R: Raster conversion functions for adehabitat, raster and sp...

asc.from.raster {SDMTools} | R Documentation

## Raster conversion functions for adehabitat, raster and sp packages

### Description

`asc.from.raster` and `asc.from.sp` extracts data from objects of class 'RasterLayer' (raster package) and class 'SpatialGridDataFrame' (sp package) into an object of class 'asc' (SDMTools & adehabitat packages).
`raster.from.asc` and `sp.from.asc` does the reverse.
`as.asc` creates an object of class 'asc' (SDMTools & adehabitat packages) from a matrix of data. Code & helpfile associated with `as.asc` were modified from adehabitat package.

### Usage

    asc.from.raster(x)

    raster.from.asc(x, projs = NA)

    asc.from.sp(x)

    sp.from.asc(x, projs = CRS(as.character(NA)))

    as.asc(x, xll = 1, yll = 1, cellsize = 1, type = c("numeric", "factor"),
      lev = levels(factor(x)))

### Arguments

`x` | is an object of class 'asc', 'RasterLayer' or 'SpatialGridDataFrame'. For the function `as.asc`, a matrix
`projs` | is a CRS projection string of the Proj4 package
`xll` | the x coordinate of the center of the lower left pixel of the map
`yll` | the y coordinate of the center of the lower left pixel of the map
`cellsize` | the size of a pixel on the studied map
`type` | a character string. Either `"numeric"` or `"factor"`
`lev` | if `type = "factor"`, either a vector giving the labels of the factor levels, or the name of a file giving the correspondence table of the map (see adehabitat as.asc helpfile details)

### Details

These functions provide capabilities of using scripts / functions from many packages including adehabitat (plus e.g, SDMTools), sp (plus e.g., maptools, rgdal) and raster.

### Value

Returns an object of class requested.

### Author(s)

Jeremy VanDerWal jjvanderwal@gmail.com

### Examples

    #create a simple object of class 'asc'
    tasc = as.asc(matrix(rep(x=1:10, times=1000),nr=100)); print(tasc)
    str(tasc)

    #convert to RasterLayer
    traster = raster.from.asc(tasc)
    str(traster)

    #convert to SpatialGridDataFrame
    tgrid = sp.from.asc(tasc)
    str(tgrid)

    #create a basic object of class asc
    tasc = as.asc(matrix(rep(x=1:10, times=1000),nr=100)); print(tasc)

[Package SDMTools version 1.1-221.2 Index]