Spread: Spreading measure of several spatial samples
In SpotSampling: SPatial and Optimally Temporal (SPOT) Sampling

Description Usage Arguments Value Author(s) References See Also Examples

View source: R/Spread.R

Measure the spread of several spatial samples depending on inclusion probabilities and spatial coordinates. Two spreading criteria are available: one based on the space partition of Voronoi polygons and one based on Moran's I index (see references).

1	Spread(S, pik, coord, criteria)

`S`	a matrix that contains samples in columns. Matrix rows correspond to the units. It could be matrix of temporal samples returned by function `Spot`.
`pik`	a matrix of temporal inclusion probabilities. Columns of `pik` correspond to samples, and rows correspond to the units.
`coord`	a matrix that contains spatial coordinates in columns. Matrix rows correspond to the units.
`criteria`	it specifies the criteria used to measure samples spreading. `criteria = "IB"`: the criteria based on Moran's I index is used (see `IB`), `criteria = "sb"`: the criteria based on Moran's I index is used (see `sb`).

a vector that contains values of the spreading measure of the samples in columns of S.

Esther Eustache esther.eustache@unine.ch

Grafstrom, A., Lundstrom, N. L. P., and Schelin, L. (2012). Spatially balanced sampling through the pivotal method. Biometrics, 68(2):514-520.

Jauslin, R. and Tille, Y. (2019). Spatial spread sampling using weakly associated vectors. Statistical Office, University of Neuchatel.

IB, sb.

set.seed(1)
## Coordinates in two dimensions of 10 units ##
coord <- matrix(stats::runif(10*2), ncol=2)
## Temporal inclusion probabilities with 3 waves and 4 units ##
pik <- matrix(rep(0.2,10*3), ncol = 3, byrow = TRUE)
## Spot method to obtain temporal samples ##
S <- Spot(pik, coord)
## Compute IB criteria ##
Spread(S, pik, coord, criteria = 'IB')