Title:	Geometry Decomposition
Version:	0.4.0
Description:	Build a map of path-based geometry, this is a simple description of the number of parts in an object and their basic structure. Translation and restructuring operations for planar shapes and other hierarchical types require a data model with a record of the underlying relationships between elements. The gibble() function creates a geometry map, a simple record of the underlying structure in path-based hierarchical types. There are methods for the planar shape types in the 'sf' and 'sp' packages and for types in the 'trip' and 'silicate' packages.
Depends:	R (≥ 3.3.0)
License:	GPL-3
Encoding:	UTF-8
LazyData:	true
RoxygenNote:	7.1.0
Imports:	dplyr, methods, tibble, rlang
Suggests:	covr, testthat, knitr, rmarkdown
URL:	https://github.com/mdsumner/gibble
BugReports:	https://github.com/mdsumner/gibble/issues
VignetteBuilder:	knitr
NeedsCompilation:	no
Packaged:	2020-05-09 03:08:04 UTC; mdsumner
Author:	Michael Sumner [aut, cre]
Maintainer:	Michael Sumner <mdsumner@gmail.com>
Repository:	CRAN
Date/Publication:	2020-05-09 05:40:03 UTC

gibble package

Description

Path-based geometry decomposition to data frame.

Details

The goal of gibble is to provide a straightforward map of path-based data structures. Paths are connected linear sequences of coordinates, otherwise known as lines. Structured spatial data includes objects composed of paths, which are islands, holes within island, lines, and points. Polygons require an extra grouping level subobject to ensure holes are nested within their island, but this is ignored for other types.

Sequential inear structures are not optimal for many operations when working with spatial data, and gibble provides a simple bridge between existing paths and tools to decompose them to primitives.

Path-based geometry decomposition

Description

A gibble is a geometry map, a summary of the structure of each path within a simple planar shape. The generic function gibble() will summarize all paths within a complex type with a data frame row for each. Each row of the gibble summary represents a component element of the object's geometry and records the number of rows (i.e. how many coordinates) and the number of columns (i.e. the number of axes in the geometric space). Another column type records the class of the object, and object records an identifier for the entire object. A special case column subobject identifies the component POLYGON part within a MULTIPOLYGON. I.e. subobject is 1 unless that part is a hole. All identifiers are sequential within the higher level groupings.

Usage

## S3 method for class 'POINT'
gibble(x, ...)

## S3 method for class 'MULTIPOINT'
gibble(x, ...)

## S3 method for class 'LINESTRING'
gibble(x, ...)

## S3 method for class 'MULTILINESTRING'
gibble(x, ...)

## S3 method for class 'POLYGON'
gibble(x, ...)

## S3 method for class 'MULTIPOLYGON'
gibble(x, ...)

## S3 method for class 'list'
gibble(x, ...)

## S3 method for class 'sfc'
gibble(x, ...)

## S3 method for class 'sf'
gibble(x, ...)

## S3 method for class 'PATH0'
gibble(x, ...)

## S3 method for class 'PATH'
gibble(x, ...)

## S3 method for class 'trip'
gibble(x, ...)

## S3 method for class 'Polygon'
gibble(x, ...)

## S3 method for class 'Polygons'
gibble(x, ...)

## S3 method for class 'SpatialPolygons'
gibble(x, ...)

## S3 method for class 'Line'
gibble(x, ...)

## S3 method for class 'Lines'
gibble(x, ...)

## S3 method for class 'SpatialLines'
gibble(x, ...)

## S3 method for class 'SpatialMultiPoints'
gibble(x, ...)

## S3 method for class 'SpatialPoints'
gibble(x, ...)

## S3 method for class 'Spatial'
gibble(x, ...)

gibble(x, ...)

## Default S3 method:
gibble(x, ...)

Arguments

Details

Methods are provided for the sf classes. There is an internal version that is designed to work fast on sets of structures, by delaying conversion to list or data frame for as late as possible.

A geometry map is not so helpful on its own, and so does not have a formal class. It is designed for use within other workflows such as updating the coordinates of model object or translating between superficially different formats.

Gibble is a distillation of the sc_path encoding of package silicate, which came from the map_table decompositions of spbabel, as an improvement on the single-table fortify model used in ggplot2.

Value

data frame summarizing the geometry map, see Details

Examples

gibble(minimal_mesh)

hsh, home sweet home

Description

A testing data set, a list of poly, line, points. The relationships between the objects cover many interesting cases. There are multi-island objects with holes and other objects that fall inside those holes. All paths share vertices with a neighbour. There is topological intersection along a diagonal line where two objects meet and are joined by shared vertices that were inserted deliberately.

Details

hsh_sf is the holey home in sf format.

minimal mesh

Description

A testing data set, minimal_mesh composed of two MULTIPOLYGONs sharing one edge.

mpoly

Description

A testing data set, composed of two MULTIPOLYGONs, one is the manually constructed example from sf (and silicate::sfzoo$multipolygon), the second is South Australia, with many lake-islands in the main polygon, and one artifical hole in the Kangaroo Island polygon.