Description Details Gris features I. Creation II. Plotting III. Manipulation IV. Conversion to other types V. Miscellaneous Gris topology

The gris package provides a relational table model for **spatial vector** data in R. ** Spatial vector data**
are topology-based discrete spatial units such as areas (including polygons), lines and points.

These kinds of data are defined in many different ways in various R packages, but the `sp`

package has provided the most comprehensive and standard model to match the traditional GIS layer forms.

provide a clear decoupling of topology from geometry (see section "Gris topology" below)

transcend the X/Y-only limitation for vertex attributes

allow multiple topological types in individual layers (i.e. Manifold or MapInfo drawings)

provide a flexible basis for conversion between other formats and domain-specific structures

`gris.Spatial` | create from Spatial*DataFrame |

`grisFromRasterGeom` | create from `geom` format |

`grisFromFortify` | create from `fortify` format |

`as.gris.triangulation` | create from `triangulation` |

`plot.gris` | plot a gris object as polypath, lines, points, or triangles |

`plot3d.gris` | plot a gris object in 3d |

`[.gris` | extract a subset of a gris object |

`pointInTriangle` | identify which triangle points fall in |

`as.SpatialPolygonsDataFrame.gris` | coerce to SpatialPolygonsDataFrame, SpatialLinesDataFrame, SpatialPointsDataFrame, SpatialMultiPointsDataFrame |

`triangulate.gris` | add triangle primitives to a gris object |

`brick2col` | create hex value colours from an RGB `RasterBrick` |

Topology defines the way that space is filled by 0D (points), 1D (lines), 2D (areas - or polygons) objects. (Higher dimensional topologies are possible but not explored yet.)

Geometry defines an actual instantiation of an object in a given coordinate system.

Examples of the difference are

polygons defining continental outlines on the Earth, these shapes are 2D topologically, but geometrically can be plotted in the plane (in long-lat, or projected coordinates) or "draped" around a curve, such as the Earth as a globe or across a topographic landscape

lines defining animal tracks in space time, these 1D shapes can have

**geometric**vertex attributes such as X, Y, Z, time, temperature, etc.

Topology dimension may be 0D, 1D, 2D, or higher and geometry dimension is not necessarily coupled to this, or restricted to 2D.

Note that certain degeneracies are possible and may be important. A time series of point estimates in space may not have any sensible geometric values at all, but the topological description provided by that time series is a real structure.

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