Accessing a vector element by name in R when some names are duplicated

Question

I had the vector x<-1:5 I named its elements (wrongly) names(x)<-rep(c(letters[1:4], "a")). How can I access the last element by name? x["a"] only return the first element named "a".

Answer 1

How about:

x[names(x) == "a"]
# a a 
# 1 5 

Or to get only the final one:

x[tail(which(names(x) == "a"), 1L)]
# a 
# 5

This is more readable but marginally slower than getting at what tail does directly (see getAnywhere("tail.default")):

x[(idx <- which(names(x) == "a"))[length(idx)]
# a 
# 5