Create a grid of time spent from an object of class trip by
approximating the time between locations for separate trip events.
tripGrid.interp(x, grid = NULL, method = "count", dur = NULL, ...)kdePoints(x, h = NULL, grid = NULL, resetTime = TRUE, ...)
countPoints(x, dur = 1, grid = NULL)
tripGrid returns an object of class SpatialGridDataFrame, with
one column "z" containing the time spent in each cell in seconds. If
kdePoints is used the units are not related to the time values and must be
scaled for further use.
object of class trip
GridTopology - will be generated automatically if NULL
name of method for quantifying time spent, see Details
The \"dur\"ation of time used to interpolate between available locations (see Details)
other arguments passed to interpequal or kdePoints
kernel bandwidth
rescale result back to the total duration of the input
This set of functions was the the original tripGrid from prior to version
1.1-6. tripGrid should be used for more exact and fast calculations
assuming linear motion between fixes.
The intention is for tripGrid.interp to be used for exploring
approximate methods of line-to-cell gridding.
Trip locations are first interpolated, based on an equal-time spacing
between records. These interpolated points are then "binned" to a grid of
cells. The time spacing is specified by the dur (duration) argument to
interpequal in seconds (i.e. dur=3600 is used for 1 hour).
Shorter time periods will require longer computation with a closer
approximation to the total time spent in the gridded result.
Currently there are methods "count" and "kde" for quantifying time spent, corresponding to the functions "countPoints" and "kdePoints". "kde" uses kernel density to smooth the locations, "count" simply counts the points falling in a grid cell.
bandwidth.nrd for the calculation of bandwidth values used internally when not supplied by the user