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

From: Dimitris Rizopoulos <dimitris.rizopoulos_at_med.kuleuven.be>
Date: Tue 29 Aug 2006 - 21:34:13 EST

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


> 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)]
> }
>
> ______________________________________________
> R-help@stat.math.ethz.ch mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>

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