Hy, I have this:

list(
myvector_a=c("X1","X2","X3"),
myvector_b=c("X1","X3","X4"),
myvector_c=c("X2","X5","X6"))->mydata

Expected output: build manually

list(
  myvector_a=list(c_1_1=myvector_a[[1]],
                  c_1_2=myvector_a[[2]],
                  c_1_3=myvector_a[[3]],
                  c_2_1=c(myvector_a[[1]],myvector_a[[2]]),
                  c_2_1=c(myvector_a[[1]],myvector_a[[3]]),
                  c_2_1=c(myvector_a[[2]],myvector_a[[3]]),
                  c_3_1=c(myvector_a[[1]],myvector_a[[2]],myvector_a[[3]])),
  myvector_b=list(c_1_1=myvector_b[[1]],
                  c_1_2=myvector_b[[2]],
                  c_1_3=myvector_b[[3]],
                  c_2_1=c(myvector_b[[1]],myvector_b[[2]]),
                  c_2_1=c(myvector_b[[1]],myvector_b[[3]]),
                  c_2_1=c(myvector_b[[2]],myvector_b[[3]]),
                  c_3_1=c(myvector_b[[1]],myvector_b[[2]],myvector_b[[3]])),
  myvector_c=list(c_1_1=myvector_c[[1]],
                  c_1_2=myvector_c[[2]],
                  c_2_1=c(myvector_c[[1]],myvector_c[[2]])))->result

This was my closest solution to what I need:

x<-NULL
for(i in 1:3)
  for(j in 1:length(mydata[[i]]))
    combn(mydata[[i]],j) -> result[[paste0(names(mydata[i]))]][[paste0("c_",i,"_",j)]]

For example, in Output obtained: result[["myvector_a"]][["c_1_2"]] I couldn't separate as in Expected output: result[["myvector_a"]][["c_2_1"]], result[["myvector_a "]][["c_2_2"]] and result[["myvector_a"]][["c_2_3"]].

Expected output:                                                                     Output obtained:

CodePudding user response：

Here's a way using lapply within lapply -

result <- lapply(mydata, function(x) {
  unlist(lapply(seq_along(x), function(y) combn(x, y, list)), recursive = FALSE)
})

Using list and unlist is done only to get the required structure of the output. If you are not too concerned about it this would work as well.

result <- lapply(mydata, function(x) lapply(seq_along(x), function(y) combn(x, y)))