Assemble Example

This example demonstrates how to:

  • Read in points using Tracktable’s C++ command line factories

  • Assemble points into trajectories

  • Write trajectories out to a file for later uses

The full assemble example source code can be found in the Tracktable source code distribution in the directory tracktable/Examples and the example can be executed by calling the assemble program from the command line provided that the example is built and it’s location is exposed to the appropriate system path. Below you will find the execution command for the example as well as the source files in there entirety for quick reference.

Example Source Files

The page listed here contains a direct import of the source code for this example. This is provided for convenience and reference.

Command Line Interface

Note

This command is specific to Linux and Mac. Windows machines will have a different command line call.

The command to run the assemble example is as follows.

Typical Command
$ ./assemble --input=/data/flights.tsv --output=/data/flights.trj

This command takes an input parameter of a tab separated value or comma seperated value file formatted as OBJECTID TIMESTAMP LON LAT of points to assemble and an output parameter of a tracjectory file for the assembled trajectories.

Note

The default delimiter is tab, if you are using a CSV file you will need to set the --delimiter parameter. The default output is standard out unless a --output file is specified.

The command line interface contains a --help option that will display all of the possible switches for the example.

$ ./assemble --help

will display:

--help                            Print help
--output arg (=-)                 file to write to (use '-' for stdout),
                                     overridden by 'separate-kmls'

Point Reader:
 --input arg (=-)                  Filename for input (use '-' for standard
                                     input)
 --real-field arg                  Field name and column number for a
                                     real-valued point field
 --string-field arg                Field name and column number for a string
                                     point field
 --timestamp-field arg             Field name and column number for a
                                     timestamp point field
 --object-id-column arg (=0)       Column containing object ID for points
 --timestamp-column arg (=1)       Column containing timestamp for points
 --x-column arg (=2)               Column containing X / longitude coordinate
 --y-column arg (=3)               Column containing Y / latitude coordinate
 --delimiter arg (=    )           Delimiter for fields in input file

Assembler:
 --separation-distance arg (=100)  Set maximum separation distance for
                                     trajectory points
 --separation-seconds arg (=1200)  Set maximum separation time (in seconds)
                                     for trajectory points
 --min-points arg (=10)            Trajectories shorter than this will be
                                     discarded
 --clean-up-interval arg (=10000)  Number of points between cleanup