[R] 'Date' elements within a matrix

[Gabor Grothendieck]

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"


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