[R] help: how to plot a circle on the scatter plot

[wu sz]

Hello,

I have a data set with 15 variables, and use "pairs" to plot the
scatterplot of this data set. Then I want to plot some circles on the
small pictures with high correlation(e.g. > 0.9).

First, I use "cor" to obtain the corresponding correlation matrix (x)
for this scatterplot.

Second, use "seq(along = x)[x > 0.9]" to find the positions of the
small pictures with 0.9 correlation, but "seq" can just find the
sequence position row by row for the matrix, not a real position (like
"rowNumber, colNumber"). Is any function for that?

Third, use "Symbols" to plot the circle on these small pictures, but
seems it can't do that. Also, I don't know how to adjust the thickness
and radius of the circle plotted by "Symbols".

Please give me some ideas!

Thank you,
Shengzhe