2
)
y$OUTPUT <- pot
equipot <- equipotential(y, var = "OUTPUT", mask = n3_poly)
plot(equipot["center"], pal = hcl.colors(nrow(equipot), "cividis"))