Just for the record, if you have NA's in it, you do : tapply(d,cut(d,round(length(d)/5)),mean, na.rm=T)
tapply applies a function over a vector by groups defined by another vector. In this case, it applies the function mean with the argument na.rm=T over the vector d by the groups defined by the cut function. cut splits a numeric vector in bins of equal size. In this case the vector is d and the amount of bins is round(length(d)/5). Cheers Joris On Sun, Jun 20, 2010 at 1:24 AM, Joris Meys <jorism...@gmail.com> wrote: > On Sat, Jun 19, 2010 at 4:29 AM, David Jarvis <thanga...@gmail.com> wrote: >> Hi, Joris. >> >> Thanks again; I don't get it. Reading the help pages for R reminds me of >> reading the manual pages for Unix: great for people who already know what it >> means. > > Just read them, from top to bottom, and take a look at the examples. > If you scare away from them, forget about ever finding your way around > R. Never skip the details, and just run the examples at the bottom. > Then you can see what's going on, it often clarifies things a whole > lot. > >> >> I can see how cut is dividing the data into 14 rows, and I can take the >> factor results from cut: >> >> tapply(d,cut(d,round(length(d)/5)),mean) >> >> But the results are ... well, negative? > > That is explained in the help file. The left side is not included in > the interval - (0,1] is equivalent to ]0,1]. To include the extreme > values, the lower limit is extended with 0.1% of the range. > >> >>> tapply(d,cut(d,round(length(d)/5)),mean) >> (-0.009,0.685] (0.685,1.38] (1.38,2.07] (2.07,2.77] (2.77,3.46] >> 0 1 2 NA 3 >> (3.46,4.15] (4.15,4.85] (4.85,5.54] (5.54,6.23] (6.23,6.93] >> 4 NA 5 6 NA >> (6.93,7.62] (7.62,8.32] (8.32,9.01] >> 7 8 9 >> >> I don't see how rounding up with ceiling would apply. > > well : 67/5 = 13,4. Round gives 13 bins, ceiling gives 14 bins. It's a > matter of choice. > >> >> I appreciate your patience; I think this might be beyond my capacity to >> understand. > > You ain't stupid. Lazy maybe, but definitely not stupid ;) > > Cheers > Joris > > > -- > Joris Meys > Statistical consultant > > Ghent University > Faculty of Bioscience Engineering > Department of Applied mathematics, biometrics and process control > > tel : +32 9 264 59 87 > joris.m...@ugent.be > ------------------------------- > Disclaimer : http://helpdesk.ugent.be/e-maildisclaimer.php > -- Joris Meys Statistical consultant Ghent University Faculty of Bioscience Engineering Department of Applied mathematics, biometrics and process control tel : +32 9 264 59 87 joris.m...@ugent.be ------------------------------- Disclaimer : http://helpdesk.ugent.be/e-maildisclaimer.php ______________________________________________ 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.
