Dear, I am trying to plot contours (with filled.contour function) inside UK area, so that no contours are plotted over the sea. I was wondering if anyone can help me with this task and if I can get any suggestions how to do that. Thank you, Irina Irina Foss Environmental Research Institute North Highland College UHI Millennium Institute Castle Street Thurso, Caithness Scotland KW14 7JD United Kingdom Tel: +44 (0) 1847 889 587 Fax: +44 (0) 1847 890 014 http://www.eri.ac.uk/sub/staff.php?id=11
Plot contour inside a polygon
2 messages · Irina Foss, Duncan Murdoch
On 3/20/2009 8:40 AM, Irina Foss wrote:
Dear, I am trying to plot contours (with filled.contour function) inside UK area, so that no contours are plotted over the sea. I was wondering if anyone can help me with this task and if I can get any suggestions how to do that.
If you have a grid of values over a larger area than the UK, set the values outside the UK to NA, then contour won't draw contours there. For example, to get contours only in the circle x^2 + y^2 < 1: x <- seq(-1, 1, len=100) y <- seq(-1, 1, len=100) z <- outer(x, y, function(x,y) ifelse(x^2 + y^2 < 1, sin(x)+cos(y), NA)) contour(x,y,z) theta <- seq(0, 2*pi, len=256) lines(cos(theta), sin(theta)) The maps package contains map.where() to say what region a particular grid point is in; just check that it's a UK region. Duncan Murdoch