fsr (version 1.0.2)

fsr_numerical_operations: Fuzzy numerical operations

Description

Fuzzy numerical operations are given as a family of functions that implements spatial plateau metric operations. These functions extract metric properties from spatial plateau objects, such as the area of a plateau region object and the length of a plateau line object.

Usage

spa_avg_degree(pgo)
spa_ncomp(pgo)
spa_area(pr)
spa_perimeter(pr)
spa_length(pl)

Value

A numerical value.

Arguments

pgo

A pgeometry object of any type.

pr

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

pl

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

Details

These functions calculate numerical properties from spatial plateau objects (i.e., pgeometry objects). Some of them are type-independent. This means that the parameter can be a pgeometry object of any type. The type-independent functions are:

• spa_avg_degree calculates the average membership degree of a spatial plateau object.

• spa_ncomp returns the number of components of a spatial plateau object.

The remaining functions are type-dependent. This means that the parameter have to be of a specific type. The type-dependent functions are:

• spa_area computes the area of a plateau region object. Thus, its parameter has to be a PLATEAUREGION object.

• spa_perimeter computes the perimeter of a plateau region object. Thus, its parameter has to be a PLATEAUREGION object.

• spa_length computes the length of a plateau line object. Thus, its parameter has to be a PLATEAULINE object.

References

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

library(sf)
library(tibble)

pts1 <- rbind(c(1, 2), c(3, 2))
comp1 <- component_from_sfg(st_multipoint(pts1), 0.2) 
comp2 <- component_from_sfg(st_point(c(1, 5)), 0.8)  

pp <- create_pgeometry(list(comp1, comp2), "PLATEAUPOINT")

# calculating the average degree and number of components of pp

spa_avg_degree(pp)
spa_ncomp(pp)

# calculating the area and perimeter

set.seed(345)

# some random points to create plateau region objects by using the function spa_creator
tbl = tibble(x = runif(10, min= 0, max = 20), 
             y = runif(10, min = 0, max = 30), 
             z = runif(10, min = 0, max = 100))

#getting the convex hull on the points to clip 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, fuzz_policy = "fcp", k = 2, base_poly = ch)

spa_area(pregions$pgeometry[[1]])
spa_area(pregions$pgeometry[[2]])

spa_perimeter(pregions$pgeometry[[1]])
spa_perimeter(pregions$pgeometry[[2]])

# calculating the length of a plateau line object

lpts1 <- rbind(c(0, 0), c(1, 1))
lpts2 <- rbind(c(1, 1), c(1.2, 1.9), c(2, 1))
lpts3 <- rbind(c(2, 1), c(1.5, 0.5))

cp1 <- component_from_sfg(st_linestring(lpts1), 0.4)
cp2 <- component_from_sfg(st_linestring(lpts2), 1)
cp3 <- component_from_sfg(st_linestring(lpts3), 0.7)

pline <- create_pgeometry(list(cp1, cp2, cp3), "PLATEAULINE")

spa_length(pline)