On May 13, 2010, at 11:25 PM, emorway wrote:
Forum,
I've got hourly data for roughly 5 months of time that I want to
subset into
successive weeks. The first two elements of the dataset are
well.80.2$date[1]
[1] 6/12/2000 2:00
9256 Levels: 10/1/2001...
well.80.2$date[2]
[1] 6/12/2000 3:00
9256 Levels: 10/1/2001....
and so on until mid-october. I've been able to add 1 week the first
element
with the following:
as.POSIXlt(paste(as.character(as.Date(well.80.2$date[1],"%m/%d/%Y
%H:%M")+7),as.character(format(strptime(well.80.2$date[1],"%m/%d/%Y
%H:%M"),"%H:%M")),sep=" "))
[1] "2000-06-19 02:00:00"
What I've been unable to do is then use this for comparative
purposes in the
subset command, something to the effect of:
contin.80.2<-subset(well.80.2,well.80.2$date>=well.80.2$date[1]) &
You simply cannot do comparisons with factor data. You need to make a
variable that is of Date or DateTime or ti or zoo class. Then do you
comparisons.
well.80.2$date <
as.POSIXlt(paste(as.character(as.Date(well.80.2$date[1],"%m/%d/%Y
%H:%M")+7),as.character(format(strptime(well.80.2$date[1],"%m/%d/%Y
%H:%M"),"%H:%M")),sep=" "))
If there is an easier way to parse the dataset into weekly bins
taking into
consideration the hours, I'm open to suggestions.
Thank you.
--
--
David Winsemius, MD
West Hartford, CT
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