| Title: | Tools for Raster Grid Logic |
|---|---|
| Description: | Provides raster grid logic, the grid operations that don't require access to materialized data, i.e. most of them. Grids are arrays with dimension and extent, and many operations are functions of just the dimension 'nrows', 'ncols' or a combination of the dimension and the extent 'xmin', 'xmax', 'ymin', 'ymax'. Here we provide direct access to this logic without need for connection to any materialized data or formats. Grid logic includes functions that relate the cell index to row and column, or row and column to cell index, row, column or cell index to position. Cell index, and row,column posiiton exist independently of any other use of a raster grid. |
| Authors: | Michael Sumner [aut, cre] |
| Maintainer: | Michael Sumner <[email protected]> |
| License: | MIT + file LICENSE |
| Version: | 0.0.2.9004 |
| Built: | 2024-10-31 22:10:57 UTC |
| Source: | https://github.com/hypertidy/vaster |
Functions 'bottom left', 'top left', 'bottom right', and 'top right' named by their initials, provide very low level relative positional structures for use in raster logic. These are used to traverse the divide left by area-based rasters which are inherently a discrete value across a finite element. If we want that element as part of a continuous surface we need to find local relative values for its corners. Used in quadmesh and anglr packages, and useful for calculating neighbourhood values.
bl(x) tl(x) br(x) tr(x) la(x) ta(x) ra(x) ba(x) image0(x, ...) image1(x, ...) text0(x, ...)bl(x) tl(x) br(x) tr(x) la(x) ta(x) ra(x) ba(x) image0(x, ...) image1(x, ...) text0(x, ...)
x |
matrix |
... |
arguments passed to image() |
bl, tl, br, and tr originally lived in affinity
matrix, padded by one row and one column relative to input
(m <- matrix(1:12, 3)) tl(m) tr(m) bl(m) br(m) tl(br(m)) image0(tl(br(m))) text0(tl(br(m))) ## this gives neighbours in adjacent positions m <- matrix(1:12, ncol = 3, byrow = TRUE) matrix(c(t(la(m)), t(ta(m)), t(ra(m)), t(ba(m))), ncol = 4) ## this gives neighbours in all 8 adjacent and diagonal positions image(matrix(rowMeans(matrix(c(t(la(m)), t(ta(m)), t(ra(m)), t(ba(m)), t(bl(m)), t(tl(m)), t(br(m)), t(tr(m))), ncol = 8), na.rm = TRUE), 4, byrow = TRUE))(m <- matrix(1:12, 3)) tl(m) tr(m) bl(m) br(m) tl(br(m)) image0(tl(br(m))) text0(tl(br(m))) ## this gives neighbours in adjacent positions m <- matrix(1:12, ncol = 3, byrow = TRUE) matrix(c(t(la(m)), t(ta(m)), t(ra(m)), t(ba(m))), ncol = 4) ## this gives neighbours in all 8 adjacent and diagonal positions image(matrix(rowMeans(matrix(c(t(la(m)), t(ta(m)), t(ra(m)), t(ba(m)), t(bl(m)), t(tl(m)), t(br(m)), t(tr(m))), ncol = 8), na.rm = TRUE), 4, byrow = TRUE))
A crop (or extend), it snaps the input extent to the origin of the input extent (based on the dimension) #' Note that snap is modelled on the behaviour of the raster package, and is different from projwin in GDAL (WIP to illustrate).
align_extent(x, dimension, extent = NULL, snap = c("out", "near", "in"))align_extent(x, dimension, extent = NULL, snap = c("out", "near", "in"))
x |
extent |
dimension |
integer ncol, nrow |
extent |
numeric extent xmin,xmax,ymin,ymax |
snap |
out by default, may be near or in |
aligned extent
align_extent(c(4.5, 5.6, 2, 4), c(10, 5), c(0, 10, 0, 5))align_extent(c(4.5, 5.6, 2, 4), c(10, 5), c(0, 10, 0, 5))
Functions that work with cells.
cell_from_xy(dimension, extent = NULL, xy) cell_from_extent(dimension, extent = NULL, x_extent) extent_from_cell(dimension, extent = NULL, cell) rowcol_from_cell(dimension, extent = NULL, cell) xy_from_cell(dimension, extent = NULL, cell) x_from_cell(dimension, extent = NULL, cell) y_from_cell(dimension, extent = NULL, cell) col_from_cell(dimension, cell) row_from_cell(dimension, cell) cell_from_row(dimension, row) cell_from_col(dimension, col) cell_from_row_col(dimension, row, col) cell_from_rowcol_combine(dimension, row, col)cell_from_xy(dimension, extent = NULL, xy) cell_from_extent(dimension, extent = NULL, x_extent) extent_from_cell(dimension, extent = NULL, cell) rowcol_from_cell(dimension, extent = NULL, cell) xy_from_cell(dimension, extent = NULL, cell) x_from_cell(dimension, extent = NULL, cell) y_from_cell(dimension, extent = NULL, cell) col_from_cell(dimension, cell) row_from_cell(dimension, cell) cell_from_row(dimension, row) cell_from_col(dimension, col) cell_from_row_col(dimension, row, col) cell_from_rowcol_combine(dimension, row, col)
dimension |
integer ncol, nrow |
extent |
numeric extent xmin,xmax,ymin,ymax |
xy |
matrix of coordinates |
x_extent |
extent to find cells of |
cell |
cells to find extent, or row,col, or xy of |
row |
row to find cell of |
col |
column to find cell of |
The cell is indexed from the top left corner and proceeds to the right, and then down scanning by rows. The n cell is a the bottom right corner. Orientation is different to R's native matrix order, but see (WiP doc and helpers for conversion).
cell index
cells of extent
extent of cells
row,col of cells
xy from cells
x of cells
y of cells
col of cells
row of cells
cell of rows
cell of cols
cell of row,col
cell of row,col combined
cell_from_xy(c(10, 5), extent = c(0, 10, 0, 5), cbind(5, 4)) cell_from_extent(c(10, 5), c(0, 10, 0, 5), c(6, 7, 2, 3)) extent_from_cell(c(10, 5), c(0, 10, 0, 5), c(4, 5)) rowcol_from_cell(c(10, 5), c(0, 10, 0, 5), 3:5) xy_from_cell(c(10, 5), c(0, 10, 0, 5), 4:6) x_from_cell(c(10, 5), c(0, 10, 0, 5), 4:7) y_from_cell(c(10, 5), c(0, 10, 0, 5), 4:7) col_from_cell(c(10, 5), 4:7) row_from_cell(c(10, 5), 4:7) cell_from_row(c(10, 5), 4:7) cell_from_col(c(10, 5), 4:7) cell_from_row_col(c(10, 5), 1:4, 4:7) cell_from_rowcol_combine(c(10, 5), 1:4, 4:7)cell_from_xy(c(10, 5), extent = c(0, 10, 0, 5), cbind(5, 4)) cell_from_extent(c(10, 5), c(0, 10, 0, 5), c(6, 7, 2, 3)) extent_from_cell(c(10, 5), c(0, 10, 0, 5), c(4, 5)) rowcol_from_cell(c(10, 5), c(0, 10, 0, 5), 3:5) xy_from_cell(c(10, 5), c(0, 10, 0, 5), 4:6) x_from_cell(c(10, 5), c(0, 10, 0, 5), 4:7) y_from_cell(c(10, 5), c(0, 10, 0, 5), 4:7) col_from_cell(c(10, 5), 4:7) row_from_cell(c(10, 5), 4:7) cell_from_row(c(10, 5), 4:7) cell_from_col(c(10, 5), 4:7) cell_from_row_col(c(10, 5), 1:4, 4:7) cell_from_rowcol_combine(c(10, 5), 1:4, 4:7)
Functions that work with coordinates.
x_corner(dimension, extent = NULL) y_corner(dimension, extent = NULL) x_centre(dimension, extent = NULL) y_centre(dimension, extent = NULL) x_from_col(dimension, extent = NULL, col) y_from_row(dimension, extent = NULL, row) col_from_x(dimension, extent = NULL, x) row_from_y(dimension, extent = NULL, y) xy(dimension, extent = NULL)x_corner(dimension, extent = NULL) y_corner(dimension, extent = NULL) x_centre(dimension, extent = NULL) y_centre(dimension, extent = NULL) x_from_col(dimension, extent = NULL, col) y_from_row(dimension, extent = NULL, row) col_from_x(dimension, extent = NULL, x) row_from_y(dimension, extent = NULL, y) xy(dimension, extent = NULL)
dimension |
integer ncol, nrow |
extent |
numeric extent xmin,xmax,ymin,ymax |
col |
column index |
row |
row index |
x |
x coordinate |
y |
y coordinate |
x coordinate of corners
y coordinate of corners
x coordinate of centres
y coordinate of centres
x coordinate of col (centre)
y coordinate of row (centre)
col of x coordinate
y coordinate (centre) of row
xy coordinate (centre) of grid
x_corner(c(10, 5), c(0, 10, 0, 5)) y_corner(c(10, 5), c(0, 10, 0, 5)) x_centre(c(10, 5), c(0, 10, 0, 5)) y_centre(c(10, 5), c(0, 10, 0, 5)) x_from_col(c(10, 5), c(0, 10, 0, 5), 2:3) y_from_row(c(10, 5), c(0, 10, 0, 5), 2:3) col_from_x(c(10, 5), c(0, 10, 0, 5), 3.5 + 1:2) row_from_y(c(10, 5), c(0, 10, 0, 5), 2:3) xy(c(10, 5), c(0, 10, 0, 5))x_corner(c(10, 5), c(0, 10, 0, 5)) y_corner(c(10, 5), c(0, 10, 0, 5)) x_centre(c(10, 5), c(0, 10, 0, 5)) y_centre(c(10, 5), c(0, 10, 0, 5)) x_from_col(c(10, 5), c(0, 10, 0, 5), 2:3) y_from_row(c(10, 5), c(0, 10, 0, 5), 2:3) col_from_x(c(10, 5), c(0, 10, 0, 5), 3.5 + 1:2) row_from_y(c(10, 5), c(0, 10, 0, 5), 2:3) xy(c(10, 5), c(0, 10, 0, 5))
Draw an extent with two clicks
draw_extent(show = TRUE, ...)draw_extent(show = TRUE, ...)
show |
the drawn extent |
... |
arguments pass to |
Create the geotransform (see geo_transform0()) from extent and dimension.
extent_dim_to_gt(x, dimension)extent_dim_to_gt(x, dimension)
x |
extent parameters, c(xmin,xmax,ymin,ymax) |
dimension |
dimensions x,y of grid (ncol,nrow) |
The dimension is always ncol, nrow.
6-element geo_transform0()
extent_dim_to_gt(c(0, 5, 0, 10), c(5, 10))extent_dim_to_gt(c(0, 5, 0, 10), c(5, 10))
input is the output of align_extent
extent_dimension(x, dimension, extent = NULL, snap = "out")extent_dimension(x, dimension, extent = NULL, snap = "out")
x |
and aligned extent |
dimension |
dimension of parent |
extent |
of parent |
snap |
out by default, may be near or in |
dimension
extent_dimension(c(.2, .8, 1.8, 3.2), c(10, 5), c(0, 10, 0, 5))extent_dimension(c(.2, .8, 1.8, 3.2), c(10, 5), c(0, 10, 0, 5))
Get extent from index values in VRT text.
extent_vrt(x)extent_vrt(x)
x |
url or file path to VRT file |
(I can't understand XML tech so I hack the text as lines with strsplit)
#src <- "https://opentopography.s3.sdsc.edu/raster/NASADEM/NASADEM_be.vrt" #src <- "https://opentopography.s3.sdsc.edu/raster/SRTM_GL1/SRTM_GL1_srtm.vrt" #ex <- extent_vrt(src) #op <- par(mar = rep(0, 4)) #plot(range(ex[,1:2]), range(ex[,3:4]), xlab = "", ylab = "", asp = "", type = "n") #rect(ex[,1], ex[,3], ex[, 2], ex[,4]) #par(op)#src <- "https://opentopography.s3.sdsc.edu/raster/NASADEM/NASADEM_be.vrt" #src <- "https://opentopography.s3.sdsc.edu/raster/SRTM_GL1/SRTM_GL1_srtm.vrt" #ex <- extent_vrt(src) #op <- par(mar = rep(0, 4)) #plot(range(ex[,1:2]), range(ex[,3:4]), xlab = "", ylab = "", asp = "", type = "n") #rect(ex[,1], ex[,3], ex[, 2], ex[,4]) #par(op)
This function is very liberal, it simply finds unique x values and unique y values, sorts them and finds the minimum difference between the points, then checks that rounded ratio of differences to this minimum is 1.
from_xyz(xyz, digits = 5)from_xyz(xyz, digits = 5)
xyz |
set of points xy or xyz (matrix or data frame) |
digits |
argument passed to |
The points can be the full grid set, a partial set, or a superset of the grid. The resolution will simply be
the smallest actual difference found. (Zero is not possible because we sort(unique(...))).
The z-column if present is ignored.
list with elements 'dimension', 'extent'
from_xyz(vaster_long(c(10, 5), c(0, 10, 0, 5)))from_xyz(vaster_long(c(10, 5), c(0, 10, 0, 5)))
Basic function to create a geotransform as used by GDAL.
geo_transform0(px, ul, sh = c(0, 0))geo_transform0(px, ul, sh = c(0, 0))
px |
pixel resolution (XY, Y-negative) |
ul |
grid offset, top-left corner |
sh |
affine shear (XY) |
vector of parameters xmin, xres, yskew, ymax, xskew, yres
geo_world0() which uses the same parameters in a different order
geo_transform0(px = c(1, -1), ul = c(0, 0))geo_transform0(px = c(1, -1), ul = c(0, 0))
Basic function to create a 'world file' as used by various non-geo image formats
Reformat to world vector.
geo_world0(px, ul, sh = c(0, 0)) geotransform_to_world(x)geo_world0(px, ul, sh = c(0, 0)) geotransform_to_world(x)
px |
pixel resolution (XY, Y-negative) |
ul |
grid offset, top-left corner |
sh |
affine shear (XY) |
x |
geotransform parameters, as per |
Note that xmin/xmax are centre_of_cell (of top-left cell) unlike the geotransform which is top-left corner_of_cell. The parameters are otherwise the same, but in a different order.
vector of parameters xres, yskew, xskew, yres, xmin, ymax
world vector, as per geo_world0()
geo_world0(px = c(1, -1), ul = c(0, 0)) (gt <- geo_transform0(px = c(1, -1), ul = c(0, 0))) wf <- geotransform_to_world(gt) world_to_geotransform(wf)geo_world0(px = c(1, -1), ul = c(0, 0)) (gt <- geo_transform0(px = c(1, -1), ul = c(0, 0))) wf <- geotransform_to_world(gt) world_to_geotransform(wf)
Basic grid tools, cell, resolution, dimension, extent.
n_cell(dimension) x_res(dimension, extent = NULL) y_res(dimension, extent = NULL) n_row(dimension) n_col(dimension) xlim(dimension, extent = NULL) ylim(dimension, extent = NULL) x_min(dimension, extent = NULL) x_max(dimension, extent = NULL) y_min(dimension, extent = NULL) y_max(dimension, extent = NULL)n_cell(dimension) x_res(dimension, extent = NULL) y_res(dimension, extent = NULL) n_row(dimension) n_col(dimension) xlim(dimension, extent = NULL) ylim(dimension, extent = NULL) x_min(dimension, extent = NULL) x_max(dimension, extent = NULL) y_min(dimension, extent = NULL) y_max(dimension, extent = NULL)
dimension |
integer ncol, nrow |
extent |
numeric extent xmin,xmax,ymin,ymax |
number of cells
x resolution (width of cell)
y resolution (height of cell)
number of rows
number of cols
x extent (corner to corner)
y extent (corner to corner)
x minimum (left edge)
x maximum (right edge)
y minimum (bottom edge)
ymaximum (top edge)
n_cell(c(10, 5)) x_res(c(10, 5), c(0, 10, 0, 5)) y_res(c(10, 5), c(0, 10, 0, 5)) n_row(c(10, 5)) n_col(c(10, 5)) xlim(c(10, 5), c(0, 10, 0, 5)) ylim(c(10, 5), c(0, 10, 0, 5)) x_min(c(10, 5), c(0, 10, 0, 5)) x_max(c(10, 5), c(0, 10, 0, 5)) y_min(c(10, 5), c(0, 10, 0, 5)) y_max(c(10, 5), c(0, 10, 0, 5))n_cell(c(10, 5)) x_res(c(10, 5), c(0, 10, 0, 5)) y_res(c(10, 5), c(0, 10, 0, 5)) n_row(c(10, 5)) n_col(c(10, 5)) xlim(c(10, 5), c(0, 10, 0, 5)) ylim(c(10, 5), c(0, 10, 0, 5)) x_min(c(10, 5), c(0, 10, 0, 5)) x_max(c(10, 5), c(0, 10, 0, 5)) y_min(c(10, 5), c(0, 10, 0, 5)) y_max(c(10, 5), c(0, 10, 0, 5))
Create the extent (xlim, ylim) from the geotransform and dimensions of the grid.
gt_dim_to_extent(x, dim)gt_dim_to_extent(x, dim)
x |
geotransform parameters, as per |
dim |
dimensions x,y of grid (ncol,nrow) |
The extent is c(xmin, xmax, ymin, ymax).
4-element extent c(xmin,xmax,ymin,ymax)
gt_dim_to_extent(geo_transform0(c(1, -1), c(0, 10)), c(5, 10))gt_dim_to_extent(geo_transform0(c(1, -1), c(0, 10)), c(5, 10))
Return the overlapping extent.
intersect_extent(x, dimension, extent = NULL)intersect_extent(x, dimension, extent = NULL)
x |
extent to intersect |
dimension |
integer ncol, nrow |
extent |
numeric extent xmin,xmax,ymin,ymax |
extent
intersect_extent(c(0.5, 2.3, 1.2, 5), c(10, 5), c(0, 10, 0, 5))intersect_extent(c(0.5, 2.3, 1.2, 5), c(10, 5), c(0, 10, 0, 5))
Origin of grid alignment
origin(dimension, extent = NULL)origin(dimension, extent = NULL)
dimension |
integer ncol, nrow |
extent |
numeric extent xmin,xmax,ymin,ymax |
coordinate of grid origin
origin(c(10, 5), c(0, 10, 0, 5))origin(c(10, 5), c(0, 10, 0, 5))
Plot an extent
plot_extent(x, ..., asp = 1, add = FALSE, border = "black")plot_extent(x, ..., asp = 1, add = FALSE, border = "black")
x |
extent xmin,xmax,ymin,ymax |
... |
arguments passed to |
asp |
aspect ratio (1 by default) |
add |
add to plot or initiated one, |
border |
colour of lines of extent |
nothing, used for plot side effect
plot_extent(c(-180, 180, -90, 90)) plot_extent(c(100, 150, -60, -30), add = TRUE, border = "firebrick")plot_extent(c(-180, 180, -90, 90)) plot_extent(c(100, 150, -60, -30), add = TRUE, border = "firebrick")
raster_sfio().The sf RasterIO is the RasterIO window in a list format used by the sf package, it contains the same
information, and is created by raster_sfio().
rasterio_idx(dimension, extent) raster_sfio(dimension, fact = 1, resample = "Nearest")rasterio_idx(dimension, extent) raster_sfio(dimension, fact = 1, resample = "Nearest")
dimension |
ncols, nrows |
extent |
this is ignored |
fact |
a resizing factor |
resample |
resample algorithm for GDAL RasterIO |
RasterIO window vector 'c(x0, y0, nx0, ny0, nx, y)' see Details
rasterio_idx(dim(volcano))rasterio_idx(dim(volcano))
We create the list as used by the stars/sf GDAL IO function 'gdal_read(, RasterIO_parameters)'.
rasterio_to_sfio(x)rasterio_to_sfio(x)
x |
rasterio params as from |
Note that the input is a 4 or 6 element vector, with offset 0-based and output dimensions optional (will use the source window). The resample argument uses the syntax identical to that used in GDAL itself.
list in sf RasterIO format
rio <- rasterio0(c(0L, 0L), src_dim = c(24L, 10L)) rasterio_to_sfio(rio)rio <- rasterio0(c(0L, 0L), src_dim = c(24L, 10L)) rasterio_to_sfio(rio)
Basic function to create the window paramers as used by GDAL RasterIO.
rasterio0( src_offset, src_dim, out_dim = src_dim, resample = "NearestNeighbour" )rasterio0( src_offset, src_dim, out_dim = src_dim, resample = "NearestNeighbour" )
src_offset |
index offset (0-based, top left) |
src_dim |
source dimension (XY) |
out_dim |
output dimension (XY, optional src_dim will be used if not set) |
resample |
resampling algorith for GDAL see details |
Resampling algorithm is one of 'NearestNeighbour' (default), 'Average', 'Bilinear', 'Cubic', 'CubicSpline', 'Gauss', 'Lanczos', 'Mode', but more may be available given the version of GDAL in use.
numeric vector of values specifying offset, source dimension, output dimension
rasterio0(c(0L, 0L), src_dim = c(24L, 10L))rasterio0(c(0L, 0L), src_dim = c(24L, 10L))
Basic function to create the window parameters as used by GDAL RasterIO, in format used by sf, in 'gdal_read(,RasterIO_parameters)'.
sfio_to_rasterio(x)sfio_to_rasterio(x)
x |
a RasterIO parameter list |
a sf-RasterIO parameter list
sfio_to_rasterio(rasterio_to_sfio(rasterio0(c(0L, 0L), src_dim = c(24L, 10L))))sfio_to_rasterio(rasterio_to_sfio(rasterio0(c(0L, 0L), src_dim = c(24L, 10L))))
Whole grain buffers.
snap_extent(x, res) buffer_extent(x, res)snap_extent(x, res) buffer_extent(x, res)
x |
extent (xmin, xmax, ymin, ymax) |
res |
resolution (a grain to align to) |
extent, snapped to the resolution
snap_extent(sort(rnorm(4)), 0.01)snap_extent(sort(rnorm(4)), 0.01)
Format properties for the GDAL options.
te(extent) ts(dimension) ts_te(dimension, extent)te(extent) ts(dimension) ts_te(dimension, extent)
extent |
xmin,xmax,ymin,ymax |
dimension |
ncol, nrow |
string formatted for GDAL command line (-te -ts)
ts_te(c(10, 100), 1:4) ts(c(10, 100)) te(1:4)ts_te(c(10, 100), 1:4) ts(c(10, 100)) te(1:4)
currently only return centre coords
vaster_boundary(dimension, extent = NULL)vaster_boundary(dimension, extent = NULL)
dimension |
integer ncol, nrow |
extent |
numeric extent xmin,xmax,ymin,ymax |
vaster_boundary(c(3, 4))vaster_boundary(c(3, 4))
Generate list of x and y rectilinear coordinates with z matrix.
vaster_listxyz(dimension, extent = NULL, data = NULL)vaster_listxyz(dimension, extent = NULL, data = NULL)
dimension |
integer ncol, nrow |
extent |
numeric extent xmin,xmax,ymin,ymax |
data |
data values (length of the product of 'dimension') |
The rectilinear coordinates are degenerate (just a product of extent/dimension).
list with elementx x,y,z as per graphics::image
vaster_listxyz(c(10, 5), c(0, 10, 0, 5)) ## see https://gist.github.com/mdsumner/b844766f28910a3f87dc2c8a398a3a13vaster_listxyz(c(10, 5), c(0, 10, 0, 5)) ## see https://gist.github.com/mdsumner/b844766f28910a3f87dc2c8a398a3a13
Matrix of xyz values in raster order.
vaster_long(dimension, extent = NULL, data = NULL, raster_order = TRUE)vaster_long(dimension, extent = NULL, data = NULL, raster_order = TRUE)
dimension |
integer ncol, nrow |
extent |
numeric extent xmin,xmax,ymin,ymax |
data |
data values |
raster_order |
use raster order or native R matrix order |
Use 'raster_order = FALSE' for traditional R matrix x,y order
matrix of coordinates x,y
vaster_long(c(10, 5), c(0, 10, 0, 5)) # see https://gist.github.com/mdsumner/b844766f28910a3f87dc2c8a398a3a13vaster_long(c(10, 5), c(0, 10, 0, 5)) # see https://gist.github.com/mdsumner/b844766f28910a3f87dc2c8a398a3a13
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")vcrop(x, dimension, extent = NULL, ..., snap = "out")
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" |
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.
## any arbitrary extent x <- c(sort(runif(2, -180, 180)), sort(runif(2, -90, 90))) print(x) vcrop(x, c(360, 180), c(-180, 180, -90, 90))## any arbitrary extent x <- c(sort(runif(2, -180, 180)), sort(runif(2, -90, 90))) print(x) vcrop(x, c(360, 180), c(-180, 180, -90, 90))
Convert world vector (centre offset) and x,y spacing to geotransform format.
world_to_geotransform(x)world_to_geotransform(x)
x |
worldfile parameters, as per |
geotransform vector, see geo_transform0()
(wf <- geo_world0(px = c(1, -1), ul = c(0, 0))) gt <- world_to_geotransform(wf) geotransform_to_world(gt)(wf <- geo_world0(px = c(1, -1), ul = c(0, 0))) gt <- world_to_geotransform(wf) geotransform_to_world(gt)