? subset day = x time > y | time < z --- On Thu, 5/12/11, hwright <heather.wri...@maine.edu> wrote:
> From: hwright <heather.wri...@maine.edu> > Subject: Re: [R] How to extract information from the following dataset? > To: r-help@r-project.org > Received: Thursday, May 12, 2011, 6:18 AM > > I have the following data set, in a csv file, looks like > the following: > > Jan 27, 2010 16:01:24,000 125 - - - > Jan 27, 2010 16:06:24,000 125 - - - > ...... > The first few columns are month, day, year, time with OS3 > accuracy. And the > last number is the measurement I need to extract. > I wonder if there is a easy way to just take out the > measurements only from > a specific day and hour > -- > Xin Zhang > Ph.D Candidate > Department of Statistics > University of California, Riverside > ------------------------------------------------------------------- > > I use strptime to configure the date format in my times > series dataset. > First check to see how the dates are read. > For example: > # check the structure > str(your_file) > 'data.frame' ...etc > This tells me that my original date is a factor but not in > POSIXlt format. > > #check your column dates > head(your_file) > [1] "1984-01-26" "1984-02-09" "1984-03-01" "1984-03-15" > "1984-03-29" > "1984-04-12" > These are discrete column dates. > > #convert your date format > your_file$date<- strptime(your_file$date,"%m/%d/%Y") > call ?strptime for options > > Example: > For a specific day or hour, strptime would utilize: > strptime(your_file$date,"%d/%I") for day and hour. > > Once you extract the type of date format you want, run > str(your_file) again > to confirm the format change. > Does this answer your question? > Best, > > > > ----- > ------------------------------- > Heather A. Wright, PhD candidate > Ecology and Evolution of Plankton > Stazione Zoologica Anton Dohrn > Villa Comunale > 80121 - Napoli, Italy > -- > View this message in context: > http://r.789695.n4.nabble.com/How-to-extract-information-from-the-following-dataset-tp3516752p3516952.html > Sent from the R help mailing list archive at Nabble.com. > > ______________________________________________ > R-help@r-project.org > mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, > reproducible code. > ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
