Tom, 
The sub argument will always put text at the bottom -- this is all plotting in R not just image.plot
If you want two lines in the title just build in a new line:

z<- outer( 1:15, 1:10,"+")
 image.plot( z, main="the title \n the subtitle")

Best, 
Doug

 
----------------------------------------------------------------------------- 
Doug Nychka,    

Institute for Mathematics Applied to Geosciences
National Center for Atmospheric Research 
Boulder, CO                     
Email: nychka "AT" ucar "DOT" edu  Web: www.image.ucar.edu/~nychka
Voice: 303-497-1711     FAX: 303-497-1298   Business Cell: 303-725-3199


On May 1, 2012, at 10:25 AM, Tom Roche wrote:

> 
> summary: how to make image.plot print a subtitle between the title and
> the image, rather than under the image?
> 
> details:
> 
> I've got a project
> 
> https://github.com/TomRoche/ioapi-hack-R
> 
> that illustrates the use of (et al) the R packages {ncdf4, fields, M3}
> for processing and visualizing IOAPI data. The data being visualized
> consists of a series of layers (mostly representing emissions from a
> particular tuple of agricultural {cultivar, cultivation technique})
> over a surface (in the upper midwest US). I'm currently plotting
> 
> https://github.com/downloads/TomRoche/ioapi-hack-R/compare.DN2.layers.pdf
> 
> each layer, and including some information about the layer in a title
> and subtitle. The title is where I want it--above the image--but the
> subtitle is printing below the image; I'd prefer it between the title
> and the image. Can this be done? FWIW, the code that plots (in
> 
> https://github.com/TomRoche/ioapi-hack-R/blob/master/plotLayersForTimestep.r
> 
> ) is like
> 
>  if (data to plot is not all NA) {
>    # determine quantiles, then
>    image.plot(plot.list, xlab="", ylab="", axes=F, col=colors(100),
>      axis.args=list(at=quantiles, labels=quantiles.formatted),
>      main=title, sub=subtitle)
>    lines(map)
>  } else {
>    plot(0, type="n", axes=F, xlab="", ylab="",
>      xlim=range(x.centers), ylim=range(y.centers),
>      main=title, sub=subtitle)
>    lines(map)
>  } # end testing data
> 
> TIA, Tom Roche <Tom_Roche@pobox.com>


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