I'm not too familiar with the lattice/grid graphic model, and thus their
implementation for spatial plotting is new to me also.  I know that
spplot() in the sp package can probably do what I need, but I would
appreciate advice.

I have fishing catch data by quarters (4 season) and years (2000-2010). I
would like to plot maps (including a land coastline) of the total catch for
each 1x1 grid cell (sum of catches in each grid cell) by season and year,
using color to represent the catch.  So I should end up with 40 maps (4
seasons per year x 10 years).  Below is a simulated dataset.

# simulated data
spat.dat<-data.frame(Quarter=round(runif(500, min=1, max=4)),
                     Year=round(runif(500, min=2000, max=2009)),
                     Longitude=round(runif(500, min=235, max=250)),
                     Latitude=round(runif(500, min=10, max=40)),
                     Catch=rpois(n=500, lambda=c(0, 3)))

Is it simpler to do an operation (ie. sum, average, etc.) on each grid
cell with call to a lattice-style formula than to write my own loop over
the dataset to do this kind of summary and then plot?  I'm stumped on
summarizing the grid cells, and also not sure how to include the
land/coastline data as well

Thank you,

Tim

	[[alternative HTML version deleted]]

