◆ MAX_LENGTH_TRIP

#define MAX_LENGTH_TRIP 170001

A simple program that reads from a CSV file synthetic trip data in Brussels generated by the MobilityDB-BerlinMOD generator, https://github.com/MobilityDB/MobilityDB-BerlinMOD disassembles the trips into individual observations, and write them in a CSV file named "trip_instants.csv" ordered by timestamp.

The input file is

trips.csv: 55 trips from 5 cars during 4 days obtained from the generator at scale factor 0.005. The input file has been generated with the following SQL command on the database containing the generated data
COPY (SELECT tripid, vehid, day, seqno, ashexewkb(trip) AS trip FROM trips WHERE vehid < 6 ORDER BY tripid) TO '/home/user/src/trips.csv' CSV HEADER;

trips
CREATE TABLE trips(tripid int NOT NULL, vehid int NOT NULL, day date NOT NULL, seqno int NOT NULL, trip tgeompoint NOT NULL)

COPY
COPY(SELECT tripid, vehid, day, seqno, asHexEWKB(trip) AS trip FROM trips) TO '/home/esteban/src/MobilityDB/meos/examples/trips.csv' CSV HEADER

day
INSERT INTO trips SELECT day
Definition: meos_disassemble_berlinmod.txt:22

seqno
INSERT INTO trips SELECT seqno
Definition: meos_disassemble_berlinmod.txt:22

tripid
INSERT INTO trips SELECT tripid
Definition: meos_disassemble_berlinmod.txt:22

vehid
INSERT INTO trips SELECT vehid
Definition: meos_disassemble_berlinmod.txt:22

HEADER
COPY trip_instants FROM home esteban src MobilityDB meos examples trip_instants csv CSV HEADER
Definition: meos_disassemble_berlinmod.txt:11

In the above file, the coordinates are given in the 3857 coordinate system, https://epsg.io/3857 and the timestamps are given in the Europe/Brussels time zone. This simple program does not cope with erroneous inputs, such as missing fields or invalid values.

The program can be build as follows

gcc -Wall -g -I/usr/local/include -o 05_meos_disassemble_berlinmod 05_meos_disassemble_berlinmod.c -L/usr/local/lib -lmeos