[R] retaining formatting when converting a vector to a matrix/data.frame?
jim holtman
jholtman at gmail.com
Fri Jan 4 03:54:27 CET 2008
Here is a function that I use since the numeric value is the number of
seconds from 1/1/1970, which is the Unix time base that I am also
using:
unix2POSIXct <- function (time) structure(time, class = c("POSIXt", "POSIXct"))
It just reassigns the proper class.
On Jan 3, 2008 12:01 PM, Thomas Pujol <thomas.pujol at yahoo.com> wrote:
> Please see example code below.
>
> I have a vector ("mydata") of length 10. "mydata" can have various formats (e.g. numeric, text, POSIXct, etc) I use the matrix and data.frame functions to convert "mydata" to a dataframe ("mydf") of 2 columns and 5 rows.
>
> What is a "good" way to ensure that the format is retained when I create the data.frame?
> Currently, data in the "POSIXct" format is converted to numeric.
>
> Also, for my edification, is there a "good" way to convert numeric values such as these back to the original "POSIXct" format/values?
>
> Much thanks!
>
> #here I lose the "POSIXct" formatting
>
> mydata <- rep(Sys.time(), 10)
> str(mydata)
> mydf <- data.frame(matrix(data=mydata, nrow=5, ncol=2))
> str(mydf)
>
> #here using only "matrix" I also lose the "POSIXct" formatting
>
> mydata <- rep(Sys.time(), 10)
> str(mydata)
> mydf <- matrix(data=mydata, nrow=5, ncol=2)
> str(mydf)
>
>
> #this works as intended
> mydata <- rep(1:10)
> str(mydata)
> mydf <- data.frame(matrix(data=mydata, nrow=5, ncol=2))
> str(mydf)
>
>
>
> ---------------------------------
>
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>
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--
Jim Holtman
Cincinnati, OH
+1 513 646 9390
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