gps2traj

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.

Usage of gps2traj

• -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

Run example

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

traj2gps

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

Usage of traj2gps

• -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

Run example

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

Build and install

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

Dependency

• Unix environment
• C++11

Contact

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