days <- seq(as.Date("1970/1/1"), as.Date("2003/12/31"), "days")
temp <- rnorm(length(days), mean=10, sd=8)
tapply(temp, format(days,"%Y-%m"), mean)
tapply(temp, format(days,"%b"), mean)> -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of Majid Iravani > Sent: Thursday, February 01, 2007 8:11 AM > To: [email protected] > Subject: [R] How can I calculate conditional mean in a large > dataset including date data > > Dear R users, > > I have a dataframe with two columns: first column is date data (e.g. > 1/1/2000 with character format: daily data from 1/1/1970 till > 31/12/2003) > and second column is temperature value. Now I'd like to > calculate mean for > each month in a year (i.e. May 2001, June 1997) and mean for > each month in > all of years. As the number of days in some months is > different from others > I could not write appreciate command for this. Therefore I > would greatly > appreciate if somebody can help me in this case > > Thank you > Majid > -------------------------------------------------------------- > ------------------ > Majid Iravani > PhD Student > Swiss Federal Research Institute WSL > Research Group of Vegetation Ecology > Zürcherstrasse 111 CH-8903 Birmensdorf Switzerland > Phone: +41-1-739-2693 > Fax: +41-1-739-2215 > Email: [EMAIL PROTECTED] > http://www.wsl.ch/staff/majid.iravani/ > > ______________________________________________ > [email protected] 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. > ______________________________________________ [email protected] 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.
