?tapply temp.data<-data[as.character(data$time %in% c("02:00","03:00","04:00"),] # one quick and dirty method is to create a subset the data , not sure what format your time data is so converted to character strings.
then something like: tapply(temp.data$V1, factor(temp.data$time), mean) Wayne -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of jerzack Sent: 13 September 2007 10:26 To: [EMAIL PROTECTED] Subject: [R] pick time intervalls Hello, as an R beginner I have a question concerning the following data set: nr date time V1 V2 V3 V4 V5 V6 ... 2828 26/08/05 20:00 60 38 55 58 53 56 2829 26/08/05 21:00 58 34 54 49 45 53 2830 26/08/05 22:00 56 35 52 51 46 47 2831 26/08/05 23:00 56 35 50 45 46 38 2832 27/08/05 00:00 61 34 49 42 47 32 2833 27/08/05 01:00 62 38 52 49 48 36 2834 27/08/05 02:00 64 39 51 49 50 42 2835 27/08/05 03:00 63 40 49 46 49 33 2836 27/08/05 04:00 58 37 47 48 51 20 ... How can I access values at a certain time intervall every day. For example I would like to calculate the mean of the V1 values for the times 02:00 - 04:00 every day. Thank you very much for your help! jeremy -- View this message in context: http://www.nabble.com/pick-time-intervalls-tf4434604.html#a12651552 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.