> Re: [R] Counting Elements Conditionally > Jean V Adams > to: > Edward Patzelt > 08/22/2011 03:53 PM > > > [R] Counting Elements Conditionally > > Edward Patzelt > > to: > > r-help > > 08/22/2011 02:33 PM > > > > R - > > > > I have 3 variables with data below. Variable "Rev" is a vector that > changes > > from 1 to 2, 2 to 3, etc.... Variable "FF" is a binary variable with > 1's > > and 0's. Variable "bin" is a different binary variable with 1's and > 0's. > > > > I want to calculate the number of elements: > > > > 1. Starting with the first element where Rev switches (i.e. 1 to 2) > > > > 2. The number of elements between the transition and the first 0 in the > > "FF" vector; *when "bin" is also a 0.* > > * > > * > > 3. I want to do this for each transition in Rev, but ignore all > elements > > after calculating #2 until another transition has occurred. > > > > > > structure(list(Rev = c(1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, > > 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 2L, 2L, 2L, 2L, 2L, 2L, > > 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L), FF = c(0L, > > 1L, 1L, 1L, 1L, 0L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 0L, 1L, 1L, > > 1L, 1L, 0L, 1L, 0L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 0L, 0L, 1L, 1L, > > 1L, 1L, 1L, 0L, 1L, 1L, 1L), bin = c(NA, 1, 1, 1, 1, 1, 1, 1, > > 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 0, 1, > > 0, 0, 1, 0, 0, 0, 0, 0, 1, 1, 1)), .Names = c("Rev", "FF", "bin" > > ), row.names = c(NA, -40L), class = "data.frame") > > > > > > -- > > Edward H. Patzelt > > Research Assistant ? TRiCAM Lab > > University of Minnesota ? Psychology/Psychiatry > > VA Medical Center > > Office: S355 Elliot Hall - Twin Cities Campus > > Phone: 612-626-0072 Email: patze...@umn.edu > > > > Try this (I'm assuming your data.frame is called "df": > > > uR <- unique(df$Rev) > uR0 <- uR*10L > > first.Rev <- match(uR, df$Rev) > first.Rev0 <- match(uR0, df$Rev * 10L + df$FF) > > no.elements <- first.Rev0 - first.Rev + 1 > > > This starts with Rev=1 (rather than Rev=2), but you can get rid of that by > dropping the first result ... > > > no.elements[-1] > > > Jean >
Ooops. Too hasty in my reply. I missed the part about bin also being zero. Try this instead. uR <- unique(df$Rev) uR00 <- uR*100L first.Rev <- match(uR, df$Rev) first.Rev00 <- match(uR00, df$Rev * 100L + df$FF * 10L + df$bin) no.elements <- first.Rev00 - first.Rev + 1 Jean [[alternative HTML version deleted]] ______________________________________________ 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.