# s2_options: Geography Operation Options In s2: Spherical Geometry Operators Using the S2 Geometry Library

## Description

These functions specify defaults for options used to perform operations and construct geometries. These are used in predicates (e.g., `s2_intersects()`), and boolean operations (e.g., `s2_intersection()`) to specify the model for containment and how new geometries should be constructed.

## Usage

 ``` 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22``` ```s2_options( model = NULL, snap = s2_snap_identity(), snap_radius = -1, duplicate_edges = FALSE, edge_type = "directed", validate = FALSE, polyline_type = "path", polyline_sibling_pairs = "keep", simplify_edge_chains = FALSE, split_crossing_edges = FALSE, idempotent = FALSE, dimensions = c("point", "polyline", "polygon") ) s2_snap_identity() s2_snap_level(level) s2_snap_precision(precision) s2_snap_distance(distance) ```

## Arguments

 `model` One of 'open', 'semi-open' (default for polygons), or 'closed' (default for polylines). See section 'Model' `snap` Use `s2_snap_identity()`, `s2_snap_distance()`, `s2_snap_level()`, or `s2_snap_precision()` to specify how or if coordinate rounding should occur. `snap_radius` As opposed to the snap function, which specifies the maximum distance a vertex should move, the snap radius (in radians) sets the minimum distance between vertices of the output that don't cause vertices to move more than the distance specified by the snap function. This can be used to simplify the result of a boolean operation. Use -1 to specify that any minimum distance is acceptable. `duplicate_edges` Use `TRUE` to keep duplicate edges (e.g., duplicate points). `edge_type` One of 'directed' (default) or 'undirected'. `validate` Use `TRUE` to validate the result from the builder. `polyline_type` One of 'path' (default) or 'walk'. If 'walk', polylines that backtrack are preserved. `polyline_sibling_pairs` One of 'discard' (default) or 'keep'. `simplify_edge_chains` Use `TRUE` to remove vertices that are within `snap_radius` of the original vertex. `split_crossing_edges` Use `TRUE` to split crossing polyline edges when creating geometries. `idempotent` Use `FALSE` to apply snap even if snapping is not necessary to satisfy vertex constraints. `dimensions` A combination of 'point', 'polyline', and/or 'polygon' that can used to constrain the output of `s2_rebuild()` or a boolean operation. `level` A value from 0 to 30 corresponding to the cell level at which snapping should occur. `precision` A number by which coordinates should be multiplied before being rounded. Rounded to the nearest exponent of 10. `distance` A distance (in radians) denoting the maximum distance a vertex should move in the snapping process.

## Model

The geometry model indicates whether or not a geometry includes its boundaries. Boundaries of line geometries are its end points. OPEN geometries do not contain their boundary (`model = "open"`); CLOSED geometries (`model = "closed"`) contain their boundary; SEMI-OPEN geometries (`model = "semi-open"`) contain half of their boundaries, such that when two polygons do not overlap or two lines do not cross, no point exist that belong to more than one of the geometries. (This latter form, half-closed, is not present in the OpenGIS "simple feature access" (SFA) standard nor DE9-IM on which that is based). The default values for `s2_contains()` (open) and covers/covered_by (closed) correspond to the SFA standard specification of these operators.

## Examples

 ```1 2 3``` ```# use s2_options() to specify containment models, snap level # layer creation options, and builder options s2_options(model = "closed", snap = s2_snap_level(30)) ```

s2 documentation built on June 17, 2021, 5:11 p.m.