“Formal argument ”foo“ matched by multiple arguments” - how to deal with this in R?

Question

Sometimes, calling a function with certain arguments results in the error message formal argument \"foo\" matched by multiple actual arguments. Is it possible to pr

Answer 1

library(mixtools)
wait = faithful$waiting
mixmdl = normalmixEM(wait)

plot(mixmdl, which = 2, xlim = c(25, 110), ylim = c(0, .5), nclass=20)
#Error in hist.default(x, prob = TRUE, main = main2, xlab = xlab2, ylim = c(0,  : 
#  formal argument "ylim" matched by multiple actual arguments

The error message is quite informative. It tells you which function gets passed the parameter twice. For more information:

traceback()

# 4: hist.default(x, prob = TRUE, main = main2, xlab = xlab2, ylim = c(0, 
#                                                                      maxy), ...)
# 3: hist(x, prob = TRUE, main = main2, xlab = xlab2, ylim = c(0, 
#                                                              maxy), ...)
# 2: plot.mixEM(mixmdl, which = 2, xlim = c(25, 110), ylim = c(0, 
#                                                              0.5), nclass = 20)
# 1: plot(mixmdl, which = 2, xlim = c(25, 110), ylim = c(0, 0.5), 
#         nclass = 20)

So, there is a call to hist in plot.mixEM that already sets ylim = c(0,maxy). Your ylim = c(0,0.5) gets passed via the ellipsis (...), so that hist.default gets passed ylim twice. Hence, the error.