sf (version 1.0-18)

interpolate_aw: Areal-weighted interpolation of polygon data

Description

Areal-weighted interpolation of polygon data

Usage

st_interpolate_aw(x, to, extensive, ...)
# S3 method for sf
st_interpolate_aw(x, to, extensive, ..., keep_NA = FALSE, na.rm = FALSE)

Arguments

x

object of class sf, for which we want to aggregate attributes

to

object of class sf or sfc, with the target geometries

extensive

logical; if TRUE, the attribute variables are assumed to be spatially extensive (like population) and the sum is preserved, otherwise, spatially intensive (like population density) and the mean is preserved.

...

ignored

keep_NA

logical; if TRUE, return all features in to, if FALSE return only those with non-NA values (but with row.names the index corresponding to the feature in to)

na.rm

logical; if TRUE remove features with NA attributes from x before interpolating

Details

if extensive is TRUE and na.rm is set to TRUE, geometries with NA are effectively treated as having zero attribute values.

Examples

nc = st_read(system.file("shape/nc.shp", package="sf"))
g = st_make_grid(nc, n = c(10, 5))
a1 = st_interpolate_aw(nc["BIR74"], g, extensive = FALSE)
sum(a1$BIR74) / sum(nc$BIR74) # not close to one: property is assumed spatially intensive
a2 = st_interpolate_aw(nc["BIR74"], g, extensive = TRUE)
# verify mass preservation (pycnophylactic) property:
sum(a2$BIR74) / sum(nc$BIR74)
a1$intensive = a1$BIR74
a1$extensive = a2$BIR74
plot(a1[c("intensive", "extensive")], key.pos = 4)