gps2traj is a command line tool to convert GPS data (each row is a point containing id, x, y, timestamp fields) to trajectory format (each row is a LineString/trip). Both input and output are in CSV format.

The tool will partition GPS points according to id field and sort by timestamp.

# Input
id,x,y,timestamp
1,0,0,3
1,0,1,2
1,1,1,1

# Output
index;id;geom
1;1;LineString(1 1,0 1,0 0)

Test on a CSV file with 30 million rows takes about 84.797 seconds.

• -i/--input: input file
• -o/--output: output file
• -d/--delim: delimiter character (default ,)
• --id: id column name (default id)
• -x/--x: x column name or index (default x)
• -y/--y: y column name or index (default y)
• -t/--time: timestamp column name or index (default timestamp)
• -f/--tf: timestamp format (default Unix timestamp, can be specified as strftime template)
• --no_header: if specified, gps file contains no header
• --time_gap: time gap to split too long trajectories (default 1e9)
• --dist_gap: distance gap to split too long trajectories (default 1e9)
• --ofields: output fields (ts,tend,timestamp) separated by , (default "")

https://en.cppreference.com/w/cpp/chrono/c/strftime

cd example
gps2traj -i gps.csv -o traj.csv --time_gap 10
gps2traj -i gps_semicolon.csv -o traj.csv --time_gap 10 -d ';'
gps2traj -i gps_no_header.csv -o traj_timestamp.csv --time_gap 10 --no_header --id 0 -x 2 -y 3 -t 1 --ofields ts,tend,timestamp
gps2traj -i gps_timestamp_format.csv -x lng -y lat -f "%Y-%m-%d %H:%M:%S" --ofields timestamp -o traj_format.csv

This tool transform a trajectory with linestring geometry into points.

# Input
id;geom
1;LineString(1 1,0 1,0 0)

# Output
id;point_idx;x;y
1;0;1;1
1;1;0;1
1;2;0;0

• -i/--input: input file
• -o/--output: output file
• -d/--delim: field delimiter character (default ;)
• --id: id column name (default id)
• -g/--geom: geom column name or index (default geom)
• --no_header: if specified, traj file contains no header

cd example
traj2gps -i traj_input.csv -o gps_output.csv

Run the command in bash shell at the project folder

make
make install

You may need root permission to run the second command sudo make install

• Unix environment
• C++11

Can Yang, Email: cyang(at)kth.se