A partial component of
ddfilter, although works as a stand-alone function.
This function removes locations by a given threshold speed as described in Shimada et al. (2012).
A data frame containing columns with the following headers: "id", "DateTime", "lat", "lon", "qi".
See the data
A numeric value specifying a threshold of speed from a previous and/or to a subsequent fix.
Default is 8.9km/h.
If this value is unknown, it can be estimated from sdata using the function
An integer specifying how locations should be filtered with vmax. A location is removed if the speed from a previous and(1)/or(2) to a subsequent location exceeds vmax. Default is 1 (both way).
This function removes locations if the speed from a previous and/or to a subsequent location exceeds a given threshold speed.
If vmax is unknown, it can be estimated using the function
The input data is returned without locations identified by this filter. The following columns are added: "pTime", "sTime", "pDist", "sDist", "pSpeed", "sSpeed". "pTime" and "sTime" are hours from a previous and to a subsequent fix respectively. "pDist" and "sDist" are straight distances in kilometres from a previous and to a subsequent fix respectively. "pSpeed" and "sSpeed" are linear speed from a previous and to a subsequent fix respectively.
Shimada T, Jones R, Limpus C, Hamann M (2012) Improving data retention and home range estimates by data-driven screening. Marine Ecology Progress Series 457:171-180 doi: 10.3354/meps09747
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