# [R] Merge list to list - as matrix

Gabor Grothendieck ggrothendieck at gmail.com
Mon Aug 28 13:53:52 CEST 2006

```Here are two ways:

1. use indexes:

lapply(seq(along = x), function(i) cbind(x[[i]], y[[i]]))

2. use mapply:

mapply(cbind, x, y, SIMPLIFY = FALSE)

On 8/28/06, Muhammad Subianto <msubianto at gmail.com> wrote:
> Dear all,
>
> I have dataset
> x <- list(matrix(1:20, 5, 4),matrix(1:20, 5, 4),matrix(1:20, 5, 4))
> y <- list(matrix(110:114, 5, 1),matrix(110:114, 5, 1),matrix(110:114, 5, 1))
>
> I need merge x and y as list (y put in last column).
> The result is something like
>
> [[1]]
>     [,1] [,2] [,3] [,4]  [,5]
> [1,]    1    6   11   16   110
> [2,]    2    7   12   17   111
> [3,]    3    8   13   18   112
> [4,]    4    9   14   19   113
> [5,]    5   10   15   20   114
>
> [[2]]
>     [,1] [,2] [,3] [,4]  [,5]
> [1,]    1    6   11   16   110
> [2,]    2    7   12   17   111
> [3,]    3    8   13   18   112
> [4,]    4    9   14   19   113
> [5,]    5   10   15   20   114
>
> [[3]]
>     [,1] [,2] [,3] [,4]  [,5]
> [1,]    1    6   11   16   110
> [2,]    2    7   12   17   111
> [3,]    3    8   13   18   112
> [4,]    4    9   14   19   113
> [5,]    5   10   15   20   114
>
> I have tried
> a <- list(x,y)
> as.data.frame(t(sapply(a, rbind)))
> lapply(a, function(x) matrix(unlist(x), nrow = length(x), byrow = TRUE))
> but I don't know how to fix it.
>