Virtual grid modification — vcrop • vaster

To modify a grid is to align an extent to the grid origin. Modification includes to reduce or extend the area covered, in either dimension. This implies a new extent, snapped to the grain of the origin grid and a new size (dimension in x,y).

vcrop(x, dimension, extent = NULL, ..., snap = "out")

Arguments

x: extent of candidate grid (vector of xmin,xmax,ymin,ymax)
dimension: integer ncol, nrow
extent: numeric extent xmin,xmax,ymin,ymax
...: ignored
snap: one of "out" (default), "near", or "in"

Details

This works for any grid, the input extent can be within the original, an extension of the original, or completely non-intersecting the original grid.

Examples

## any arbitrary extent
x <- c(sort(runif(2, -180, 180)), sort(runif(2, -90, 90)))
print(x)
#> [1]  83.83752  98.10774 -58.51069  67.42812
vcrop(x,  c(360, 180), c(-180, 180, -90, 90))
#> $extent
#> [1]  83  99 -59  68
#> 
#> $dimension
#> [1]  16 127
#>