Re: [R] rownames, colnames, and date and time

From: Brandt, T. (Tobias) <TobiasBr_at_taquanta.com>
Date: Mon 03 Jul 2006 - 18:28:58 EST


Hi all

I was wondering whether there has ever been an update on the rownames and colnames behaviour as described by Eric below?

I still get the same behaviour, exactly as described by Eric, on my WinXP installation of R-2.3.0. I also posted a message to r-help on Friday but looking through the online archives it seems to have not made it to the list. I would agree with Eric that a consistent use of the typecast would be a reasonable solution.

Any comments?

Tobias Brandt
Quantitative Analyst
Taquanta Asset Managers
Nedbank Clock Tower
Victoria & Alfred Waterfront, Cape Town 8001 Tel : +27 (0) 21 416 6602
Fax : +27 (0) 21 416 9945
Email : TobiasBr@Taquanta.com <mailto:TobiasBr@Taquanta.com>

>-----Original Message-----
>From: r-help-bounces@stat.math.ethz.ch
>[mailto:r-help-bounces@stat.math.ethz.ch] On Behalf Of Erich Neuwirth
>Sent: 21 March 2006 01:31 PM
>To: R-help@stat.math.ethz.ch
>Cc: Christian Prinoth
>Subject: [R] rownames, colnames, and date and time
>
>I noticed something surprising (in R 2.2.1 on WinXP) According
>to the documentation, rownames and colnames are character vectors.
>Assigning a vector of class POSIXct or POSIXlt as rownames or
>colnames therefore is not strictly according to the rules.
>In some cases, R performs a reasonable typecast, but in some
>other cases where the same typecast also would be possible, it
>does not.
>
>Assigning a vector of class POSIXct to the rownames or names
>of a dataframe creates a reasonable string representation of
>the dates (and possibly times).
>Assigning such a vector to the rownames or colnames of a
>matrix produces rownames or colnames consisting of the integer
>representation of the date-time value.
>Trying to assign a vector of class POSIXlt in all cases
>(dataframes and matrices, rownames, colnames, names) produces an error.
>
>Demonstration code is given below.
>
>This is somewhat inconsistent.
>Perhaps a reasonable solution could be that the typecast used
>for POSIXct and dataframes is used in all the other cases also.
>
>Code:
>
>mymat<-matrix(1:4,nrow=2,ncol=2)
>mydf<-data.frame(mymat)
>mydates<-as.POSIXct(c("2001-1-24","2005-12-25"))
>
>rownames(mydf)<-mydates
>names(mydf)<-mydates
>rownames(mymat)<-mydates
>colnames(mymat)<-mydates
>
>print(deparse(mydates))
>print(deparse(rownames(mydf)))
>print(deparse(names(mydf)))
>print(deparse(rownames(mymat)))
>print(deparse(colnames(mymat)))
>
>mydates1<-as.POSIXlt(mydates)
>
># the following lines will not work and
># produce errors
>
>rownames(mydf)<-mydates1
>names(mydf)<-mydates1
>rownames(mymat)<-mydates1
>colnames(mymat)<-mydates1
>
>
>--
>Erich Neuwirth
>Institute for Scientific Computing and
>Didactic Center for Computer Science
>University of Vienna
>phone: +43-1-4277-39464 fax: +43-1-4277-39459
>
>______________________________________________
>R-help@stat.math.ethz.ch mailing list
>https://stat.ethz.ch/mailman/listinfo/r-help
>PLEASE do read the posting guide!
>http://www.R-project.org/posting-guide.html
>



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