gtfs_gleam - v1.0.0

gtfs/common/geo

Geographic Utilities

Provides geographic calculations for GTFS data including:

Example

import gtfs/common/geo
import gtfs/common/types.{Coordinate}

pub fn main() {
  let nyc = Coordinate(40.7128, -74.0060)
  let la = Coordinate(34.0522, -118.2437)

  let km = geo.distance_km(nyc, la)
}

Values

bearing

</> 
pub fn bearing(
  from: types.Coordinate,
  to: types.Coordinate,
) -> Float

Calculate the initial bearing from one coordinate to another. Returns bearing in degrees (0-360, where 0 is north).

bounding_box

</> 
pub fn bounding_box(
  coords: List(types.Coordinate),
) -> Result(#(types.Coordinate, types.Coordinate), String)

Calculate the bounding box for a list of coordinates

decode_polyline

</> 
pub fn decode_polyline(
  encoded: String,
) -> Result(List(types.Coordinate), String)

Decode a Google encoded polyline string into a list of coordinates. Used for GTFS Realtime shapes and static shapes.txt visualization.

distance_km

</> 
pub fn distance_km(
  from: types.Coordinate,
  to: types.Coordinate,
) -> Float

Calculate the great-circle distance between two coordinates using the Haversine formula. Returns distance in kilometers.

distance_m

</> 
pub fn distance_m(
  from: types.Coordinate,
  to: types.Coordinate,
) -> Float

Calculate the great-circle distance between two coordinates using the Haversine formula. Returns distance in meters.

encode_polyline

</> 
pub fn encode_polyline(coords: List(types.Coordinate)) -> String

Encode a list of coordinates into a Google encoded polyline string.

is_valid_coordinate

</> 
pub fn is_valid_coordinate(coord: types.Coordinate) -> Bool

Check if a coordinate is valid (within WGS84 bounds)

point_in_polygon

</> 
pub fn point_in_polygon(
  point: types.Coordinate,
  polygon: List(types.Coordinate),
) -> Bool

Check if a coordinate is inside a polygon using the ray casting algorithm. The polygon is defined as a list of coordinates forming a closed ring.

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