Dear List,
I have a data frame of data taken every few seconds. I would like to subset
the data to retain only the data taken on the quarter hour, and as close to the
quarter hour as possible. So far I have figured out how to subset the data to
the quarter hour, but not how to keep only the minimum time for each quarter
hour.
For example:
mytime<-c("12:00:00","12:00:05","12:15:05","12:15:06","12:20:00","12:30:01","12:45:01","13:00:00","13:15:02")
subtime<-grep(pattern="[[:digit:]]+[[:punct:]]00[[:punct:]][[:digit:]]+|[[:digit:]]+[[:punct:]]15[[:punct:]][[:digit:]]+|[[:digit:]]+[[:punct:]]30[[:punct:]][[:digit:]]+|[[:digit:]]+[[:punct:]]45[[:punct:]][[:digit:]]+",mytime)
mytime[subtime]
[1] "12:00:00" "12:00:05" "12:15:05" "12:15:06" "12:30:01" "12:45:01"
"13:00:00" "13:15:02"
This gives me the data taken at quarter hour intervals (removes 12:20:00) but I
am still left with multiple values at the quarter hours.
I would like to obtain:
"12:00:00" "12:15:05" "12:30:01" "12:45:01" "13:00:00" "13:15:02"
Thanks!
Tim
Tim Clark
Department of Zoology
University of Hawaii
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