isopoly {SpatialPosition} | R Documentation |
Create Spatial Polygons Contours from a Raster
Description
This function creates spatial polygons of contours from a raster.
Usage
isopoly(
x,
nclass = 8,
breaks,
mask,
xcoords = "COORDX",
ycoords = "COORDY",
var = "OUTPUT",
returnclass = "sp"
)
Arguments
x |
sf POINT data.frame; must contain X, Y and OUTPUT fields. |
nclass |
numeric; a number of class. |
breaks |
numeric; a vector of break values. |
mask |
sf POLYGON data.frame; mask used to clip contour shapes. |
xcoords |
character; name of the X coordinates field in x. |
ycoords |
character; name of the Y coordinates field in x. |
var |
character; name of the OUTPUT field in x. |
returnclass |
"sp" or "sf"; class of the returned object. |
Value
The output is an sf POLYGON data.frame. The data frame contains four fields: id (id of each polygon), min and max (minimum and maximum breaks of the polygon), center (central values of classes).
See Also
Examples
data(hospital)
# Compute Stewart potentials
mystewart <- stewart(knownpts = hospital, varname = "capacity",
typefct = "exponential", span = 1000, beta = 3,
mask = paris, returnclass = "sf")
# Create contour
contourpoly <- isopoly(x = mystewart,
nclass = 6,
mask = paris, returnclass = "sf")
library(sf)
plot(st_geometry(contourpoly))
if(require(cartography)){
# Created breaks
bks <- sort(unique(c(contourpoly$min, contourpoly$max)))
opar <- par(mar = c(0,0,1.2,0))
# Display the map
choroLayer(x = contourpoly,
var = "center", legend.pos = "topleft",
breaks = bks, border = "grey90",
lwd = 0.2,
legend.title.txt = "Potential number\nof beds in the\nneighbourhood",
legend.values.rnd = 0)
plot(st_geometry(paris), add = TRUE)
propSymbolsLayer(x = hospital, var = "capacity",
legend.pos = "right",
legend.title.txt = "Number of beds",
col = "#ff000020")
layoutLayer(title = "Global Accessibility to Public Hospitals",
sources = "", author = "")
par(opar)
}
[Package SpatialPosition version 2.1.2 Index]