Question

I would like to interweave two data.frame in R. For example:

a = data.frame(x=1:5, y=5:1)
b = data.frame(x=2:6, y=4:0)

I would like the result to look like:

> x y
  1 5
  2 4
  2 4
  3 3
  3 3
  ...  

obtained by cbinding x[1] with y[1], x[2] with y[2], etc.

What is the cleanest way to do this? Right now my solution involves spitting everthing out to a list and merging. This is pretty ugly:

lst = lapply(1:length(x), function(i) cbind(x[i,], y[i,]))
res = do.call(rbind, lst)

Answer 1

You can do this by giving x and y an index, rbind them and sort by the index.

a = data.frame(x=1:5, y=5:1)
b = data.frame(x=2:6, y=4:0)
df <- rbind(data.frame(a, index = 1:nrow(a)), data.frame(b, index = 1:nrow(b)))
df <- df[order(df$index), c("x", "y")]