Hi, I have 2 questions on list object:
1. Suppose I have a matrix like:
dat <- matrix(1:9,3)
Now I want to replicate this entire matrix 3 times and put entire result in a
list object. Means, if "res" is the resulting list then I should have:
res[[1]]=dat, res[[2]]=dat, res[[3]]=dat
How can I do that in the easilest manner?
2. Suppose I have 2 list objects:
list1 <- list2 <- vector("list", length=2)
for(i in 1:2) {
list1[[i]] <- matrix(rnorm(15), 3)
list2[[i]] <- matrix(rnorm(15), 3)
}
How can I add these 2 list objects? I have tried with just list1+list2, however
it is generating some error.
Would be grateful for any help.
Thanks,
[[alternative HTML version deleted]]
On Sat, Jan 8, 2011 at 6:26 AM, Ron Michael <ron_michael70 at yahoo.com> wrote:> Hi, I have 2 questions on list object: > > 1. Suppose I have a matrix like: > dat <- matrix(1:9,3) > > Now I want to replicate this entire matrix 3 times and put entire result in a list object. Means, if "res" is the resulting list then I should have: > > res[[1]]=dat, res[[2]]=dat, res[[3]]=dat > > How can I do that in the easilest manner? > > 2. Suppose I have 2 list objects: > list1 <- list2 <- vector("list", length=2) > for(i in 1:2) { > ??list1[[i]] <- matrix(rnorm(15), 3) > ??list2[[i]] <- matrix(rnorm(15), 3) > ?} > > How can I add these 2 list objects? I have tried with just list1+list2, however it is generating some error. >Try these: rep(list(dat), 3) Map(`+`, list1, list2) -- Statistics & Software Consulting GKX Group, GKX Associates Inc. tel: 1-877-GKX-GROUP email: ggrothendieck at gmail.com
On Sat, 8 Jan 2011, Ron Michael wrote:> Hi, I have 2 questions on list object: > ? > 1. Suppose I have a matrix like: > dat <- matrix(1:9,3) > ? > Now I want to replicate this entire matrix 3 times and put entire result in a list object. Means, if "res" is the resulting list then I should have: > ? > res[[1]]=dat, res[[2]]=dat, res[[3]]=dat > ? > How can I do that in the easilest manner?See ?rep ... Examples ... ## replicate a list ...> ? > 2. Suppose I have 2 list objects: > list1 <- list2 <- vector("list", length=2) > for(i in 1:2) { > ??list1[[i]] <- matrix(rnorm(15), 3) > ??list2[[i]] <- matrix(rnorm(15), 3) > ?} > > How can I add these 2 list objects? I have tried with just list1+list2, however it is generating some error. > ?See ?mapply take note of the SIMPLIFY arg, which you want as FALSE HTH, Chuck> Would be grateful for any help. > ? > Thanks, > > > [[alternative HTML version deleted]] > >Charles C. Berry Dept of Family/Preventive Medicine cberry at tajo.ucsd.edu UC San Diego http://famprevmed.ucsd.edu/faculty/cberry/ La Jolla, San Diego 92093-0901
Hi Ron,
Here you go.
Cheers,
Josh
dat <- matrix(1:9,3)
ldat <- list(dat, dat, dat)
ldat[[1]] == dat
## Or
lapply(1:3, function(x) dat)
## which is similar in spirit to
output <- vector("list", 3)
for(i in 1:3) {
output[[i]] <- dat
}
list1 <- list2 <- vector("list", length=2)
for(i in 1:2) {
list1[[i]] <- matrix(rnorm(15), 3)
list2[[i]] <- matrix(rnorm(15), 3)
}
lapply(1:2, function(x) {list1[[x]] + list2[[x]]})
## This can be done more simply
lapply(1:2, function(x) {matrix(rnorm(15), 3) + matrix(rnorm(15), 3)})
On Sat, Jan 8, 2011 at 3:26 AM, Ron Michael <ron_michael70 at yahoo.com>
wrote:> Hi, I have 2 questions on list object:
>
> 1. Suppose I have a matrix like:
> dat <- matrix(1:9,3)
>
> Now I want to replicate this entire matrix 3 times and put entire result in
a list object. Means, if "res" is the resulting list then I should
have:
>
> res[[1]]=dat, res[[2]]=dat, res[[3]]=dat
>
> How can I do that in the easilest manner?
>
> 2. Suppose I have 2 list objects:
> list1 <- list2 <- vector("list", length=2)
> for(i in 1:2) {
> ??list1[[i]] <- matrix(rnorm(15), 3)
> ??list2[[i]] <- matrix(rnorm(15), 3)
> ?}
>
> How can I add these 2 list objects? I have tried with just list1+list2,
however it is generating some error.
>
> Would be grateful for any help.
>
> Thanks,
>
>
> ? ? ? ?[[alternative HTML version deleted]]
>
>
> ______________________________________________
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> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>
>
--
Joshua Wiley
Ph.D. Student, Health Psychology
University of California, Los Angeles
http://www.joshuawiley.com/