[R] How to map points to a fixed points position, then draw contours to the mapped points?

[vod vos]

Hello,

How to map points to a fixed points position, then draw contours to the mapped points?

A data frame like this:

r <- rep(seq(0,3.8,0.2), 256)

PI257 <- seq(0,360,360/256)
PI256 <- PI257[-257]
PI25631 <- rep(PI256, 20)

El <- rnorm(5120, mean = 42, sd = 4)

xyz <- data.frame(r, PI25631, EI)

How to map y points to the fixed position defined by x and y in a polar system,
using R base plot functions or ggplot2 (aes mapping) to achieve a similar figure like the link:

https://www.clspectrum.com/archive/2009/October/images/CLS_October_A10_Fig04.jpg

Sincerely yours,
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