Question

I often deal with objects of this form:

v <- list(one = c(a = 1, b = 2, c = 3), two = c(a = 10, b = 20, d = 30, c = 40))

and I would like to outer join these vectors by element name, to obtain:

  index value.x value.y
1     a       1      10
2     b       2      20
3     c       3      40
4     d      NA      30

I have written code to do this. In a nutshell, converts the vectors to data frames and reduces via successive merges. But I wonder if I have been reinventing the wheel and there is some function contained in a package, or in R base, possibly optimized. It seems a very common task.

Answer 1

Not sure this will be any simpler than your approach, but you could use reshape2 , lapply and as.list. I think the melt `dcast

library(reshape2)
dcast(melt(lapply(v, as.list)), L2 ~L1)
##   L2 one two
## 1  a   1  10
## 2  b   2  20
## 3  c   3  40
## 4  d  NA  30