| markextremes | R Documentation | 
Adjusts the proportion of extreme points to be labeled to the number of
observations. It is the default of the ploption markextremes. 
markextremes(n)
n | 
 number of observations  | 
The function simply applies ceiling(sqrt(n)/2)/n.
A scalar between 0 and 0.5
Werner A. Stahel
markextremes(20)
for (n in c(10,20,50,100,1000))  print(c(n,markextremes(n)))
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