Create a pgeometry object with components

create_pgeometry() creates a pgeometry object from a data.frame or tibble object, a list of components, or a list of spatial plateau objects.

Usage

create_pgeometry(x, type, is_valid = TRUE)

Arguments

x

A list of component objects, a list of pgeometry objects or a data.frame/tibble object. For PLATEAUPOINT, PLATEAULINE and PLATEAUREGION, the type of each component must be the same for all components.

type

A character value that indicates the type of the desired pgeometry object. It should be either "PLATEAUPOINT", "PLATEAULINE", "PLATEAUREGION", "PLATEAUCOMPOSITION", or "PLATEAUCOLLECTION". It must be compatible with the components given in x parameter.

is_valid

A Boolean value to check whether the user wants to validate the created spatial plateau object at the end. If is_valid = TRUE, it calls validObject() method.

Value

A pgeometry object.

Details

create_pgeometry() is a flexible function that creates a pgeometry object by using the values given in x. This object is built by using either a list of component objects, a list of pgeometry objects or a data.frame (or tibble) object. If a data.frame or tibble object is given as input, its columns must have the following format: (i) first column is an sfc object, and (ii) the second columns consists of the membership degree of each respective object of the sfc column.

By default, this function checks if the resulting spatial plateau object is valid. That is, it checks whether all constraints defined by the Spatial Plateau Algebra are satisfied. For instance, the components of a plateau point, plateau line, or plateau region must be adjacent or disjoint from each other and have to be unique membership degrees.

If you are sure that the component objects provided to this function satisfy all the constraints, then you can use is_valid = FALSE to improve the performance of this function.

References

Carniel, A. C.; Venâncio, P. V. A. B; Schneider, M. fsr: An R package for fuzzy spatial data handling. Transactions in GIS, vol. 27, no. 3, pp. 900-927, 2023.

Underlying concepts and formal definitions of spatial plateau data types are explained in detail in:

• 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.

• Carniel, A. C.; Schneider, M. Spatial Data Types for Heterogeneously Structured Fuzzy Spatial Collections and Compositions. In Proceedings of the 2020 IEEE International Conference on Fuzzy Systems (FUZZ-IEEE 2020), pp. 1-8, 2020.

Examples

library(sf)

# Creating some components
pts <- rbind(c(0, 2), c(4, 2))
# Point components
pcp1 <- create_component(st_multipoint(pts), 0.3)
pcp2 <- create_component("MULTIPOINT((2 2), (2 4), (2 0))", 0.5)
pcp3 <- create_component("MULTIPOINT((1 1), (3 1), (1 3), (3 3))", 0.9)
# Line components
lcp1 <- create_component("LINESTRING(0 0, 1 1.5)", 0.2)
lcp2 <- create_component("LINESTRING(1 3, 1 2, 2 0.5)", 0.5)
lcp3 <- create_component("LINESTRING(2 1.2, 3 1.6, 4 4)", 0.7)
lcp4 <- create_component("LINESTRING(1 1.5, 2 1.2)", 1.0)
# Polygon components
rcp1 <- create_component("POLYGON((0 0, 1 4, 2 2, 0 0))", 0.4)
rcp2 <- create_component("POLYGON((2 0.5, 4 1, 4 0, 2 0.5))", 0.8)

# Creating spatial plateau objects from lists of components
pp <- create_pgeometry(list(pcp1, pcp2, pcp3), "PLATEAUPOINT")
pl <- create_pgeometry(list(lcp1, lcp3, lcp4), "PLATEAULINE")
pr <- create_pgeometry(list(rcp1, rcp2), "PLATEAUREGION")
pcm <- create_pgeometry(list(pcp1, pcp2, lcp1, lcp2, lcp3, rcp2), "PLATEAUCOMPOSITION")

# Creating a spatial plateau objects from a list of spatial plateau objects
pcl <- create_pgeometry(list(pp, pr, pcm), "PLATEAUCOLLECTION")

# Converting pp into a tibble
pp
#> [1] "PLATEAUPOINT ((MULTIPOINT ((0 2), (4 2)), 0.3), (MULTIPOINT ((2 2), (2 4), (2 0)), 0.5), (MULTIPOINT ((1 1), (3 1), (1 3), (3 3)), 0.9))"
tibble_pp <- as_tibble(pp)
tibble_pp
#> # A tibble: 3 × 2
#>                       geometry    md
#>                   <MULTIPOINT> <dbl>
#> 1               ((0 2), (4 2))   0.3
#> 2        ((2 2), (2 4), (2 0))   0.5
#> 3 ((1 1), (3 1), (1 3), (3 3))   0.9

# Creating a spatial plateau point from the previous tibble
equivalent_pp <- create_pgeometry(tibble_pp, "PLATEAUPOINT")
equivalent_pp
#> [1] "PLATEAUPOINT ((MULTIPOINT ((0 2), (4 2)), 0.3), (MULTIPOINT ((2 2), (2 4), (2 0)), 0.5), (MULTIPOINT ((1 1), (3 1), (1 3), (3 3)), 0.9))"