Às 16:54 de 01/07/2024, Sorkin, John escreveu:
#I am trying to write code that will create a matrix with a variable number of
columns where the #number of columns is 1+Grps
#I can do this:
NSims <- 4
Grps <- 5
DiffMeans <- matrix(nrow=NSims,ncol=1+Grps)
DiffMeans
#I have a problem when I try to name the columns of the matrix. I want the
first column to be NSims, #and the other columns to be something like Value1,
Value2, . . . Valuen where N=Grps
# I wrote a function to build a list of length Grps
createValuelist <- function(num_elements) {
for (i in 1:num_elements) {
cat("Item", i, "\n", sep = "")
}
}
createValuelist(Grps)
# When I try to assign column names I receive an error:
#Error in dimnames(DiffMeans) <- list(NULL, c("NSim", createValuelist(Grps))) :
# length of 'dimnames' [2] not equal to array extent
dimnames(DiffMeans) <- list(NULL,c("NSim",createValuelist(Grps)))
DiffMeans
# Thank you for your help!
John David Sorkin M.D., Ph.D.
Professor of Medicine, University of Maryland School of Medicine;
Associate Director for Biostatistics and Informatics, Baltimore VA Medical
Center Geriatrics Research, Education, and Clinical Center;
PI Biostatistics and Informatics Core, University of Maryland School of
Medicine Claude D. Pepper Older Americans Independence Center;
Senior Statistician University of Maryland Center for Vascular Research;
Division of Gerontology and Paliative Care,
10 North Greene Street
GRECC (BT/18/GR)
Baltimore, MD 21201-1524
Cell phone 443-418-5382
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Hello,
Sorry for my first answer, I thought you only wanted to name the matrix
columns. After reading the OP again, this time actually reading it, I
realized you also want to create the matrix. This is even in the
question title line :(.
create_matrix <- function(nsims, ngrps, First = "NSims", Prefix = "Value") {
# could also be paste0(Prefix, seq_len(ngrps))
grp_names <- sprintf("%s%d", Prefix, seq_len(ngrps))
nms <- c(First, grp_names)
matrix(nrow = nsims, ncol = 1L + ngrps, dimnames = list(NULL, nms))
}
NSims <- 4
Grps <- 5
create_matrix(NSims, Grps)
#> NSims Value1 Value2 Value3 Value4 Value5
#> [1,] NA NA NA NA NA NA
#> [2,] NA NA NA NA NA NA
#> [3,] NA NA NA NA NA NA
#> [4,] NA NA NA NA NA NA
Hope this helps,
Rui Barradas
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