On Dec 22, 2012, at 2:58 AM, Matthijs Daelman wrote: > 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.
That's a surprising conclusion. Vectors are typical components of dataframes. > Something like a two dimensional list would do the trick, I believe, but does > that exist? A dataframe _is_ a two-dimensional list. You should probably explain what you are trying to do, since there is very possibly a better way of structuring this problem without recasting the data into a "wide format". Most of the data processing in R is handled very well without such a strategy. If you wanted to proceed despite my misgivings, then there are several functions such as `split`, `tapply` and `by` that could allow you to segregate such data. It's best to use dput to present the data since console output is often ambiguous as to the underlying data structures. >From what you have offered it's not clear that you have yet done the data >input processing. -- David Winsemius Alameda, CA, USA ______________________________________________ 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.
