On 09/07/2021 3:37 p.m., Laurent Rhelp wrote:
Very effective solution, I hope I remember that for the nex time.
The key things to remember are that in R a "list" object is a vector
whose elements are R objects, and that matrices are just vectors with
dimension attributes.
Those two ideas are each useful for other things, too!
Duncan Murdoch
Thank you
Le 09/07/2021 à 19:50, David Winsemius a écrit :
On 7/9/21 10:40 AM, Laurent Rhelp wrote:
Dear R-Help-list,
I have a list init_l containing 16 dataframes and I want to create
a matrix 4 x 4 from this list with a dataframe in every cell of the
matrix. I succeeded to do that but my loop is very uggly (cf. below).
Could somebody help me to write nice R code to do this loop ?
Thank you very much
Laurent
##
## mock data, 16 dataframes in a list
##
init_l <- lapply( seq(1,16) , function(x) {
data.frame( V1 = rnorm(3),
V2 = rnorm(3),
V3 = rnorm(3)
)
})
##
## lists matrix creation with n = 4 columns and n = 4 rows
##
n <- 4
Just assign a dimension attribute and you will have your two
dimensional structure
dim(init_l) <- c(n,n)
init_l[ 2,2]
[[1]]
V1 V2 V3
1 -1.4103259 1.9214184 -0.1590919
2 0.1899490 0.3842191 2.4502078
3 -0.4282764 -0.9992190 1.5384344
is.matrix(init_l)
[1] TRUE
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