pixel_subcategory: Creates a subcategory object

Description

Creates an object of class pixel_subcategory from a list of objects of class pixel_rule.

Usage

pixel_subcategory(subcat_name, ...)
is.subcategory(x)
# S3 method for pixel_subcategory
summary(object, ...)

Value

An object of class "pixel_subcategory", which is a list with these elements:

name a character string containing the name of the subcategory.
rules_list a list of pixel_rule objects.

Arguments

subcat_name: a character string containing the name of the subcategory.
...: in pixel_subcategory() a list of objects of class "pixel_rule"; in summary(), additional parameters (none needed by now).
x: the R object being tested
object: an object of class "pixel_subcategory".

Details

When the shape of the cluster of pixels belonging to one category is not convex, the rules become inconsistent (the lines cross in awkward ways) and the classification produced is erroneous. To solve this problem, the complete set of rules is divided into several subsets (subcategories) that break the original non-convex shape into a set of convex polygons. Note that any polygon can be divided in a number of triangles, so this problem always has solution. However, in many cases (such as the one presented in the pixelclasser vignette) a complete triangulation is not needed.

Internally, classify_pixels() classifies the points belonging to each subcategory and then joins the incidence matrices using the or operator, to create the matrix for the whole category.

Examples

Run this code

rule01 <- pixel_rule("R01", "g", "b",
                      list(c(0.35, 0.30), c(0.45, 0.10)), ">=")
rule02 <- pixel_rule("R02", "g", "b",
                      list(c(0.35, 0.253), c(0.45, 0.253)), ">=")

subcat01 <- pixel_subcategory("Subcat_01", rule01, rule02)