rasterListFun {rasterList}

Execution of the elements of a RasterList

Description

This fuction transmors a generic RasterList-class object into another RasterList-class object where elemets are all function-type.

Usage

rasterListFun(object)

Arguments

object

an object to be coerced to RasterList-class

Value

This function works with RasterList-class objects in which all elements of object@list slot are functions. It returns a "global" function that works at "raster" scale. The returned function will have the following usage signature: fun(xval,...) where one xval (if its lengths is different from 1) element is the applied to each element and ... are further common arguments.

Examples

library(sp)
library(rasterList)
library(soilwater)
set.seed(1234)
data(meuse.grid)
data(meuse)
coordinates(meuse.grid) <- ~x+y
coordinates(meuse) <- ~x+y
gridded(meuse.grid) <- TRUE


soilmap <- stack(meuse.grid)[['soil']]
elevmap <- rasterize(x=meuse,y=soilmap,field="elev",fun=mean)
soilparcsv <- system.file("external/soil_data.csv",package="soilwater")
soilpar <- read.table(soilparcsv,stringsAsFactors=FALSE,header=TRUE,sep=",")
## From help(meuse,help_type="html")
##soil type according to the 1:50 000 soil map of the Netherlands. 
## 1 = Rd10A (Calcareous weakly-developed meadow soils, light sandy clay); 
## 2 = Rd90C/VII (Non-calcareous weakly-developed meadow soils, heavy sandy clay to light clay); 
## 3 = Bkd26/VII (Red Brick soil, fine-sandy, silty light clay)
soiltype_id <- c(1,2,3)
soiltype_name <- c("sandy clay","sandy clay","silty clay loam")

meuse.soilrasterlist <- rasterList(soilmap,FUN=function(i,soiltype_name,soilpar){
			
		o <- NULL
		if (!is.na(i)) {
			ii <- which(soilpar$type==soiltype_name[i])	
		    o <- soilpar[ii,]				
			type <- o[["type"]]
			o <- o[names(o)!="type"]
			o <- o[names(o)!="Ks_m_per_hour"]
			names(o)[names(o)=="Ks_m_per_sec"] <- "ks"
			names(o)[names(o)=="swc"] <- "theta_sat"
			names(o)[names(o)=="rwc"] <- "theta_res"
			attr(o,"type") <- type
			## add noise
			noise <- rnorm(length(o))
			o <- o*(1+0.005*noise)
				
			o["m"] <- 1-1/o["n"]
				
				
		} else {
				
			o <- soilpar[which(soilpar$type==soiltype_name[1]),]
			type <- o[["type"]]
			o <- o[names(o)!="type"]
			o <- o[names(o)!="Ks_m_per_hour"]
			names(o)[names(o)=="Ks_m_per_sec"] <- "ks"
			names(o)[names(o)=="swc"] <- "theta_sat"
			names(o)[names(o)=="rwc"] <- "theta_res"
			o[] <- NA
		}
			
		return(o)
},soiltype_name=soiltype_name,soilpar=soilpar)


meuse.swclist <- rasterList(meuse.soilrasterlist,FUN=function(x) {
			
			o <- NA
##			swc       rwc   alpha       n         m           ks
##			9 0.4295507 0.1093227 3.39387 1.39617 0.2837546 2.018317e-07
		
			
			o <- function(psi,...,func="swc"){
				
				args <- c(list(psi=psi,...),as.list(x))
				oo <- do.call(args=args,what=get(func))
				return(oo)
				
			}
			
			
			
			
			
			
			
			return(o)
			
		})


### RasterList with soil water retenction curves (One for each cell!) 

swcfunr <- rasterListFun(meuse.swclist)

## RasterLayer of soil water content assuming a uniformly distrrubted pressure head 
psi <- -0.9
soil_water_content <- raster(swcfunr(psi))
plot(soil_water_content)

## RasterLayer of soil water content from  a generic map of soil water pressure head
psi <- 0.2-(elevmap-(5))
psi[] <- -0.9+0.1*rnorm(ncell(psi[])) ## Alternatively to the values of the previous line!
soil_water_content <- raster(swcfunr(psi))
plot(soil_water_content)

## END