# variogram: Empirical Variogram from Spatial Data In babaknaimi/elsa: Entropy-Based Local Indicator of Spatial Association

 Variogram R Documentation

## Empirical Variogram from Spatial Data

### Description

Compute sample (empirical) variogram from spatial data. The function returns a binned variogram and a variogram cloud.

### Usage

``````Variogram(x, width, cutoff,...)
``````

### Arguments

 `x` a spatial object (`RasterLayer` or `SpatialPointsDataFrame` or `SpatialPolygonsDataFrame`) `width` the lag size (width of subsequent distance intervals) into which cell pairs are grouped for semivariance estimates. If missing, the cell size (raster resolution) is assigned. `cutoff` spatial separation distance up to which cell pairs are included in semivariance estimates; as a default, the length of the diagonal of the box spanning the data is divided by three. `...` Additional arguments including `cloud` that specifies whether a variogram cloud should be included to the output (default is `FALSE`), `zcol` (when `x` is Spatial* object, specifies the name of the variable in the dataset; `longlat` (when `x` is Spatial* object, spacifies whether the dataset has a geographic coordinate system; `s` (only when x is a Raster object, it would be useful when the dataset is big, so then by specifying `s`, the calculation would be based on a sample with size `s` drawn from the dataset, default is `NULL` means all cells should be contributed in the calculations)

### Details

Variogram is a graph to explore spatial structure in a single variable. A variogram summarizes the spatial relations in the data, and can be used to understand within what range (distance) the data is spatially autocorrelated.

### Value

 `Variogram` an object containing variogram cloud and the variogram within each distance interval

### Author(s)

Babak Naimi naimi.b@gmail.com

### References

Naimi, B., Hamm, N. A., Groen, T. A., Skidmore, A. K., Toxopeus, A. G., & Alibakhshi, S. (2019). ELSA: Entropy-based local indicator of spatial association. Spatial statistics, 29, 66-88.

### Examples

``````
file <- system.file('external/dem_example.grd',package='elsa')
r <- raster(file)
plot(r,main='a continuous raster map')

en <- Variogram(r, width=2000)

plot(en)

``````

babaknaimi/elsa documentation built on Jan. 28, 2024, 10 a.m.