[R] Calculating difference in variable values (e.g. elapsed time) in data frame
Philippe.Hensel at noaa.gov
Thu Jul 28 17:38:42 CEST 2011
I have a data frame containing time (e.g. GMT), and I would like to
create/add a new variable that would be the computation of the elapsed
time since the first observation. Does anyone have a suggestion for an
easy way to do this? I am having trouble creating a new variable that
would contain just the first time observation (then I could take
difference between actual time and initial time).
e.g. - here's a brief representation of the data:
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!
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