rsaga.inverse.distance {RSAGA} | R Documentation |
Spatial interpolation of point data using inverse distance to a power (inverse distance weighting, IDW), nearest neighbors, or modified quadratic shephard.
rsaga.inverse.distance(in.shapefile, out.grid, field, power = 1, maxdist = 100, nmax = 10, target = rsaga.target(), ...) rsaga.nearest.neighbour(in.shapefile, out.grid, field, target = rsaga.target(), ...) rsaga.modified.quadratic.shephard(in.shapefile, out.grid, field, quadratic.neighbors = 13, weighting.neighbors = 19, target = rsaga.target(), ...)
in.shapefile |
Input: point shapefile
(default extension: .shp ). |
out.grid |
Output: filename for interpolated grid (SAGA grid file). Existing files will be overwritten! |
field |
numeric(!): number (not name!) of attribute in the shapefile's attribute table to be interpolated; the first attribute is represented by a zero. |
power |
numeric (>0): exponent used in inverse distance weighting (usually 1 or 2) |
maxdist |
numeric: maximum distance of points to be used for inverse distance interpolation (search radius) |
nmax |
Maximum number of nearest points to be used for interpolation |
quadratic.neighbors |
integer >=5; ?? |
weighting.neighbors |
integer >=3; ?? |
target |
list: parameters identifying the target area,
e.g. the lower left corner and size of grid, or name of a
reference grid; see rsaga.target . |
... |
Optional arguments to be passed to rsaga.geoprocessor ,
including the env RSAGA geoprocessing environment. |
Inverse distance weighting (IDW) uses module 0 in the
SAGA library grid_gridding
.
Nearest neighbour interpolation uses module 1, and triangulation
is performed by module 4.
See the example section in the help file for write.shapefile
in package shapefiles
to learn how to apply these interpolation
functions to a shapefile exported from a data.frame.
Modified Quadratic Shephard method: based on module 660 in TOMS (see references).
Alexander Brenning (R interface), Andre Ringeler and Olaf Conrad (SAGA modules)
QSHEP2D: Fortran routines implementing the Quadratic Shepard method for bivariate interpolation of scattered data (see R. J. Renka, ACM TOMS 14 (1988) pp.149-150). Classes: E2b. Interpolation of scattered, non-gridded multivariate data.
rsaga.ordinary.kriging
, and idw
in package
gstat
.