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2011 Jul 28
1
Calculating difference in variable values (e.g. elapsed time) in data frame
...ta: time <- c("19:36:11","19:36:12","19:36:13","19:36:14","19:36:15","19:36:16") strptime(time, "%H:%M:%S") y<-c(197,194,189,179,166,150) mydata<-data.frame(time=time,y=y) OK, now how do I create a new variable, say, time_el, that would calculate the elapsed time since 19:36:11? I assume that I need the strptime() function to make sure R treats the character strings as time. Thank you very much for any & all assistance! -Philippe