> I would like to change the > subset clause to be iter %% 500 _or_ the record is the last per n
If your data.frame df is sorted by n you can define the function isLastInRun <- function(x) c(x[-1] != x[-length(x)], TRUE) and use it as subset(df, iter %% 500 == 0 | isLastInRun(n)) Bill Dunlap Spotfire, TIBCO Software wdunlap tibco.com > -----Original Message----- > From: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org] On > Behalf > Of Giovanni Azua > Sent: Sunday, September 09, 2012 8:14 AM > To: r-help@r-project.org > Subject: [R] use subset to trim data but include last per category > > Hello, > > I bumped into the following funny use-case. I have too much data for a given > plot. I have > the following data frame df: > > > str(df) > 'data.frame': 5015 obs. of 5 variables: > $ n : Factor w/ 5 levels "1000","2000",..: 1 1 1 1 1 1 1 1 1 1 ... > $ iter : int 10 20 30 40 50 60 70 80 90 100 ... > $ Error : num 1.05e-02 1.24e-03 3.67e-04 1.08e-04 4.05e-05 ... > $ Duality_Gap: num 20080 3789 855 443 321 ... > $ Runtime : num 0.00536 0.01353 0.01462 0.01571 0.01681 ... > > But if I plot e.g. Runtime vs log(Duality Gap) I have too many observations > due to taking a > snapshot every 10 iterations rather than say 500 and the plot looks very > cluttered. So I > would like to trim the data frame including only those records for which iter > is multiple of > 500 and so I do this: > > df <- subset(df, iter %% 500 == 0) > > This gives me almost exactly what I need except that the last and most > important Duality > Gap observations are of course gone due to the filtering ... I would like to > change the > subset clause to be iter %% 500 _or_ the record is the last per n (n is my > problem size and > category in this case) ... how can I do that? > > I thought of adding a new column that flags whether a given row is the last > element per > category as "last" Boolean but this is a bit too complicated .. is there a > simpler condition > construct that can be used with the subset command? > > TIA, > Best regards, > Giovanni > ______________________________________________ > 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.
