list with numeric items left, right, top, bottom, and character items t0 and t1, or a subset thereof, see examples
iextent
list with length-two integer items named x, y, and t, defining the lower and upper boundaries as integer coordinates, see examples
snap
one of ‘near’, ‘in’, or ‘out’; ignored if using iextent
Details
The new extent can be specified by spatial coordinates and datetime values (using the extent argument), or as zero-based integer indexes (using the iextent argument). In the former case, extent expects a list with numeric items left, right, top, bottom, t0, and t1, or a subset thereof. In the latter case, 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.
Notice that it is possible to crop only selected boundaries (e.g., only the right boundary) as missing boundaries in the extent or NA / NULL values in the iextent arguments are considered as “no change”. It is, however, not possible to mix arguments extent and iextent.
If extent is given, the snap argument can be used to define what happens if the new boundary falls within a data cube cell.
Note
This function returns a proxy object, i.e., it will not start any computations besides deriving the shape of the result.
Examples
# create image collection from example Landsat data only # if not already done in other examplesif (!file.exists(file.path(tempdir(), "L8.db"))) { L8_files <-list.files(system.file("L8NY18", package ="gdalcubes"),".TIF", recursive =TRUE, full.names =TRUE)create_image_collection(L8_files, "L8_L1TP", file.path(tempdir(), "L8.db"), quiet =TRUE) }L8.col =image_collection(file.path(tempdir(), "L8.db"))v =cube_view(extent=list(left=388941.2, right=766552.4, bottom=4345299, top=4744931, t0="2018-01", t1="2018-12"),srs="EPSG:32618", nx =497, ny=526, dt="P3M", aggregation ="median")L8.cube =raster_cube(L8.col, v, mask=image_mask("BQA", bits=4, values=16))L8.rgb =select_bands(L8.cube, c("B02", "B03", "B04"))# crop by integer indexesL8.cropped =crop(L8.rgb, iextent =list(x=c(0,400), y=c(0,400), t=c(1,1)))# crop by spatiotemporal coordinatesL8.cropped =crop(L8.rgb, extent =list(left=388941.2, right=766552.4, bottom=4345299, top=4744931, t0="2018-01", t1="2018-06"), snap ="in")L8.cropped
A data cube proxy object
Dimensions:
low high count pixel_size chunk_size
t 2018-01-01 2018-06-30 2 P3M 1
y 4345299 4744931 526 759.756653992395 384
x 388941.2 766552.4 497 759.781086519115 384
Bands:
name offset scale nodata unit
1 B02 0 1 NaN
2 B03 0 1 NaN
3 B04 0 1 NaN
A data cube proxy object
Dimensions:
low high count pixel_size chunk_size
t 2018-01-01 2018-09-30 3 P3M 1
y 4345299 4744931 526 759.756653992395 384
x 388941.2 766552.4 497 759.781086519115 384
Bands:
name offset scale nodata unit
1 B02 0 1 NaN
2 B03 0 1 NaN
3 B04 0 1 NaN
plot(L8.cropped, rgb =3:1, zlim=c(5000,10000))
Source Code
# cropCrop data cube extent by space and/or time```{r include=FALSE}library(gdalcubes)```## DescriptionCreate a proxy data cube, which crops a data cube by a spatial and/or temporal extent.## Usage```rcrop(cube, extent =NULL, iextent =NULL, snap ="near")```## Arguments| Argument | Description ||:------------|:----------------------------------|| cube | source data cube || extent | list with numeric items left, right, top, bottom, and character items t0 and t1, or a subset thereof, see examples || iextent | list with length-two integer items named x, y, and t, defining the lower and upper boundaries as integer coordinates, see examples || snap | one of 'near', 'in', or 'out'; ignored if using `iextent` |## DetailsThe new extent can be specified by spatial coordinates and datetime values (using the `extent` argument), or as zero-based integer indexes (using the `iextent` argument).In the former case, `extent` expects a list with numeric items left, right, top, bottom, t0, and t1, or a subset thereof. In the latter case,`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.Notice that it is possible to crop only selected boundaries (e.g., only the right boundary) as missing boundaries in the `extent` or NA / NULL values in the `iextent` arguments are considered as "no change".It is, however, not possible to mix arguments `extent` and `iextent`.If `extent` is given, the `snap` argument can be used to define what happens if the new boundary falls within a data cube cell.## NoteThis function returns a proxy object, i.e., it will not start any computations besides deriving the shape of the result.## Examples```{r}# create image collection from example Landsat data only # if not already done in other examplesif (!file.exists(file.path(tempdir(), "L8.db"))) { L8_files <-list.files(system.file("L8NY18", package ="gdalcubes"),".TIF", recursive =TRUE, full.names =TRUE)create_image_collection(L8_files, "L8_L1TP", file.path(tempdir(), "L8.db"), quiet =TRUE) }L8.col =image_collection(file.path(tempdir(), "L8.db"))v =cube_view(extent=list(left=388941.2, right=766552.4, bottom=4345299, top=4744931, t0="2018-01", t1="2018-12"),srs="EPSG:32618", nx =497, ny=526, dt="P3M", aggregation ="median")L8.cube =raster_cube(L8.col, v, mask=image_mask("BQA", bits=4, values=16))L8.rgb =select_bands(L8.cube, c("B02", "B03", "B04"))# crop by integer indexesL8.cropped =crop(L8.rgb, iextent =list(x=c(0,400), y=c(0,400), t=c(1,1)))# crop by spatiotemporal coordinatesL8.cropped =crop(L8.rgb, extent =list(left=388941.2, right=766552.4, bottom=4345299, top=4744931, t0="2018-01", t1="2018-06"), snap ="in")L8.cropped L8.cropped =crop(L8.rgb, extent =list(left=388941.2, right=766552.4, bottom=4345299, top=4744931, t0="2018-01", t1="2018-06"), snap ="near")L8.cropped plot(L8.cropped, rgb =3:1, zlim=c(5000,10000))```
