[R] plot 4th variable contour lines on filled.contour

[AnaFilipaDeMouraQueiros]

Hello,
I have a dataset with 4 variables, each consisting of a vector, all with 
the same length. I start by interpolating the first three variables 
using the function "interp", and plot the interpolation successfully 
using "filled.contour". I then interpolate the first two variables and a 
fourth using "interp" again, but when I try to overlay the  contour 
lines of this second interpolation on the first filled.contour plot, the 
lines appear to be located wrongly on the plot, overlapping the colour bar!
Any light shed on this matter would be most appreciated..
Kind regards
Ana
de Moura Queiros,Ana Filipa         osp402 at bangor.ac.uk

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