fsr (version 1.0.0)

spa_contour: Capturing the frontier of a plateau region object

Description

This function extracts the frontier (i.e., linear boundary) of a plateau region object by maintaining its membership degrees.

Usage

spa_contour(pregion)

Arguments

pregion

A pgeometry object of the type PLATEAUREGION. It throws an error if a different type is given.

Value

A pgeometry object of the type PLATEAULINE that represents the contour (i.e. frontier) of a plateau region object given as input.

Details

It employs the definition of fuzzy frontier of a fuzzy region object in the context of spatial plateau algebra (as defined in the references). The fuzzy frontier of a fuzzy region object A collects all single points of A, preserving its membership degrees, that are not in the interior of its support.

IMPORTANT NOTE: Fuzzy frontier is different from fuzzy boundary (see spa_boundary_region).

References

• Carniel, A. C.; Schneider, M. A Conceptual Model of Fuzzy Topological Relationships for Fuzzy Regions. In Proceedings of the 2016 IEEE International Conference on Fuzzy Systems (FUZZ-IEEE 2016), pp. 2271-2278, 2016.

• Carniel, A. C.; Schneider, M. Spatial Plateau Algebra: An Executable Type System for Fuzzy Spatial Data Types. In Proceedings of the 2018 IEEE International Conference on Fuzzy Systems (FUZZ-IEEE 2018), pp. 1-8, 2018.

Examples

# NOT RUN {
library(tibble)
library(sf)
library(FuzzyR)

set.seed(123)

# some random points to create pgeometry objects by using the function spa_creator
tbl = tibble(x = runif(10, min= 0, max = 30), 
             y = runif(10, min = 0, max = 50), 
             z = runif(10, min = 0, max = 100))

classes <- c("category-1", "category-2")
mf1 <- genmf("trapmf", c(0, 5, 20, 35))
mf2 <- genmf("trimf", c(35, 80, 100))

#getting the convex hull on the points to clipping the construction of plateau region objects
pts <- st_as_sf(tbl, coords = c(1, 2))
ch <- st_convex_hull(do.call(c, st_geometry(pts)))

pregions <- spa_creator(tbl, classes = classes, mfs = c(mf1, mf2), base_poly = ch)

# capturing and showing the frontier of each pgeometry object previously created
frontier_pregion1 <- spa_contour(pregions$pgeometry[[1]]) 
frontier_pregion2 <- spa_contour(pregions$pgeometry[[2]])

plot(pregions$pgeometry[[1]])
plot(frontier_pregion1)

plot(pregions$pgeometry[[2]])
plot(frontier_pregion2)

# }