Hi,
Sorry if this is already known...
contour() sometimes draws contour lines that intersect. Is there a temporary fix?
A dataset which causes problems is at http://www.maths.uwa.edu.au/~adrian/dumpdata.R If you try just source("dumpdata.R") image(huh) contour(huh) the 100 x 100 matrix 'huh' contains an hourglass-shaped region of values around 0.8. The contour plot shows two contour lines at the level 0.8 which cross each other in a figure 8.
In the short term can anyone suggest how to fix the contour plot for this particular dataset??
A close look suggests that the lines don't actually cross -- e.g. try
contour(huh, xlim = c(0.82, 0.88), ylim = c(0.1, 0.12))
The handling of the "crossing case" in R is an implementation of that in Cleveland's "Visualizing Data" (one of the "for-the-record" sections). I don't think the algorithm permits crossings.
-- Ross Ihaka Email: [EMAIL PROTECTED] The R Project and R Foundation
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