See the Other Applications section of the R News 4/1 help desk article on dates.
On 7/18/07, Mr Natural <[EMAIL PROTECTED]> wrote: > > Proper calendar dates in R are great for plotting and calculating. > However for the non-wonks among us, they can be very frustrating. > I have recently discussed the pains that people in my lab have had > with dates in R. Especially the frustration of bringing date data into R > from Excel, which we have to do a lot. > > Please find below a simple analgesic for R date importation that I > discovered > over the last 1.5 days (Learning new stuff in R is calculated in 1/2 days). > > The function dates() gives the simplest way to get calendar dates into > R from Excel that I can find. > But straight importation of Excel dates, via a csv or txt file, can be a a > huge pain (I'll give details for anyone who cares to know). > > My pain killer is: > Consider that you have Excel columns in month, day, year format. Note that R > hates date data that does not lead with the year. > > a. Load the chron library by typing library(chron) in the console. > You know that you need this library from information revealed by > performing the query, > ?dates()" in the Console window. This gives the R documentation > help file for this and related time, date functions. In the upper left > of the documentation, one sees "dates(chron)". This tells you that you > need the library chron. > > b. Change the format "dates" in Excel to format "general", which gives > 5 digit Julian dates. Import the csv file (I use read.csv() with the > Julian dates and other data of interest. > > c. Now, change the Julian dates that came in with the csv file into > calendar dates with the dates() function. Below is my code for performing > this activity, concerning an R data file called ss, > > ss holds the Julian dates, illustrated below from the column MPdate, > > >ss$MPdate[1:5] > [1] 34252 34425 34547 34759 34773 > > The dates() function makes calendar dates from Julian dates, > > >dmp<-dates(ss$MPdate,origin=c(month = 1, day = 1, year = 1900)) > > > dmp[1:5] > [1] 10/12/93 04/03/94 08/03/94 03/03/95 03/17/95 > > I would appreciate the comments of more sophisticated programmers who > can suggest streamlining or shortcutting this operation. > > regards, Don > > > > > -- > View this message in context: > http://www.nabble.com/dates%28%29-is-a-great-date-function-in-R-tf4105322.html#a11675205 > Sent from the R help mailing list archive at Nabble.com. > > ______________________________________________ > R-help@stat.math.ethz.ch 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@stat.math.ethz.ch 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.