desiderata for data manipulation
rossini@blindglobe.net (A.J. Rossini) writes:
MM> Dear Tony, can you elaborate what you are missing here for R? In R, it would be a simple command to reshape a dataframe, from a single-observation per individual (or other unit having repeated measurements) to multiple lines (one per measurement). Quite often, in building models, I'll switch between wide/long versions of the data set to build useful variables for modeling.
Almost, but not quite stack()/unstack()... The basic cases of "reshape long" looks like it would be a piece of cake to model over the subset() and stack() functions. "reshape wide" looks a little more tricky, unless you want to brutally assume that you're dealing with the result of a previous "reshape long". (The problem would be that in principle you'd know what to do with A B Y 1 1 0.1 A Y1 Y2 1 2 0.3 ----> 1 0.1 0.3 2 1 0.7 2 0.7 0.9 2 2 0.9 but suppose there's a fifth line as in A B Y 1 1 0.1 1 2 0.3 2 1 0.7 2 2 0.9 2 2 1.1 Then you'd have two candidates for the value of Y2 for A==2 and it wouldn't help to assume that there are really two cases with A==2, because you can't really be sure about to which case the Y1 should belong.)
O__ ---- Peter Dalgaard Blegdamsvej 3 c/ /'_ --- Dept. of Biostatistics 2200 Cph. N (*) \(*) -- University of Copenhagen Denmark Ph: (+45) 35327918 ~~~~~~~~~~ - (p.dalgaard@biostat.ku.dk) FAX: (+45) 35327907 -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-devel mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html Send "info", "help", or "[un]subscribe" (in the "body", not the subject !) To: r-devel-request@stat.math.ethz.ch _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._