transfR (version 1.1.4)

hdist: Geographical distance between catchments

Description

Calculate distances between two sets of catchments using their spatial support.

Usage

hdist(x, y, ...)
# S3 method for sfc
hdist(
  x,
  y,
  method = "rghosh",
  gres = 5,
  ditself = FALSE,
  maxsample = 25000,
  proj = NULL,
  parallel = FALSE,
  cores = NULL,
  verbose = TRUE,
  ...
)
# S3 method for sf
hdist(x, y, ...)
# S3 method for stars
hdist(x, y, ...)
# S3 method for transfR
hdist(x, y, method = "rghosh", weightO = 0.8, weightC = 0.2, ...)

Value

A matrix of class units with the catchments of x organised in rows and the catchments of y organised in columns.

Arguments

x

sf, stars or transfR object of the first catchments

y

sf, stars or transfR object of the second catchments

...

further arguments passed to or from other methods

method

the method to use for computing distance. This must be one of "ghosh", "rghosh", "points", "centroids", "combined"

gres

resolution of spatial discretisation (number of points by km²) for Ghosh distance

ditself

logical value indicating if the distance to itself should be computed. It will add one row and one column in the distance matrix. Only used if method is "ghosh"

maxsample

maximum size of sampling points for each catchments during spatial discretisation

proj

logical indicating if spatial layer are using a projection. If TRUE, euclidean distance is used. If FALSE, the great-circle distance is used

parallel

logical indicating whether the computation should be parallelised. Could be a vector of length two to distinguish between parallelisation of sampling and Ghosh distance (because sampling over large areas can be memory intensive)

cores

the number of cores to use for parallel execution if parallel is TRUE. If not specified, the number of cores is set to the value of parallel::detectCores(). Similarly to parallel, it could be a vector of length two to distinguish between parallelisation of sampling and Ghosh distance

verbose

boolean indicating if information messages should be written to the console

weightO

weight given to the distance between outlets if method is "combined"

weightC

weight given to the distance between centroids if method is "combined"

Details

The method "ghosh" refers to a simplification of the distance defined by Ghosh1951;textualtransfR as proposed by Gottschalk1993,Gottschalk2011;textualtransfR. The rescaled Ghosh distance (method "rghosh") is calculated following deLavenne2016;textualtransfR.

References

Ghosh1951transfR

Gottschalk1993transfR

Gottschalk2011transfR

deLavenne2016transfR

Examples

data(Oudon)
catchments <- st_geometry(Oudon$obs)
hdist(x = catchments[1:2], y = catchments[3:5], gres = 5, method = "rghosh",
parallel=c(FALSE, TRUE), cores=2)