[R] how to overlay a map of US on image plot

[Jannis]

A First guess would be to have a look at ?map and change the 'add' 
argument to TRUE. This would overlay the map to the image plot that you 
produced before. It may be that you need to mess around with different 
projections etc. but I can not give you any advice on that without 
digging deep into the documentation....


HTH
Jannis

On 02/14/2011 03:14 AM, cassie jones wrote:
> Dear all,
>
> I have a data set which has latitude, longitude (not in increasing order)
> and observed precipitation corresponding to those locations. I am using
> image.plot command for that. But I want to overlay a map of US on that plot.
> I know we can use map('usa') to draw it, but I dont know how can I overlay
> it on the plot of the precipitation data. Can anyone please help me with it?
>
>
> Thanks in advance.
>
> Cassie.
>
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>
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