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Get the geometry of a route shape.

Source: R/gtfs_helpers.R
get_shape_geometry.Rd

This function returns an SF multilinestring of the route alignments from GTFS shapes. Similar to tidytransit's get_geometry(), but allows filtering by shape_id and projection to a new coordinate system. See Details for requirements on the input GTFS.

Usage

get_shape_geometry(gtfs, shape = NULL, project_crs = 4326)

Arguments

gtfs

A tidygtfs object.

shape

Optional. The GTFS shape_id to use. Can be a single value, or a vector. Default is NULL, where all shape_ids in gtfs will be used.

project_crs

Optional. A numeric EPSG identifer indicating the coordinate system to use for spatial calculations. Consider setting to a Euclidian projection, such as the appropriate UTM zone. Default is 4326 (WGS 84 ellipsoid).

Value

An SF multilinestring, with one multilinestring object per shape_id.

Details

A shapes file must be present in your GTFS object. This file must contain at least the following fields:

  • shape_id

  • shape_pt_lat

  • shape_pt_lon

  • shape_pt_sequence

Examples

# Set my parameters
my_shape <- "C53:04"
my_crs = 32618

# Get shape from WMATA GTFS
c53_shape <- get_shape_geometry(gtfs = wmata_gtfs,
                                shape = my_shape,
                                project_crs = my_crs)
print(c53_shape)
#> Simple feature collection with 1 feature and 1 field
#> Geometry type: MULTILINESTRING
#> Dimension:     XY
#> Bounding box:  xmin: 322061.8 ymin: 4301418 xmax: 329233.3 ymax: 4310353
#> Projected CRS: WGS 84 / UTM zone 18N
#> # A tibble: 1 × 2
#>   shape_id                                                              geometry
#>   <chr>                                                    <MULTILINESTRING [m]>
#> 1 C53:04   ((327507.1 4301484, 327505.6 4301478, 327504.9 4301473, 327504 43014…