gtfs-via-postgres/lib/shapes.js

Process GTFS using PostgreSQL.

'use strict'

// https://gtfs.org/documentation/schedule/reference/#shapestxt
const beforeAll = (opt) => `\
CREATE TABLE "${opt.schema}".shapes (
	id SERIAL PRIMARY KEY,
	shape_id TEXT,
	shape_pt_sequence INT,
	shape_pt_loc geography(POINT),
	shape_dist_traveled REAL
);

COPY "${opt.schema}".shapes (
	shape_id,
	shape_pt_loc,
	shape_pt_sequence,
	shape_dist_traveled
) FROM STDIN csv;
`

const formatShapesRow = (s) => {
	return [
		s.shape_id || null,
		`POINT(${parseFloat(s.shape_pt_lon)} ${parseFloat(s.shape_pt_lat)})`,
		s.shape_pt_sequence ? parseInt(s.shape_pt_sequence) : null,
		s.shape_dist_traveled ? parseInt(s.shape_dist_traveled) : null,
	]
}

const afterAll = (opt) => `\
\\.

CREATE INDEX shapes_by_shape_id ON "${opt.schema}".shapes (shape_id);
CREATE INDEX ON "${opt.schema}".shapes (shape_id, shape_pt_sequence);

CREATE OR REPLACE VIEW "${opt.schema}".shapes_aggregated AS
SELECT
	shape_id,
	array_agg(shape_dist_traveled) AS distances_travelled,
	-- todo [breaking]: make this a geography!
	ST_MakeLine(array_agg(shape_pt_loc)) AS shape
FROM (
	SELECT
		shape_id,
		shape_dist_traveled,
		ST_AsText(shape_pt_loc)::geometry AS shape_pt_loc
	FROM "${opt.schema}".shapes
	ORDER by shape_id, shape_pt_sequence
) shapes
GROUP BY shape_id;

${opt.postgraphile ? `\
COMMENT ON TABLE "${opt.schema}".shapes IS E'@omit';
COMMENT ON COLUMN "${opt.schema}".shapes.id IS E'@omit';
COMMENT ON VIEW "${opt.schema}".shapes_aggregated IS E'@name shapes\\n@primaryKey shape_id';
` : ''}
`

module.exports = {
	beforeAll,
	formatRow: formatShapesRow,
	afterAll,
}