A Calculation on list object

Hello, I am into some calculation on a list object, therefore requesting the peers if there is any short cut way to so the same calculation.

Let say I have following list object:
List <- vector('list', length = 3)
set.seed(1)
List[[1]] <- rnorm(5)
List[[2]] <- rnorm(2)
List[[3]] <- rnorm(7)
List
[[1]]
[1] -0.6264538  0.1836433 -0.8356286  1.5952808  0.3295078

[[2]]
[1] -0.8204684  0.4874291

[[3]]
[1]  0.7383247  0.5757814 -0.3053884  1.5117812  0.3898432 -0.6212406 -2.2146999
Vector <- 3:5
Vector
[1] 3 4 5

Now, what I want to do is, add List with Vector, element-by-element. Means I wanted to do:
List[[1]] + Vector[1]
[1] 2.373546 3.183643 2.164371 4.595281 3.329508
List[[2]] + Vector[2]
[1] 3.179532 4.487429
List[[3]] + Vector[3]
[1] 5.738325 5.575781 4.694612 6.511781 5.389843 4.378759 2.785300

Till now I have done this calculation with for-loop. Therefore it would be interesting if there is any elegant way to do the same.

Thanks,
Hi Ron,

Seems like there might be a really elegant way, but I would use
lapply().  For instance:

lapply(seq_along(List), function(x) List[[x]] + Vector[x])

If you do this regularly and want something that reads more
intuitively, consider defining an operator that does this.  %+% is
undefined (at least on my system), so something like:

set.seed(1)
List <- list(rnorm(5), rnorm(2), rnorm(7))
Vector <- 3:5

"%+%" <- function(e1, e2) {
  if (identical(length(e1), length(e2)))
    lapply(seq_along(e1), function(i) e1[[i]] + e2[[i]])
  else stop("length of e1 (", length(e1),
    ") must match length of e2 (", length(e2), ").")
}

List %+% Vector
List %+% 11:13

This has the advantage of looking more like how you are thinking (add
elements of the list to elements of the vector).

Hope this helps,

Josh
Hello, I am into some calculation on a list object, therefore requesting the peers if there is any short cut way to so the same calculation.

Let say I have following list object:

List <- vector('list', length = 3)
set.seed(1)
List[[1]] <- rnorm(5)
List[[2]] <- rnorm(2)
List[[3]] <- rnorm(7)
List
[[1]]
[1] -0.6264538 ?0.1836433 -0.8356286 ?1.5952808 ?0.3295078

[[2]]
[1] -0.8204684 ?0.4874291

[[3]]
[1] ?0.7383247 ?0.5757814 -0.3053884 ?1.5117812 ?0.3898432 -0.6212406 -2.2146999

Vector <- 3:5
Vector
[1] 3 4 5

Now, what I want to do is, add List with Vector, element-by-element. Means I wanted to do:

List[[1]] + Vector[1]
[1] 2.373546 3.183643 2.164371 4.595281 3.329508
List[[2]] + Vector[2]
[1] 3.179532 4.487429
List[[3]] + Vector[3]
[1] 5.738325 5.575781 4.694612 6.511781 5.389843 4.378759 2.785300

Till now I have done this calculation with for-loop. Therefore it would be interesting if there is any elegant way to do the same.

Thanks,

______________________________________________
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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/
Hello, I am into some calculation on a list object, therefore requesting the peers if there is any short cut way to so the same calculation.

Let say I have following list object:

List <- vector('list', length = 3)
set.seed(1)
List[[1]] <- rnorm(5)
List[[2]] <- rnorm(2)
List[[3]] <- rnorm(7)
List
[[1]]
[1] -0.6264538 ?0.1836433 -0.8356286 ?1.5952808 ?0.3295078

[[2]]
[1] -0.8204684 ?0.4874291

[[3]]
[1] ?0.7383247 ?0.5757814 -0.3053884 ?1.5117812 ?0.3898432 -0.6212406 -2.2146999

Vector <- 3:5
Vector
[1] 3 4 5

Now, what I want to do is, add List with Vector, element-by-element. Means I wanted to do:

List[[1]] + Vector[1]
[1] 2.373546 3.183643 2.164371 4.595281 3.329508
List[[2]] + Vector[2]
[1] 3.179532 4.487429
List[[3]] + Vector[3]
[1] 5.738325 5.575781 4.694612 6.511781 5.389843 4.378759 2.785300

Till now I have done this calculation with for-loop. Therefore it would be interesting if there is any elegant way to do the same.

Try this:

mapply("+", List, Vector)
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