# [R] Count number of consecutive zeros by group

PIKAL Petr petr.pikal at precheza.cz
Fri Nov 1 17:24:36 CET 2013

```Hi

Yes you are right. This gives number of zeroes not max number of consecutive zeroes.

Regards
Petr

> -----Original Message-----
> From: arun [mailto:smartpink111 at yahoo.com]
> Sent: Friday, November 01, 2013 2:17 PM
> To: R help
> Cc: PIKAL Petr; Carlos Nasher
> Subject: Re: [R] Count number of consecutive zeros by group
>
> I think this gives a different result than the one OP asked for:
>
> df1 <- structure(list(ID = c(1L, 1L, 1L, 1L, 1L, 1L, 1L, 2L, 2L, 2L,
> 2L, 2L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L), x = c(1, 0, 0, 1, 0,
> 0, 0, 1, 2, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0)), .Names = c("ID",
> "x"), row.names = c(NA, -22L), class = "data.frame")
>
> with(df1, sapply(split(x, ID), function(x) sum(x==0)))
>
> with(df1,tapply(x,list(ID),function(y) {rl <- rle(!y);
> max(c(0,rl\$lengths[rl\$values]))}))
>
>
> A.K.
>
>
> On Friday, November 1, 2013 6:01 AM, PIKAL Petr
> <petr.pikal at precheza.cz> wrote:
> Hi
>
> Another option is sapply/split/sum construction
>
> with(data, sapply(split(x, ID), function(x) sum(x==0)))
>
> Regards
> Petr
>
>
> > -----Original Message-----
> > From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
> > project.org] On Behalf Of Carlos Nasher
> > Sent: Thursday, October 31, 2013 6:46 PM
> > To: S Ellison
> > Cc: r-help at r-project.org
> > Subject: Re: [R] Count number of consecutive zeros by group
> >
> > If I apply your function to my test data:
> >
> > ID <- c(1,1,1,2,2,3,3,3,3)
> > x <- c(1,0,0,0,0,1,1,0,1)
> > data <- data.frame(ID=ID,x=x)
> > rm(ID,x)
> >
> > f2 <-   function(x) {
> >   max( rle(x == 0)\$lengths )
> > }
> > with(data, tapply(x, ID, f2))
> >
> > the result is
> > 1 2 3
> > 2 2 2
> >
> > which is not what I'm aiming for. It should be
> > 1 2 3
> > 2 2 1
> >
> > I think f2 does not return the max of consecutive zeros, but the max
> > of any consecutve number... Any idea how to fix this?
> >
> >
> > 2013/10/31 S Ellison <S.Ellison at lgcgroup.com>
> >
> > >
> > >
> > > > -----Original Message-----
> > > > So I want to get the max number of consecutive zeros of variable
> x
> > > > for
> > > each
> > > > ID. I found rle() to be helpful for this task; so I did:
> > > >
> > > > FUN <- function(x) {
> > > >   rles <- rle(x == 0)
> > > > }
> > > > consec <- lapply(split(df[,2],df[,1]), FUN)
> > >
> > > You're probably better off with tapply and a function that returns
> > > what you want. You're probably also better off with a data frame
> > > name that isn't a function name, so I'll use dfr instead of df...
> > >
> > > dfr<- data.frame(x=rpois(500, 1.5), ID=gl(5,100)) #5 ID groups
> > > numbered 1-5, equal size but that doesn't matter for tapply
> > >
> > > f2 <-   function(x) {
> > >         max( rle(x == 0)\$lengths )
> > > }
> > > with(dfr, tapply(x, ID, f2))
> > >
> > >
> > > S Ellison
> > >
> > >
> > > *******************************************************************
> > > This email and any attachments are confidential. Any
> > > u...{{dropped:24}}
> >
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