Whole grain buffers

Ensure a raster extent aligns to a clean divisor.

buffer_extent(e1, e2)

Arguments

e1

input extent
e2

grain size

Details

This function is used to generate extents that have tidy boundaries, i.e. extents that align to a clean whole number like "10000".

(We can't use the S4 group generic because raster has set that specifically for use with '+' and '-'.)

Examples

library(raster)
#> Loading required package: sp
buffer_extent(extent(0.1, 2.2, 0, 3), 2)
#> class      : Extent 
#> xmin       : 0 
#> xmax       : 4 
#> ymin       : 0 
#> ymax       : 4 

p <- par(xpd = NA)
plot(lux)
plot(extent(lux), lty = 2, add = TRUE, col = "grey")
plot(buffer_extent(lux, 0.1), add = TRUE)
abline(v = c(5.7, 6.6), h = c(49.4, 50.2))
title("boundaries on clean alignment to 0.1")
par(p)