[R] documenting quirky behavior of as.POSIXct, as.POSIX.lt regarding AM/PM, possibly other cases

[Galkowski, Jan]

I wanted to put this on the R Wiki, but found the suitable pages were read-only.  I wanted to get it out in public to save people work.

I was converting dates like "2009/03/26 01:00:00 AM" using as.POSIXct.  I found that using a format of "%Y/%m/%d %I:%M:%S %p" did not work correctly to distinguish AM from PM.  Both were converted into the same timestamp.  Indeed, what I found worked was affixing a space after the string timestamp to produce "2009/03/26 01:00:00 AM " or "2009/03/26 01:00:00 PM ".  That works.

Didn't see this documented in the associated pages anywhere. 

I wonder if the help system might benefit from user comments like for instance PHP has?