"["(x, i, ...) "["(x, i, ...) <- value"tess")."owin").
"owin") or NULL.
"tess").
"tess", see tess)
is effectively a list of tiles (spatial regions) that cover a spatial region.
The subset operator [.tess extracts some
of these tiles and forms a new tessellation, which of course covers a
smaller region than the original. For [.tess only, the subset index can also be a window
(object of class "owin"). The tessellation x
is then intersected with the window.
The replacement operator changes the selected tiles. The replacement
value may be either NULL (which causes the selected tiles
to be removed from x) or a list of the same length as
the selected subset. The entries of value may be windows
(objects of class "owin") or NULL to indicate that the
corresponding tile should be deleted.
Generally it does not make sense to replace a tile in a tessellation with a completely different tile, because the tiles are expected to fit together. However this facility is sometimes useful for making small adjustments to polygonal tiles.
tess, tiles, intersect.tess.
A <- tess(xgrid=0:4, ygrid=0:3)
B <- A[c(1, 3, 7)]
E <- A[-1]
A[c(2, 5, 11)] <- NULL
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