raster: cellFrom – R documentation

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cellFrom

Get cell, row, or column number

Description

Get cell number(s) of a Raster* object from row and/or column numbers. Cell numbers start at 1 in the upper left corner, and increase from left to right, and then from top to bottom. The last cell number equals the number of cells of the Raster* object.

Usage

cellFromRowCol(object, row, col, ...)
cellFromRowColCombine(object, row, col, ...)
cellFromRow(object, rownr)
cellFromCol(object, colnr)
colFromX(object, x)
rowFromY(object, y)
cellFromXY(object, xy)
cellFromLine(object, lns)
cellFromPolygon(object, p, weights=FALSE)
fourCellsFromXY(object, xy, duplicates=TRUE)

Arguments

`object`	Raster* object (or a SpatialPixels* or SpatialGrid* object)
`colnr`	column number; or vector of column numbers
`rownr`	row number; or vector of row numbers
`col`	column number; or vector of column numbers
`row`	row number; or vector of row numbers
`x`	x coordinate(s)
`y`	y coordinate(s)
`xy`	matrix of x and y coordinates, or a SpatialPoints or SpatialPointsDataFrame object
`lns`	SpatialLines object
`p`	SpatialPolygons object
`weights`	Logical. If `TRUE`, the fraction of each cell that is covered is also returned
`duplicates`	Logical. If `TRUE`, the same cell number can be returned twice (if the point in the middle of a division between two cells) or four times (if a point is in the center of a cell)
`...`	additional arguments (none implemented)

Details

cellFromRowCol returns the cell numbers obtained for each row / col number pair. In contrast, cellFromRowColCombine returns the cell numbers obtained by the combination of all row and column numbers supplied as arguments.

fourCellsFromXY returns the four cells that are nearest to a point (if the point falls on the raster). Also see adjacent.

Value

vector of row, column or cell numbers. cellFromLine and cellFromPolygon return a list, fourCellsFromXY returns a matrix.

Examples

r <- raster(ncols=10, nrows=10)
cellFromRowCol(r, 5, 5)
cellFromRowCol(r, 1:2, 1:2)
cellFromRowColCombine(r, 1:3, 1:2)
cellFromCol(r, 1)
cellFromRow(r, 1)

colFromX(r, 0.5)
rowFromY(r, 0.5)
cellFromXY(r, cbind(c(0.5,5), c(15, 88)))
fourCellsFromXY(r, cbind(c(0.5,5), c(15, 88)))

cds1 <- rbind(c(-180,-20), c(-160,5), c(-60, 0), c(-160,-60), c(-180,-20))
cds2 <- rbind(c(80,0), c(100,60), c(120,0), c(120,-55), c(80,0))
pols <- SpatialPolygons(list(Polygons(list(Polygon(cds1)), 1), Polygons(list(Polygon(cds2)), 2)))
cellFromPolygon(r, pols)

raster

Geographic Data Analysis and Modeling

v3.4-10

GPL (>= 3)

Authors

Robert J. Hijmans [cre, aut] (<https://orcid.org/0000-0001-5872-2872>), Jacob van Etten [ctb], Michael Sumner [ctb], Joe Cheng [ctb], Dan Baston [ctb], Andrew Bevan [ctb], Roger Bivand [ctb], Lorenzo Busetto [ctb], Mort Canty [ctb], Ben Fasoli [ctb], David Forrest [ctb], Aniruddha Ghosh [ctb], Duncan Golicher [ctb], Josh Gray [ctb], Jonathan A. Greenberg [ctb], Paul Hiemstra [ctb], Kassel Hingee [ctb], Institute for Mathematics Applied Geosciences [cph], Charles Karney [ctb], Matteo Mattiuzzi [ctb], Steven Mosher [ctb], Babak Naimi [ctb], Jakub Nowosad [ctb], Edzer Pebesma [ctb], Oscar Perpinan Lamigueiro [ctb], Etienne B. Racine [ctb], Barry Rowlingson [ctb], Ashton Shortridge [ctb], Bill Venables [ctb], Rafael Wueest [ctb]

Initial release

2021-05-02