r - find list item where all values match a regular expression -

question

given list of vectors

lst [[1]] [1] "{{=number}}"  [[2]] [1] ""  [[3]] [1] "auto"   "small"  "medium" "large"   [[4]] [1] "r1" "r2" "r3" "r4" "r5"  [[5]] [1] "1" "2" "3" "4" "5" 

how find entry consists of set of r[0-9] combinations?

so in exmample lst[[4]]

some rules

• the list item i'm after contain r[0-9] values.
• the number of r[0-9] values change in each list
• the next list item set of numbers, each being values used in r[0-9] element

data

dput(lst) list("{{=number}}", "", c("auto", "small", "medium", "large"),       c("r1", "r2", "r3", "r4", "r5"), c("1", "2", "3", "4", "5"      )) 

@jenesaisquoi has provided nice solution:

vapply(lst, function(x) all(grepl('^r[0-9]', x)), logical(1))  # [1] false false false  true false  ## e.g # lst[vapply(lst, function(x) all(grepl('^r[0-9]', x)), logical(1))] # [[1]] # [1] "r1" "r2" "r3" "r4" "r5"