Sorkin, John
2023-Jul-03 19:26 UTC
[R] Create matrix with column names wiht the same prefix xxxx and that end in 1, 2
Jeff,
Again my thanks for your guidance.
I replaced dimnames(myvalues)<-list(NULL,c(zzz))
with
colnames(myvalues)<-zzz
and get the same error,
Error in dimnames(x) <- dn :
length of 'dimnames' [2] not equal to array extent
It appears that I am creating the string zzz in a manner that is not compatable
with either
dimnames(myvalues)<-list(NULL,c(zzz))
or
colnames(myvalues)<-zzz
I think I need to modify the way I create the string zzz.
# create variable names xxx1 and xxx2.
string=""
for (j in 1:2){
name <- paste("xxx",j,sep="")
string <- paste(string,name)
print(string)
}
# Creation of xxx1 and xxx2 works
string
# Create matrix
myvalues <- matrix(nrow=2,ncol=4)
head(myvalues,1)
# Add "j" and "k" to the string of column names
zzz <- paste("j","k",string)
zzz
# assign column names, j, k, xxx1, xxx2 to the matrix
# create column names, j, k, xxx1, xxx2.
dimnames(myvalues)<-list(NULL,c(zzz))
colnames(myvalues)<-zzz
________________________________________
From: Jeff Newmiller <jdnewmil at dcn.davis.ca.us>
Sent: Monday, July 3, 2023 2:45 PM
To: Sorkin, John
Cc: r-help at r-project.org
Subject: Re: [R] Create matrix with column names wiht the same prefix xxxx and
that end in 1, 2
I really think you should read that help page. colnames() accesses the second
element of dimnames() directly.
On July 3, 2023 11:39:37 AM PDT, "Sorkin, John" <jsorkin at
som.umaryland.edu> wrote:>Jeff,
>Thank you for your reply.
>I should have said with dim names not column names. I want the Mateix to
have dim names, no row names, dim names j, k, xxx1, xxx2.
>
>John
>
>John David Sorkin M.D., Ph.D.
>Professor of Medicine
>Chief, Biostatistics and Informatics
>University of Maryland School of Medicine Division of Gerontology and
Geriatric Medicine
>Baltimore VA Medical Center
>10 North Greene Street<x-apple-data-detectors://12>
>GRECC<x-apple-data-detectors://12> (BT/18/GR)
>Baltimore, MD 21201-1524<x-apple-data-detectors://13/0>
>(Phone) 410-605-711<tel:410-605-7119>9
>(Fax) 410-605-7913<tel:410-605-7913> (Please call phone number above
prior to faxing)
>
>On Jul 3, 2023, at 2:11 PM, Jeff Newmiller <jdnewmil at
dcn.davis.ca.us> wrote:
>
>??colnames
>
>On July 3, 2023 11:00:32 AM PDT, "Sorkin, John" <jsorkin at
som.umaryland.edu> wrote:
>I am trying to create an array, myvalues, having 2 rows and 4 columns, where
the column names are j,k,xxx1,xxx2. The code below fails, with the following
error, "Error in dimnames(myvalues) <- list(NULL, zzz) :
>length of 'dimnames' [2] not equal to array extent"
>
>Please help me get the code to work.
>
>Thank you,
>John
>
># create variable names xxx1 and xxx2.
>string=""
>for (j in 1:2){
>name <- paste("xxx",j,sep="")
>string <- paste(string,name)
>print(string)
>}
># Creation of xxx1 and xxx2 works
>string
>
># Create matrix
>myvalues <- matrix(nrow=2,ncol=4)
>head(myvalues,1)
># Add "j" and "k" to the string of column names
>zzz <- paste("j","k",string)
>zzz
># assign column names, j, k, xxx1, xxx2 to the matrix
># create column names, j, k, xxx1, xxx2.
>dimnames(myvalues)<-list(NULL,zzz)
>
>
>______________________________________________
>R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
>https://stat.ethz.ch/mailman/listinfo/r-help
>PLEASE do read the posting guide http://www.r-project.org/posting-guide.html
>and provide commented, minimal, self-contained, reproducible code.
>
>--
>Sent from my phone. Please excuse my brevity.
>
>______________________________________________
>R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
>https://stat.ethz.ch/mailman/listinfo/r-help
>PLEASE do read the posting guide http://www.r-project.org/posting-guide.html
>and provide commented, minimal, self-contained, reproducible code.
--
Sent from my phone. Please excuse my brevity.
Rui Barradas
2023-Jul-03 19:55 UTC
[R] Create matrix with column names wiht the same prefix xxxx and that end in 1, 2
?s 20:26 de 03/07/2023, Sorkin, John escreveu:> Jeff, > Again my thanks for your guidance. > I replaced dimnames(myvalues)<-list(NULL,c(zzz)) > with > colnames(myvalues)<-zzz > and get the same error, > Error in dimnames(x) <- dn : > length of 'dimnames' [2] not equal to array extent > It appears that I am creating the string zzz in a manner that is not compatable with either > dimnames(myvalues)<-list(NULL,c(zzz)) > or > colnames(myvalues)<-zzz > > I think I need to modify the way I create the string zzz. > > # create variable names xxx1 and xxx2. > string="" > for (j in 1:2){ > name <- paste("xxx",j,sep="") > string <- paste(string,name) > print(string) > } > # Creation of xxx1 and xxx2 works > string > > # Create matrix > myvalues <- matrix(nrow=2,ncol=4) > head(myvalues,1) > # Add "j" and "k" to the string of column names > zzz <- paste("j","k",string) > zzz > # assign column names, j, k, xxx1, xxx2 to the matrix > # create column names, j, k, xxx1, xxx2. > dimnames(myvalues)<-list(NULL,c(zzz)) > colnames(myvalues)<-zzz > ________________________________________ > From: Jeff Newmiller <jdnewmil at dcn.davis.ca.us> > Sent: Monday, July 3, 2023 2:45 PM > To: Sorkin, John > Cc: r-help at r-project.org > Subject: Re: [R] Create matrix with column names wiht the same prefix xxxx and that end in 1, 2 > > I really think you should read that help page. colnames() accesses the second element of dimnames() directly. > > On July 3, 2023 11:39:37 AM PDT, "Sorkin, John" <jsorkin at som.umaryland.edu> wrote: >> Jeff, >> Thank you for your reply. >> I should have said with dim names not column names. I want the Mateix to have dim names, no row names, dim names j, k, xxx1, xxx2. >> >> John >> >> John David Sorkin M.D., Ph.D. >> Professor of Medicine >> Chief, Biostatistics and Informatics >> University of Maryland School of Medicine Division of Gerontology and Geriatric Medicine >> Baltimore VA Medical Center >> 10 North Greene Street<x-apple-data-detectors://12> >> GRECC<x-apple-data-detectors://12> (BT/18/GR) >> Baltimore, MD 21201-1524<x-apple-data-detectors://13/0> >> (Phone) 410-605-711<tel:410-605-7119>9 >> (Fax) 410-605-7913<tel:410-605-7913> (Please call phone number above prior to faxing) >> >> On Jul 3, 2023, at 2:11 PM, Jeff Newmiller <jdnewmil at dcn.davis.ca.us> wrote: >> >> ??colnames >> >> On July 3, 2023 11:00:32 AM PDT, "Sorkin, John" <jsorkin at som.umaryland.edu> wrote: >> I am trying to create an array, myvalues, having 2 rows and 4 columns, where the column names are j,k,xxx1,xxx2. The code below fails, with the following error, "Error in dimnames(myvalues) <- list(NULL, zzz) : >> length of 'dimnames' [2] not equal to array extent" >> >> Please help me get the code to work. >> >> Thank you, >> John >> >> # create variable names xxx1 and xxx2. >> string="" >> for (j in 1:2){ >> name <- paste("xxx",j,sep="") >> string <- paste(string,name) >> print(string) >> } >> # Creation of xxx1 and xxx2 works >> string >> >> # Create matrix >> myvalues <- matrix(nrow=2,ncol=4) >> head(myvalues,1) >> # Add "j" and "k" to the string of column names >> zzz <- paste("j","k",string) >> zzz >> # assign column names, j, k, xxx1, xxx2 to the matrix >> # create column names, j, k, xxx1, xxx2. >> dimnames(myvalues)<-list(NULL,zzz) >> >> >> ______________________________________________ >> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see >> https://stat.ethz.ch/mailman/listinfo/r-help >> PLEASE do read the posting guide http://www.r-project.org/posting-guide.html >> and provide commented, minimal, self-contained, reproducible code. >> >> -- >> Sent from my phone. Please excuse my brevity. >> >> ______________________________________________ >> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see >> https://stat.ethz.ch/mailman/listinfo/r-help >> PLEASE do read the posting guide http://www.r-project.org/posting-guide.html >> and provide commented, minimal, self-contained, reproducible code. > > -- > Sent from my phone. Please excuse my brevity. > ______________________________________________ > R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code.Hello, I should have pointed out in my answer that you are inded creating the names vector in a (very) wrong way. When in the loop you paste string and name you create one vector of length 1. When the loop ends, you have " xxx1 xxx2", not two names. string="" for (j in 1:2){ name <- paste("xxx",j,sep="") string <- paste(string,name) print(string) } #> [1] " xxx1" #> [1] " xxx1 xxx2" # Creation of xxx1 and xxx2 works string #> [1] " xxx1 xxx2" Quoting the comment above, Creation of xxx1 and xxx2 works No, it does not! And then you paste again, adding two extra letters to one string zzz <- paste("j","k",string) This zzz also is of length 1, check it. With a loop the right way would be any of # 1. concatenate the current name with string string <- NULL # or c(), perhaps more frequent for (j in 1:2){ name <- paste("xxx",j,sep="") string <- c(string, name) print(string) } #> [1] "xxx1" #> [1] "xxx1" "xxx2" # Now creation of xxx1 and xxx2 does work string #> [1] "xxx1" "xxx2" # 2. create a vector of the appropriate length beforehand, my preferred string <- character(2) for (j in 1:2){ string[j] <- paste0("xxx",j,sep="") print(string) } #> [1] "xxx1" "" #> [1] "xxx1" "xxx2" # Creation of xxx1 and xxx2 works string #> [1] "xxx1" "xxx2" But the vectorized way is still the better one. Hope this helps, Rui Barradas