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65 lines
3 KiB
R
65 lines
3 KiB
R
% Generated by roxygen2: do not edit by hand
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% Please edit documentation in R/crop.R
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\name{crop}
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\alias{crop}
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\title{Crop data cube extent by space and/or time}
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\usage{
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crop(cube, extent = NULL, iextent = NULL, snap = "near")
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}
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\arguments{
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\item{cube}{source data cube}
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\item{extent}{list with numeric items left, right, top, bottom, and character items t0 and t1, or a subset thereof, see examples}
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\item{iextent}{list with length-two integer items named x, y, and t, defining the lower and upper boundaries as integer coordinates, see examples}
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\item{snap}{one of 'near', 'in', or 'out'; ignored if using \code{iextent}}
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}
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\description{
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Create a proxy data cube, which crops a data cube by a spatial and/or temporal extent.
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}
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\details{
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The new extent can be specified by spatial coordinates and datetime values (using the \code{extent} argument), or as zero-based integer indexes (using the \code{iextent} argument).
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In the former case, \code{extent} expects a list with numeric items left, right, top, bottom, t0, and t1, or a subset thereof. In the latter case,
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\code{iextent} is expected as a list with length-two integer vectors x, y, and t as items, defining the lower and upper cell indexes per dimension.
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Notice that it is possible to crop only selected boundaries (e.g., only the right boundary) as missing boundaries in the \code{extent} or NA / NULL values in the \code{iextent} arguments are considered as "no change".
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It is, however, not possible to mix arguments \code{extent} and \code{iextent}.
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If \code{extent} is given, the \code{snap} argument can be used to define what happens if the new boundary falls within a data cube cell.
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}
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\note{
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This function returns a proxy object, i.e., it will not start any computations besides deriving the shape of the result.
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}
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\examples{
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# create image collection from example Landsat data only
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# if not already done in other examples
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if (!file.exists(file.path(tempdir(), "L8.db"))) {
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L8_files <- list.files(system.file("L8NY18", package = "gdalcubes"),
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".TIF", recursive = TRUE, full.names = TRUE)
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create_image_collection(L8_files, "L8_L1TP", file.path(tempdir(), "L8.db"), quiet = TRUE)
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}
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L8.col = image_collection(file.path(tempdir(), "L8.db"))
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v = cube_view(extent=list(left=388941.2, right=766552.4,
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bottom=4345299, top=4744931, t0="2018-01", t1="2018-12"),
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srs="EPSG:32618", nx = 497, ny=526, dt="P3M", aggregation = "median")
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L8.cube = raster_cube(L8.col, v, mask=image_mask("BQA", bits=4, values=16))
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L8.rgb = select_bands(L8.cube, c("B02", "B03", "B04"))
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# crop by integer indexes
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L8.cropped = crop(L8.rgb, iextent = list(x=c(0,400), y=c(0,400), t=c(1,1)))
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# crop by spatiotemporal coordinates
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L8.cropped = crop(L8.rgb, extent = list(left=388941.2, right=766552.4,
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bottom=4345299, top=4744931, t0="2018-01", t1="2018-06"), snap = "in")
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L8.cropped
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L8.cropped = crop(L8.rgb, extent = list(left=388941.2, right=766552.4,
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bottom=4345299, top=4744931, t0="2018-01", t1="2018-06"), snap = "near")
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L8.cropped
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\donttest{
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plot(L8.cropped, rgb = 3:1, zlim=c(5000,10000))
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}
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}
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