The usual way I filter is: KL$Dt <- as.Date( KL$date, format='%d-%m-%y' ) KL2 <- KL[ !is.na( KL$Dt ), ] -- Sent from my phone. Please excuse my brevity. On June 10, 2017 10:17:52 PM PDT, Jeff Newmiller <jdnewmil at dcn.davis.ca.us> wrote: >You are using a slash in your format string to separate sub-fields but >your data uses a dash.