drammock

library(phonR)  # convexHullArea
library(sp)     # SpatialPolygons, etc
library(rgeos)  # gIntersection
data(indoVowels)
female_two <- indo[indo$subj == "F02",]
by_vowel <- split(female_two, female_two$vowel)
hull_indices <- sapply(by_vowel, function(df) with(df, chull(f1, f2)))
hulls <- sapply(names(by_vowel), function(v) by_vowel[[v]][hull_indices[[v]],],
                simplify=FALSE)
matrices <- sapply(hulls, function(df) as.matrix(df[,c("f1", "f2")]))