SDMTools (version 1.1-221)

asc.from.raster: 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)

Value

Returns an object of class requested.

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.

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)