R: Update raster cells of files (on disk)

update {raster} | R Documentation

## Update raster cells of files (on disk)

### Description

Update cell values of a file (i.e., cell values on disk) associated with a RasterLayer or RasterBrick.

User beware: this function _will_ make changes to your file (first make a copy if you are not sure what you are doing).

Writing starts at a cell number `cell`. You can write a vector of values (in cell order), or a matrix. You can also provide a vector of cell numbers (of the same length as vector `v`) to update individual cells.

See `writeFormats` for supported formats.

### Usage

    ## S4 method for signature 'RasterLayer'
    update(object, v, cell, ...)
    ## S4 method for signature 'RasterBrick'
    update(object, v, cell, band, ...)

### Arguments

`object` | RasterLayer or RasterBrick that is associated with a file
`v` | vector or matrix with new values
`cell` | cell from where to start writing. Or a vector of cell numbers if v is a vector of the same length

.

`band` | band (layer) to update (for RasterBrick objects)

.

`...` | additional arguments. None implemented

### Value

RasterLayer or RasterBrick

### Examples

    ## Not run:
    # setting up an example RasterLayer with file
    r <- raster(nrow=5, ncol=10, vals=0)
    r <- writeRaster(r, rasterTmpFile(), overwrite=TRUE, datatype='INT2S')
    as.matrix(r)

    # update with a vector starting a cell
    r <- update(r, v=rep(1, 5), cell=6)
    # 99.99 gets rounded because this is an integer file
    r <- update(r, v=9.99, cell=50)
    as.matrix(r)

    # update with a vector of values and matching vector of cell numbers
    r <- update(r, v=5:1, cell=c(5,15,25,35,45))
    as.matrix(r)

    # updating with a marix, anchored at a cell number
    m <- matrix(1:10, ncol=2)
    r <- update(r, v=m, cell=2)
    as.matrix(r)

    ## End(Not run)

[Package raster version 3.3-7 Index]