Avoiding the infamous “eval(parse())” construct

Question

Ok, so I\'m running some loops to process data stored in list objects. Ever mindful of the infamous fortune admonishment not to use eval(parse(mystring))

Answer 1

Using get and [[:

bar <- list(foo = list(fast = 1:5, slow = 6:10),
            oof = list(6:10, 1:5))

rab <- 'bar'

get(rab)[['oof']]
# [[1]]
# [1]  6  7  8  9 10
# 
# [[2]]
# [1] 1 2 3 4 5

Answer 2

If the name of your top list is going to change and be accessed by a variable with the name then it is best to put those lists into another list, then you can access the list you want using [[. Also read fortune(312) and the help on ?'[['.

You can then access the pieces in a different ways (detailed on the help page ?'[[').

mylist <- list()
mylist$bar <- bar

mylist[[rab]][['oof']]
#or
mylist[[ c(rab,'oof') ]]