Question on list objects

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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
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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)})
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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