Re: [R] 'Date' elements within a matrix

From: Bogaso Christofer <bogaso.christofer_at_gmail.com>
Date: Sun, 13 Mar 2011 21:16:38 +0530

Thanks everyone for clarifying my query. However I was wondering why that Date character is not preserved within a matrix? Why R forcefully changes that to numeric? I am especially concerned because as per the definition of the matrix, each element needs to be of same class. Is there any other example other than Date class which R forcefully changes to some simpler class if it placed within a matrix?

Thanks and regards,

-----Original Message-----
From: Gabor Grothendieck [mailto:ggrothendieck_at_gmail.com] Sent: 12 March 2011 02:46
To: Bogaso Christofer
Cc: r-help_at_r-project.org
Subject: Re: [R] 'Date' elements within a matrix

On Fri, Mar 11, 2011 at 4:15 PM, Bogaso Christofer <bogaso.christofer_at_gmail.com> wrote:
> Dear all, when I put date objects (class of 'Date') in a matrix it
> becomes
> numeric:
>
>> dat <- matrix(seq(as.Date("2011-01-01"), as.Date("2011-01-09"), by="1
> day"), 3)
>
>> dat
>
>      [,1]  [,2]  [,3]
>
> [1,] 14975 14978 14981
>
> [2,] 14976 14979 14982
>
> [3,] 14977 14980 14983
>
>> class(dat[1,1])
>
> [1] "numeric"
>
>
>
> As it could not preserve the 'Date' characteristics after putting my
> Date observations, I find it difficult to carry forward further
> calculation with Dates. Can somebody help me on how to preserve the
> Data properties while storing them within some matrix?

If its important to you to store them in a matrix (as opposed to a data frame) then try storing them in a matrix of lists:

> dd <- seq(as.Date("2011-01-01"), as.Date("2011-01-09"), by = "day") m
> <- matrix(as.list(dd), 3) m[[1,1]]
[1] "2011-01-01"

-- 
Statistics & Software Consulting
GKX Group, GKX Associates Inc.
tel: 1-877-GKX-GROUP
email: ggrothendieck at gmail.com

______________________________________________
R-help_at_r-project.org mailing list
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.
Received on Sun 13 Mar 2011 - 15:29:01 GMT

Archive maintained by Robert King, hosted by the discipline of statistics at the University of Newcastle, Australia.
Archive generated by hypermail 2.2.0, at Sun 13 Mar 2011 - 17:20:22 GMT.

Mailing list information is available at https://stat.ethz.ch/mailman/listinfo/r-help. Please read the posting guide before posting to the list.

list of date sections of archive