[R] Remove empty list from list - remove only one row and make as matrix

[Muhammad Subianto]

Dear all,
Dimitris, thanks for your great help and quick response.

Best, Muhammad Subianto


 > dff[sapply(dff, is.matrix)]
[[1]]
      [,1] [,2] [,3] [,4] [,5]
[1,]    1    6   11   16    1
[2,]    4    9   14   19    1
[3,]    5   10   15   20    1

[[2]]
      [,1] [,2] [,3] [,4] [,5]
[1,]    3    8   13   18   -1
[2,]    5   10   15   20   -1

 > lapply(dff, function(x) if(!is.matrix(x)) rbind(x) else x)
[[1]]
      [,1] [,2] [,3] [,4] [,5]
[1,]    1    6   11   16    1
[2,]    4    9   14   19    1
[3,]    5   10   15   20    1

[[2]]
   [,1] [,2] [,3] [,4] [,5]
x    1    6   11   16    1

[[3]]
      [,1] [,2] [,3] [,4] [,5]
[1,]    3    8   13   18   -1
[2,]    5   10   15   20   -1

 >

On this day 29/08/2006 13:34, Dimitris Rizopoulos wrote:
> try the following:
> 
> # a
> dff[sapply(dff, is.matrix)]
> 
> # b
> lapply(dff, function(x) if(!is.matrix(x)) rbind(x) else x)
> 
> 
> I hope it helps.
> 
> Best,
> Dimitris
> 
> ----
> Dimitris Rizopoulos
> Ph.D. Student
> Biostatistical Centre
> School of Public Health
> Catholic University of Leuven
> 
> Address: Kapucijnenvoer 35, Leuven, Belgium
> Tel: +32/(0)16/336899
> Fax: +32/(0)16/337015
> Web: http://med.kuleuven.be/biostat/
>      http://www.student.kuleuven.be/~m0390867/dimitris.htm
> 
> 
> ----- Original Message ----- 
> From: "Muhammad Subianto" <msubianto at gmail.com>
> To: <r-help at stat.math.ethz.ch>
> Sent: Tuesday, August 29, 2006 1:22 PM
> Subject: Re: [R] Remove empty list from list - remove only one row and 
> make as matrix
> 
> 
>> Dear all,
>> After I work around, I found in my list of data with only one row 
>> which
>> need to remove or make it as matrix.
>> Here I write again my other toy example:
>> x <- list(matrix(1:20, 5, 4),matrix(1:20, 5, 4),matrix(1:20, 5,
>> 4),matrix(1:20, 5, 4),matrix(1:20, 5, 4))
>> y <- list(c(1, -1, -1, 1, 1),c(1, -1, -1, -1, -1),c(1, 1, 1, 1, 
>> 1),c(1,
>> 1, -1, 1, -1),c(-1, -1, -1, -1, -1))
>> ## Thanks to Gabor Grothendieck for this trick.
>> ## SIMPLIFY? SIMPLIFY >< simplify
>> xy.list <- mapply(cbind, x, y, SIMPLIFY=FALSE)
>>
>> point.class <-
>> t(cbind(c(10,20,15,4,-1),c(21,10,15,34,-1),c(11,13,6,3,1),c(7,5,5,2,1),c(8,9,5,12,-1)))
>> class.diffsame <- points.neighb(as.matrix(point.class), xy.list, 5)
>> pd.class <- points.diff(class.diffsame,xy.list)
>>
>> nc.test <- vector("list",length(pd.class))
>> for (i in 1:length(pd.class)) {
>>      nc.test[[i]] <- pd.class[[i]]$point.diff
>> }
>> nc.test
>>
>> # delete null/empty entries in a list
>> dff <- delete.NULLs(nc.test)
>> dff; str(dff)
>>> dff
>> [[1]]
>>      [,1] [,2] [,3] [,4] [,5]
>> [1,]    1    6   11   16    1
>> [2,]    4    9   14   19    1
>> [3,]    5   10   15   20    1
>>
>> [[2]]
>> [1]  1  6 11 16  1
>>
>> [[3]]
>>      [,1] [,2] [,3] [,4] [,5]
>> [1,]    3    8   13   18   -1
>> [2,]    5   10   15   20   -1
>>
>> lapply(dff, nrow)
>>> lapply(dff, nrow)
>> [[1]]
>> [1] 3
>>
>> [[2]]
>> NULL
>>
>> [[3]]
>> [1] 2
>>
>> #I can use
>> #dff[unlist(lapply(dff, nrow) == 1)] #2,3, etc
>>
>> I have two questions here:
>> a. I need to remove dff[[2]]
>> b. How to make it as matrix (in list). I mean the result something 
>> like
>>
>> [[1]]
>>      [,1] [,2] [,3] [,4] [,5]
>> [1,]    1    6   11   16    1
>> [2,]    4    9   14   19    1
>> [3,]    5   10   15   20    1
>>
>> [[2]]
>>      [,1] [,2] [,3] [,4] [,5]
>> [1]    1    6    11   16    1
>>
>> [[3]]
>>      [,1] [,2] [,3] [,4] [,5]
>> [1,]    3    8   13   18   -1
>> [2,]    5   10   15   20   -1
>>
>>
>> Best, Muhammad Subianto
>>
>>
>> points.neighb <- function(p.class, list.nc, class.col) {
>>    ntuples <- nrow(p.class)
>>    instvec <- vector("list",length=ntuples)
>>    for (i in 1:ntuples) {
>>         # Thanks to Petr Pikal for this trick
>>         instvec[[i]]$class.diff <- (p.class[i,class.col] -
>> list.nc[[i]][,class.col])!=0
>>         instvec[[i]]$class.same <- (p.class[i,class.col] -
>> list.nc[[i]][,class.col])==0
>>    }
>>    instvec
>> }
>>
>> points.diff <- function(p.class, list.nc) {
>>    ntuples <- length(list.nc)
>>    instvec <- vector("list",ntuples)
>>    for (i in 1:ntuples) {
>>         instvec[[i]]$point.diff <- 
>> list.nc[[i]][p.class[[i]]$class.diff,]
>>         instvec[[i]]$point.same <- 
>> list.nc[[i]][p.class[[i]]$class.same,]
>>    }
>>    instvec
>> }
>>
>> # Thanks to Jim Holtman for this trick
>> delete.NULLs  <-  function(x.list){
>>     x.list[unlist(lapply(x.list, length) != 0)]
>> }
>>