SpatialPixelsTopography: Creates a 'SpatialPixelsTopography'

In miquelcaceres/meteoland: Landscape Meteorology Tools

Description

Function SpatialPixelsTopography creates an object of class SpatialPixelsTopography-class containing topographic variables for a set of points.

Usage

SpatialPixelsTopography(points, elevation, slope, aspect,
                        tolerance = sqrt(.Machine$double.eps), 
                        proj4string = CRS(as.character(NA)), round = NULL, 
                        grid = NULL)

Arguments

points	An object of class SpatialPoints-class or a numeric matrix of coordinates.
elevation	Elevation values (in m) of the points.
slope	Slope values (in degrees) of the points.
aspect	Aspect values (in degrees from North) of the points.
tolerance	Precision up to which extent points should be exactly on a grid.
proj4string	Object of class CRS in the first form only used when points does not inherit from Spatial.
round	default NULL, otherwise a value passed to as the digits argument to round for setting cell size.
grid	Grid topology using an object of class GridTopology; a value of NULL implies that this will be derived from the point coordinates.

Value

Function SpatialPixelsTopography returns an object 'SpatialPixelsTopography-class'.

Author(s)

Miquel De Cáceres Ainsa, Biodiversity and Landscape Ecology Laboratory, Centre Tecnologic Forestal de Catalunya

See Also

SpatialPixelsTopography-class

Examples

data(examplegridtopography)

#Creates spatial topography pixels as a subset of points in the grid
spt = as(examplegridtopography,"SpatialPointsTopography")
cc = spt@coords
center = 5160
d = sqrt((cc[,1]-cc[center,1])^2+(cc[,2]-cc[center,2])^2)
p = which(d<3000) #Select points at maximum distance of 3km from center
spxt = SpatialPixelsTopography(spt[p], spt$elevation[p],
                              spt$slope[p],
                              spt$aspect[p])

#Alternatively, use coercing and subsetting (drop = TRUE causes grid to be recalculated) 
spxt = as(examplegridtopography, "SpatialPixelsTopography")[p, drop=TRUE]          
                              
#Display data
spplot(spxt, variable="elevation", scales=list(draw=TRUE))
spplot(spxt, variable="slope", scales=list(draw=TRUE))
spplot(spxt, variable="aspect", scales=list(draw=TRUE))

miquelcaceres/meteoland documentation built on May 8, 2019, 11:57 p.m.