ptrackr: ptrackr: a package to track individual particles through 2D-...

In janjansen86/ptrackr: Tracking Individual Particles Through 2D- and 3D-Space

Description

The ptrackr package intends to provide the basic functions needed to store the positions and track the movement of individual particles through time and space. The package is written in the context of movement of particles in a velocity field taken from a Regional Oceanographic Modelling System (ROMS). The main function to run particle-tracking is called "loopit_2D3D" (examples are provided below), with the other functions either being called from the main function or serving to setup the data for the modelling. More details can be found in the individual desription files.

overview

The package is setup into 3 main functions. The functions that do the actual tracking of the particles are trackit_2D and trackit_3D for 2D and 3D respectively. These two functions work with user-specified time-steps (e.g. 30min) at which the current position of each particle and their movement during the next time-steps gets evaluated. The function loopit_2D3D loops one of the two trackit-functions over given time-intervalls (e.g. 6h, so in this example one loop of 6h with 30min time-steps would result in 12 rounds per loop). The advantage is that at the end of each loop those particles that have met a stopping criteria can be excluded from further loops, thereby greatly increasing the speed of the model-run.

basic 2D-example

data(surface_chl); data(toyROMS)

pts_seeded <- create_points_pattern(surface_chl, multi=100)

run <- loopit_2D3D(pts_seeded = pts_seeded, roms_slices = 4, romsobject = toyROMS, speed = 100, runtime = 50, sedimentation = TRUE)

plot(pts_seeded); points(run$pend, col="red", cex=0.6); points(run$pts , col="blue", cex=0.6)

legend("bottomleft", pch=1, pt.cex=c(1,0.6,0.6), col=c("black","red","blue"), legend=c("seed-location","end-location","still moving"))

Authors

Jan Jansen & Michael D. Sumner

Maintainer: Jan Jansen - Jan.Jansen(AT)utas.edu.au

DOI: 10.5281/zenodo.583336

URL: www.github.com/janjansen86/ptrackr

janjansen86/ptrackr documentation built on May 18, 2019, 2:38 p.m.