Get Tile

Get specific tile(s) from the data based on a tile* object. Indexing via i and j params is used to select the tile(s) to get, in a manner similar to [ extraction of bounds from tile* objects.

All params are usable with any method except when otherwise stated.

This generic handles data/tile* object interactions. For simple selection of data based on a set of bounds, see the low-level generic getBoundedData().

The character method only works for filetypes readable by {terra}.

New x data types should automatically work with this generic as long as a getBoundedData() method is created for it. A specific getTile() method is only needed if additional params/operations should be performed before the tile selection, (for example layer selection with raster data).

Usage

# S4 method for class 'token,tilePlan'
getTile(x, tiles, ...)

# S4 method for class 'ANY,tilePlan'
getTile(x, tiles, i = NULL, j, pad = NULL, sel_params = list(), ...)

# S4 method for class 'character,tilePlan'
getTile(x, tiles, prefer = NULL, ext = NULL, ...)

# S4 method for class 'SpatRaster,tilePlan'
getTile(x, tiles, lyr = NULL, extend = FALSE, fill = NA, ...)

# S4 method for class 'SpatRaster,pointTilePlan'
getTile(x, tiles, lyr = NULL, extend = FALSE, fill = NA, ...)

# S4 method for class 'ANY,tileGroup'
getTile(x, tiles, i, j, ...)

# S4 method for class 'ANY,tileIterator'
getTile(x, tiles, advance = TRUE, ...)

Arguments

x

data

tiles

tile* object

...

additional params to pass to [ tilePlan indexing

i

ANY except tileIterator tile vector index or row index if j is also provided

j

ANY except tileIterator tile col index

pad

(optional) additional padding to apply before tile retrieval. Useful for temporarily increasing padding without affecting tile* object.

sel_params

list of named params to pass to the tile [ selection call. Rarely needed; covers internal [ options such as expand_grid.

prefer

character filepath only character. Hint for file reading ("raster" or "vector"). If provided, skips automatic type detection.

ext

SpatRaster or raster filepath (character) only numeric or SpatExtent (optional) Set an extent before extracting tiles from raster.

lyr

SpatRaster only if provided, which layers/channels to include

extend

pixelTilePlan only logical (default = FALSE). Whether to extend tile data to reach expected tile dimensions

fill

pixelTilePlan only numeric. if extend = TRUE, what value to fill with

advance

tileIterator only logical (default = TRUE). Whether to advance the iterator.

Value

list of tile data

See also

getBoundedData()

Other tile processing: getBoundedData(), tileApply(), tileApply-group, tileApply-iterator, tileApply-plan

Examples

f <- system.file("ex/elev.tif", package = "terra")
r <- terra::rast(f)
tp <- tilePlan("pixel")
tp$pxdims <- dim(r)[1:2]
tp$nrows <- 10
tp$ncols <- 10

# get tiles from specific array grid indices.
tile_list <- getTile(f, tp, i = 3, j = 5)
force(tile_list)
#> [[1]]
#> class       : SpatRaster 
#> size        : 10, 10, 1  (nrow, ncol, nlyr)
#> resolution  : 0.008333333, 0.008333333  (x, y)
#> extent      : 6.075, 6.158333, 49.94167, 50.025  (xmin, xmax, ymin, ymax)
#> coord. ref. : lon/lat WGS 84 (EPSG:4326) 
#> source(s)   : memory
#> varname     : elev 
#> name        : elevation 
#> min value   :       346 
#> max value   :       520 
#> 
plot(tile_list[[1]])


# get tiles via iteration
iter <- tileIterator(tp, batch_size = 3)
b1 <- getTile(r, iter) # get first batch of 3...
b2 <- getTile(r, iter) # get second batch of 3...