CODEWITHSUNDEEP
rloopsappend
Expectation mean first moment
Expectation mean first moment

Reputation: 366

Append to a list without needing a for loop in R

I would like to append to list without needing to specify the index from a for loop. For example

I would like to use the append() function (or similar) to get the same result as l. Unfortunately, append() combines all elements of tmp, tmp1 into a single vector.

tmp <- matrix(rnorm(9),3,3)

tmp1 <- matrix(rnorm(12),4,3)

l <- list(tmp,tmp1)
append(tmp,tmp1)

Thank you.

Upvotes: 0

Views: 567

Answers (3)

jay.sf
jay.sf

Reputation: 72593

For multiple lists try list with do.call.

tmp1 <- tmp2 <- matrix(rnorm(9),3,3)
tmp3 <- tmp4 <- matrix(rnorm(12),4,3)

do.call(list, mget(ls(pattern='^tmp')))
# $tmp1
# [,1]      [,2]        [,3]
# [1,] 0.3155314 0.5651536 -0.06577049
# [2,] 0.3141578 0.4890589  0.08431155
# [3,] 0.5168662 0.3297473  1.02775261
# 
# $tmp2
# [,1]      [,2]        [,3]
# [1,] 0.3155314 0.5651536 -0.06577049
# [2,] 0.3141578 0.4890589  0.08431155
# [3,] 0.5168662 0.3297473  1.02775261
# 
# $tmp3
# [,1]        [,2]      [,3]
# [1,]  0.53883661  1.19557871 0.2140172
# [2,] -1.53804925 -0.08647519 0.1795095
# [3,] -1.09212014  0.19291727 0.8241137
# [4,]  0.03080796  1.75626270 2.1196755
# 
# $tmp4
# [,1]        [,2]      [,3]
# [1,]  0.53883661  1.19557871 0.2140172
# [2,] -1.53804925 -0.08647519 0.1795095
# [3,] -1.09212014  0.19291727 0.8241137
# [4,]  0.03080796  1.75626270 2.1196755

Upvotes: 0

ThomasIsCoding
ThomasIsCoding

Reputation: 101044

Try append with list

> append(list(tmp), list(tmp1))
[[1]]
           [,1]       [,2]       [,3]
[1,] -1.6917740  2.2938118 -0.5994428
[2,] -0.8317474 -2.1021389  1.0077591
[3,] -0.6893888 -0.3864561  0.5299755

[[2]]
           [,1]       [,2]        [,3]
[1,]  0.6431510  1.6601869 -0.03001407
[2,] -0.8729105 -0.8919077  0.68717777
[3,]  0.4114760 -1.4556726 -1.52659021
[4,]  1.1093545  1.0937816  1.11888348

Upvotes: 0

tacoman
tacoman

Reputation: 947

You can use c() to append to preexisting list.

tmp <- matrix(rnorm(9),3,3)

tmp1 <- matrix(rnorm(12),4,3)

l <- list(tmp,tmp1)
l <- c(l, list(tmp))
l
[[1]]
           [,1]       [,2]       [,3]
[1,] -0.2516447 -0.7518535 -0.6249582
[2,]  0.5050876 -1.7664830  0.7357084
[3,] -1.2784381 -1.0874359  0.2894429

[[2]]
           [,1]        [,2]       [,3]
[1,]  0.1234092 -1.55219184  0.9395962
[2,] -1.1052530  1.24147499 -1.3515137
[3,] -2.1012372 -0.93570884  1.3275042
[4,] -0.1431186 -0.09361099  0.3836124

[[3]]
           [,1]       [,2]       [,3]
[1,] -0.2516447 -0.7518535 -0.6249582
[2,]  0.5050876 -1.7664830  0.7357084
[3,] -1.2784381 -1.0874359  0.2894429

Upvotes: 3

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