Combine two lists in a dataframe in R

Question

I have two lists with different structure:

listA <- list(c("a","b","c"), c("d","e"))
listB <- list(0.05, 0.5)

listA
[[1]]
[1] "a" "b" "c"

[[2]]
[1] "d" "e"

listB
[[1]]
[1] 0.05

[[2]]
[1] 0.5

I have an idea of how to use looping to combine both lists in a dataframe that looks like the one below but I'm sure that there is a more efficient way of doing this.

data.frame(A = c("a","b","c","d","e"), B = c(rep(0.05,3), rep(0.5,2)))
  A    B
1 a 0.05
2 b 0.05
3 c 0.05
4 d 0.50
5 e 0.50

Answer 1

This is another option:

do.call(rbind, Map(data.frame, A=listA, B=listB))

#   A    B
# 1 a 0.05
# 2 b 0.05
# 3 c 0.05
# 4 d 0.50
# 5 e 0.50

Answer 2

Maybe there is a more elegant way that keeps the class numeric of list2's elements... But this one works as well

df <- do.call(rbind,mapply(cbind, listA, listB))
df <- as.data.frame(df, stringsAsFactors = FALSE)
df[,2] <- as.numeric(df[,2])

EDIT Way better is Matthew Plourde's solution using Map aka mapply(data.frame, A=listA, B=listB, SIMPLIFY = FALSE)