[R] overlaying a levelplot on a map plot

[David Winsemius]

On Apr 22, 2010, at 2:24 PM, Kevin Wright wrote:

> Mixing base/lattice graphics can be tricky, but is possible.
>
> http://www.bioconductor.org/CRAN/web/packages/gridBase/vignettes/gridBase.pdf

That could be quite useful in the future. Thanks for that.

>
> Also, did you look at Chapter 13 of the lattice book?
> http://lmdvr.r-forge.r-project.org/figures/figures.html

I did look at the actual book, and upon doing so yet again, I would  
say that my comments were an accurate, if pithy, summary of the  
message I take away from what very little regarding base graphics  
appears in that chapter.

-- 
David.

>
> Kevin
>
> On Wed, Apr 21, 2010 at 2:08 PM, David Winsemius <dwinsemius at comcast.net 
> > wrote:
>
> On Apr 21, 2010, at 2:27 PM, Simon Goodman wrote:
>
>>> I've generated a levelplot showing the density distribution of a  
>>> species
>>> derived from survey transects, with lon, lat co-ordinates.
>>>
>>> I'd like to overlay this on a map of the study region specified by:
>>>
>>> map('worldHires', xlim = range(mlon), ylim = range(mlat)), where  
>>> mlon, mlat
>>> specifies the study region.
>>>
>>> > ?map
>>> No documentation for 'map' in specified packages and libraries:
>>> you could try '??map'
>>> > ??map
>>> > require(maps)
>>> Loading required package: maps
>>> > map
>>
>> So map uses base graphics.
>
>
>>> I've tried plotting the map first, then using the options:  
>>> 'add=TRUE,
>>> axes=FALSE' in the levelplot,
>>
>
>> levelplot is a lattice function. You will have failure with most  
>> efforts to mix base and grid graphics.
>
>>> but this doesn't work - a new plot is
>>> generated for the level plot despite the 'add' option. If I try to  
>>> add the
>>> map on top of the level plot, they are not to the same scale.
>>>
>>> Any suggestions on how to get round this.
>>>
>>> Thanks
>>
> -- 

David Winsemius, MD
West Hartford, CT