R: Get cell, row, or column number

cellFrom {raster} | R Documentation

## 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.

### See Also

`xyFromCell, cellsFromExtent, rowColFromCell`

### 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)

[Package raster version 3.3-7 Index]