[R] Date Not Staying in Date Format

[Don MacQueen]

Try following this example:

>  foo <- Sys.time()
>  class(foo)
[1] "POSIXt"  "POSIXct"
>  ick <- as.numeric(foo)
>  ick
[1] 1138667199
>  class(ick)
[1] "numeric"
>  class(ick) <- class(foo)
>  ick
[1] "2006-01-30 16:26:39 PST"

-Don

At 3:51 PM -0500 1/30/06, David Randel wrote:
>I have a column in a data frame that has a class of "Date" and a mode of
>"numeric".  When I:
>
>max(df$Date)
>
>My output stays in Date format, i.e. "2006-01-03".
>
>However, when I run the following statment:
>
>tapply(df$Date, df$SomeFactor, max)
>
>my output looks like this:  9129   9493   9861  10226  10591  10956  11320 
>11687  12052  12417
>
>The returned object is of mode "numeric" and class "array".  Each array
>element is of mode "numeric" and class "numeric".  I believe that this is
>the integer representation of my date.  I can't seem to convert it back to a
>date.
>
>How do I get these to be intrepreted as a date instead of a number?
>
>Thanks,
>~Dave R.
>
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-- 
--------------------------------------
Don MacQueen
Environmental Protection Department
Lawrence Livermore National Laboratory
Livermore, CA, USA