Generate a grid of time spent by line-to-cell gridding

Create a grid of time spent from an object of class trip by exact cell crossing methods, weighted by the time between locations for separate trip events.

tripGrid(x, grid = NULL, method = "pixellate", ...)

Arguments

x	object of class trip
grid	GridTopology - will be generated automatically if NULL
method	pixellate or density
...	pass arguments to density.psp if that method is chosen (and temporary mechanism to direct users of legacy methods to tripGrid.interp)

Value

tripGrid returns an object of class SpatialGridDataFrame, with one column "z" containing the time spent in each cell in seconds.

Details

Zero-length lines cannot be summed directly, their time value is summed by assuming the line is a point. A warning used to be given, but as it achieved nothing but create confusion it has been removed. The density method returns proportionate values, not summed time durations.

See pixellate.psp and pixellate.ppp for the details on the method used. See density.psp for method="density".

Trip events are assumed to start and end as per the object passed in. To work with inferred "cutoff" positions see split.trip.exact.