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Filter a GTFS object using a spatial extent

Source: R/filter_by_spatial_extent.R
filter_by_spatial_extent.Rd

Filters a GTFS object using a spatial extent (passed as an sf object), keeping (or dropping) entries related to shapes and trips whose geometries are selected through a specified spatial operation.

Usage

filter_by_spatial_extent(
  gtfs,
  geom,
  spatial_operation = sf::st_intersects,
  keep = TRUE
)

Arguments

gtfs

A GTFS object, as created by read_gtfs().

geom

An sf object. Describes the spatial extent used to filter the data.

spatial_operation

A spatial operation function from the set of options listed in geos_binary_pred (check the DE-I9M Wikipedia entry for the definition of each function). Defaults to sf::st_intersects, which tests if the shapes and trips have ANY intersection with the object specified in geom. Please note that geom is passed as the x argument of these functions.

keep

A logical. Whether the entries related to the shapes and trips selected by the given spatial operation should be kept or dropped (defaults to TRUE, which keeps the entries).

Value

The GTFS object passed to the gtfs parameter, after the filtering process.

See also

Other filtering functions: filter_by_agency_id(), filter_by_route_id(), filter_by_route_type(), filter_by_service_id(), filter_by_sf(), filter_by_shape_id(), filter_by_stop_id(), filter_by_time_of_day(), filter_by_trip_id(), filter_by_weekday()

Examples

data_path <- system.file("extdata/spo_gtfs.zip", package = "gtfstools")
gtfs <- read_gtfs(data_path)

shape_id <- "68962"
shape_sf <- convert_shapes_to_sf(gtfs, shape_id)
bbox <- sf::st_bbox(shape_sf)
object.size(gtfs)
#> 860808 bytes

# keeps entries that intersect with the specified polygon
smaller_gtfs <- filter_by_spatial_extent(gtfs, bbox)
object.size(smaller_gtfs)
#> 324952 bytes

# drops entries that intersect with the specified polygon
smaller_gtfs <- filter_by_spatial_extent(gtfs, bbox, keep = FALSE)
object.size(smaller_gtfs)
#> 512288 bytes

# uses a different function to filter the gtfs
smaller_gtfs <- filter_by_spatial_extent(
  gtfs,
  bbox,
  spatial_operation = sf::st_contains
)
object.size(smaller_gtfs)
#> 68976 bytes