[R] Convert character date time to R date-time variable.

David Winsemius dw|n@em|u@ @end|ng |rom comc@@t@net
Fri Dec 8 22:30:07 CET 2023

On 12/7/23 08:21, Sorkin, John wrote:
> Colleagues,
> I have a matrix of character data that represents date and time. The format of each element of the matrix is
> "2020-09-17_00:00:00"
> How can I convert the elements into a valid R date-time constant?

You will not be able to store these datetime values in an R matrix, at 
least as class POSIXct. You could with class POSIXlt, but I've not seen 
it used before but it does appear possible since matrices can contain 

R matrices do no provide the capability to assign attributes, so only 
atomic types and lists can be elements. If you wanted to maintain the 
same structure, your first step might be to coerce to a data.frame and 
then proceed, or to first construct a vector and then use as the first 
argument to `matrix`.



> Thank you,
> John
> John David Sorkin M.D., Ph.D.
> Professor of Medicine, University of Maryland School of Medicine;
> Associate Director for Biostatistics and Informatics, Baltimore VA Medical Center Geriatrics Research, Education, and Clinical Center;
> PI Biostatistics and Informatics Core, University of Maryland School of Medicine Claude D. Pepper Older Americans Independence Center;
> Senior Statistician University of Maryland Center for Vascular Research;
> Division of Gerontology and Paliative Care,
> 10 North Greene Street
> GRECC (BT/18/GR)
> Baltimore, MD 21201-1524
> Cell phone 443-418-5382
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