Awesome, this is close, couple changes.  Below is full data set for 1
person.  I want the code to look at the first time it sees a 0 in FF after
the transition in Rev.  I then want it to test whether bin is also a 0.  If
and only if this is the first 0 in FF after the transition, and bin = 0,
then count the number of elements between the transition in Rev and the 0 in
FF.

structure(list(Rev = c(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, 3L,
3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 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, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L,
3L, 3L, 3L, 3L, 3L, 3L, 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, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L,
3L, 3L, 3L), FF = c(1L, 1L, 0L, 1L, 1L, 1L, 1L, 1L, 0L, 1L, 0L,
1L, 1L, 1L, 1L, 1L, 0L, 1L, 1L, 1L, 1L, 1L, 0L, 1L, 1L, 1L, 0L,
1L, 1L, 1L, 1L, 0L, 1L, 1L, 1L, 1L, 0L, 1L, 1L, 1L, 0L, 1L, 1L,
1L, 1L, 1L, 1L, 1L, 0L, 1L, 1L, 1L, 0L, 1L, 1L, 1L, 1L, 0L, 1L,
1L, 1L, 1L, 0L, 1L, 1L, 1L, 1L, 1L, 1L, 0L, 1L, 1L, 0L, 1L, 1L,
1L, 1L, 1L, 1L, 0L, 1L, 1L, 1L, 0L, 1L, 1L, 0L, 1L, 1L, 1L, 1L,
0L, 1L, 1L, 1L, 1L, 0L, 1L, 1L, 1L, 1L, 0L, 1L, 1L, 1L, 0L, 1L,
1L, 1L, 1L, 1L, 0L, 1L, 1L, 1L, 1L, 0L, 1L, 1L, 1L, 0L, 1L, 1L,
1L, 1L), bin = c(NA, 1, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 0,
1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1,
1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 1, 0, 1,
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 0, 0, 1, 1, 1, 1, 1, 1,
1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
0, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1, 1, 0, 0, 0, 1, 1, 1, 1, 1, 1,
1, 1, 1, 1, 1)), .Names = c("Rev", "FF", "bin"), row.names = c(NA,
-125L), class = "data.frame")


On Mon, Aug 22, 2011 at 3:57 PM, Jean V Adams <jvad...@usgs.gov> wrote:

>
> > 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




-- 
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

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