We can do this using chron and zoo. First turn it into
a zoo series, z, using chron times, tt, which may not only
be useful for this but also for other purposes.
The ave(...) command gets a vector as long as the series with
the minimum dates in year each and then we aggregate z
by that using max.
I presume you want this separately for each of V3, V4 and V5,
and illustrated V4?
Let's first create a new column for the year. If the table is 'tab':
tab$year <- substring(tab$V1, 7)
Then by() almost does the job, but we need to reformat the result.
myfun <- function(tab, col) {
i <- whi
dear r-helpers
i've got a table that in extracts looks like this:
V1 V2 V3V4 V5
1 01/01/1975 00:00:00 125.837 3.691 296.618
2 01/01/1975 01:00:00 124.799 3.679 281.307
3 01/01/1975 02:00:00 111.607 3.536 281.307
4 02/24/1976 11:00:00 21.602 2.555 93.893
5 02/
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