sperich (version 1.5-9)

edgeNotValid: Edge-Water-Test

Description

This function checks if an edge would cross a water or mountain surface.

Usage

edgeNotValid(grid,point.a, point.b, landwatermask, upperbound)

Value

A boolean value which determines if the edge would cross a water or mountain surface.

Arguments

grid

A grid to which the edge should be added if it hits no water or mountain surfaces.

point.a

A point in a grid given by its row and column.

point.b

A point in a grid given by its row and column.

landwatermask

A grid containing the land-water-information of the observed area. If a grid cell containes no land, the value of the cell in the landwatermask is -1, otherwise it is 0. Additional, height-informations could be added for land surfaces. In this case, take care of the 'upperbound' value.

upperbound

This value determines the height (based on values in 'landwatermask') which is considered to be a barrier for species distribution.

Author

Maximilian Lange, Sven Lautenbach

Details

This function checks if an edge would cross a water or mountain surface.

Examples

##load data
data(dataset.all.species)
data(dataset.landwater)

##initialize variables
distance <- 5

##create grid parameters
dimension <- getDimension(dataset.all.species)
origin <- getOrigin(dataset.all.species)

##create landwatermask
landwatermask.nocoast <- createLandwatermask(dataset.landwater, dimension, origin)

##extract datasets of one species out of database
dataset.one.species <- extract.species(dataset.all.species, 3)

##create grid
grid <- matrix(0,dimension[1],dimension[2])

##add points
grid <- data.into.Grid(dataset.one.species, dimension, origin)

##points to list
points <- which(grid > 0)
points.xy <- list()
for (i in 1:length(points)){
	points.xy[[i]] <- c(ifelse((points[i] %% dimension[1]) == 0, dimension[1], 
			points[i] %% dimension[1]), ceiling(points[i]/dimension[1]))
}

##Edge-Water-Test
check <- edgeNotValid(grid, points.xy[[1]],points.xy[[2]], 
			landwatermask.nocoast, 1000)
print(check)