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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::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. A vector of GTFS shape_ids to pull. 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 <- "804EB_RC_221121"
my_crs = 32611

# Get shape from WMATA GTFS
lineE_shape <- get_shape_geometry(gtfs = lacmta_gtfs,
                                  shape = my_shape,
                                  project_crs = my_crs)
print(lineE_shape)
#> Simple feature collection with 1 feature and 1 field
#> Geometry type: MULTILINESTRING
#> Dimension:     XY
#> Bounding box:  xmin: 362276 ymin: 3764673 xmax: 393555.7 ymax: 3768928
#> Projected CRS: WGS 84 / UTM zone 11N
#> # A tibble: 1 × 2
#>   shape_id                                                              geometry
#>   <chr>                                                    <MULTILINESTRING [m]>
#> 1 804EB_RC_221121 ((362276 3764673, 362291.9 3764699, 362324.6 3764751, 362332.…