HI, May be this helps: dat1 <- read.table(text=" 20100914 08:01, 3.74 20100914 08:11, 3.74 20100914 08:21, 3.71 20100914 08:31, 4.39 20100914 08:41, 3.74 20100915 08:01, 3.64 20100915 08:11, 3.54 20100915 08:21, 3.61 20100915 08:31, 4.49 20100915 08:41, 3.84 ", sep=",",header=FALSE,stringsAsFactors=FALSE) tapply(dat1$V2,list(as.Date(dat1$V1,format="%Y%m%d %H:%M")),function(x) x) #$`2010-09-14` #[1] 3.74 3.74 3.71 4.39 3.74 # #$`2010-09-15` #[1] 3.64 3.54 3.61 4.49 3.84 A.K.
----- Original Message ----- From: Matthijs Daelman <matthijs.dael...@gmail.com> To: r-help@r-project.org Cc: Sent: Saturday, December 22, 2012 5:58 AM Subject: [R] Does R have an equivalent for Matlab's cell array? Hi I have a time series of measurements: every 10 min. a value was logged. The data look like: 20100914 08:01 3.74 20100914 08:11 3.74 20100914 08:21 3.71 20100914 08:31 4.39 20100914 08:41 3.74 This data spans several months. I would like to group the data per day. In Matlab it is fairly easy to obtain a cell array, of which the first column contains the date of each day, and the second column contains a vector, that in its turn contains all values for the corresponding day. That looks like 14-9-2010 [3.74 3.74 3.71 4.39 3.74...] 15-9-2010 [...] and so on. Is it possible to create a similar data structure in in R? I was thinking of a data frame, similar to the Matlab's cell array, but it doesn't look like data frames can contain vectors. Something like a two dimensional list would do the trick, I believe, but does that exist? Thanks Kind regards Matthijs Daelman ______________________________________________ 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.