# [R] Merge list to list - as list

Gabor Grothendieck ggrothendieck at gmail.com
Sun Sep 3 16:02:33 CEST 2006

```By the way here is another solution.  This one recursively descends
throught the list structure so that it that works regardless
of the nesting of your lists (provided x and y are compatible)
thus it can be used in answer to both the original post and
to this one:

cbind2 <- function(x, y) {
if (is.list(x))
mapply(cbind2, x, y, SIMPLIFY = FALSE)
else
cbind(x,y)
}

x <- list(list(matrix(1:20, 5, 4),matrix(1:20, 5, 4)),
list(matrix(1:20, 5, 4),matrix(1:20, 5, 4)))
y <- list(list(c(1, -1, -1, 1, 1),c(1, 1, -1, -1, -1)),
list(c(1, 1, 1, 1, 1),c(1, 1, -1, 1, -1)))
cbind2(x,y)
cbind2(x[], y[])
cbind2(x[][], y[][])

On 9/3/06, Gabor Grothendieck <ggrothendieck at gmail.com> wrote:
> If z is the result then z[[i]] is formed from x[[i]] and y[[i]] using
> the previous solution, viz.
>
> z <- list()
> z[] <- mapply(cbind, x[], y[], SIMPLIFY = FALSE)
> z[] <- mapply(cbind, x[], y[], SIMPLIFY = FALSE)
>
> or with a for loop (which is similar to the code you posted below except
> the extraneous j loop is removed since its already incorporated
> in the mapply):
>
> z <- list()
> for(i in seq(along = x))
>   z[[i]] <- mapply(cbind, x[], y[], SIMPLIFY = FALSE)
>
> or reducing the loop to a lapply:
>
> lapply(seq(along = x), function(i) mapply(cbind, x[[i]], y[[i]],
> SIMPLIFY = FALSE))
>
>
>
> On 9/3/06, Muhammad Subianto <msubianto at gmail.com> wrote:
> > Dear all,
> > #Last week, I asked about merge x and y as list.
> > #Now I have a dataset with list of list like:
> > x <- list(list(matrix(1:20, 5, 4),matrix(1:20, 5, 4)),
> >          list(matrix(1:20, 5, 4),matrix(1:20, 5, 4)))
> > y <- list(list(c(1, -1, -1, 1, 1),c(1, 1, -1, -1, -1)),
> >          list(c(1, 1, 1, 1, 1),c(1, 1, -1, 1, -1)))
> > x
> > y
> >
> > #I need merge x and y, I have tried with
> > list.uni <- vector("list", length(x))
> > for (i in 1:length(x)) {
> >     for (j in 1:length(x[])) {
> >          list.uni[[i]][[j]] <- mapply(cbind,
> >                                       x[[i]][[j]],
> >                                       y[[i]][[j]],
> >                                       SIMPLIFY=FALSE)
> >     }
> > }
> > list.uni
> >
> > I have learn about ?lapply, ?sapply and ?mapply but I still didn't
> > understand how to use it.
> > I need the result something like
> >
> >
> > []
> > [][]
> >     [,1] [,2] [,3] [,4] 
> > [1,]    1    6   11   16  1
> > [2,]    2    7   12   17  -1
> > [3,]    3    8   13   18  -1
> > [4,]    4    9   14   19  1
> > [5,]    5   10   15   20  1
> >
> > [][]
> >     [,1] [,2] [,3] [,4] 
> > [1,]    1    6   11   16  1
> > [2,]    2    7   12   17  1
> > [3,]    3    8   13   18  -1
> > [4,]    4    9   14   19  -1
> > [5,]    5   10   15   20  -1
> >
> >
> > []
> > [][]
> >     [,1] [,2] [,3] [,4] 
> > [1,]    1    6   11   16  1
> > [2,]    2    7   12   17  1
> > [3,]    3    8   13   18  1
> > [4,]    4    9   14   19  1
> > [5,]    5   10   15   20  1
> >
> > [][]
> >     [,1] [,2] [,3] [,4] 
> > [1,]    1    6   11   16  1
> > [2,]    2    7   12   17  1
> > [3,]    3    8   13   18  -1
> > [4,]    4    9   14   19  1
> > [5,]    5   10   15   20  -1
> >
> > Thanks you for any help.
> > Best wishes, Muhammad Subianto
> >
> >
> >
> >
> > #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] [,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
> > >
> > > []
> > >     [,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
> > >
> > > []
> > >     [,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.
> > >
> > > Regards, Muhammad Subianto
> >
> > ______________________________________________
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