Description Usage Arguments Details Value References See Also Examples

Direction (in the linear motion model) and density of the direction distribution (in the BBMM) over specific time intervals.

1 2 3 | ```
direction(tr, time, time.scale = NA)
ddirection(d, tr, time, time.scale = NA)
pdirection(d, tr, time, time.scale = NA, lower = 0)
``` |

`tr` |
The trajectory object |

`time` |
A vector of times at which to report the direction |

`time.scale` |
The length of the intervals over which to report the direction |

`d` |
The direction for which to compute the density |

`lower` |
The lower end of the interval for the CDF |

The direction at a time *t* is defined as the direction of the net displacement over the time interval *[t-time.scale/2, t+time.scale/2]*. Directions are in radians from the positive *x* axis.

Since direction has a circular distribution, the distribution function has to be computed with respect to some base value. Using the `lower`

argument, one can change this base value. Thus, when calling `ddirection(x, ..., lower=l)`

, the density function will be integrated from `l`

to `x`

. The latter may be a vector.

`direction`

returns a matrix indexed by the ID in the trajectory and time.
`ddirection`

returns an array indexed by ID, the requested direction and time.

Buchin, K., Sijben, S., Arseneau, T. J. M., AND Willems, E. P.
Detecting movement patterns using brownian bridges. *In Proceedings of
the 20th International Conference on Advances in Geographic Information
Systems*, 119–128.

1 2 3 4 5 6 7 8 | ```
data("vervet_monkeys", package="moveBB")
## Compute the (linear model) direction over two half-hour intervals
#d <- direction(monkey.tr, as.POSIXct(c("2011-01-18 15:15:15", "2011-01-19 16:30:00")), 1800)
#d
## Compute the density of four directions over the same time intervals
#ddirection(d, monkey.tr, as.POSIXct(c("2011-01-18 15:15:15", "2011-01-19 16:30:00")), 1800)
``` |

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