Julia, I had a similar query a while ago which I solved using a suggestion from Gabor, have a look at:
http://finzi.psych.upenn.edu/R/Rhelp02a/archive/69597.html Hope it helps, Augusto -------------------------------------------- Augusto Sanabria. MSc, PhD. Mathematical Modeller Risk & Impact Analysis Group Geospatial & Earth Monitoring Division Geoscience Australia (www.ga.gov.au) Cnr. Jerrabomberra Av. & Hindmarsh Dr. Symonston ACT 2601 Ph. (02) 6249-9155 -----Original Message----- From: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org] On Behalf Of liujb Sent: Tuesday, 13 January 2009 8:58 To: r-help@r-project.org Subject: [R] roll weekly data to monthly level Dear R users: I have a data set that looks something like this: ID time y 1 2/01/2008 4 1 2/09/2008 12 1 9/01/2008 8 2 1/06/2008 3 2 3/01/2008 4 2 3/09/2008 9 2 6/03/2008 4 3 1/02/2008 3 3 1/10/2008 8 3 2/02/2008 7 3 2/10/2008 3 I'd like to sum up the weekly data to the monthly level, so that it looks something like this: ID time y 1 2/2008 16 1 9/2008 8 2 1/2008 3 2 3/2008 13 2 6/2008 4 3 1/2008 11 3 2/2008 10 What is the best way to do it? Time must be character. How do I truncate a character so that I can remove the date and only keep the month and year? Thank you very much in advance. Julia -- View this message in context: http://www.nabble.com/roll-weekly-data-to-monthly-level-tp21424700p21424700.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.
