[R] Set a zero at minimum row by group
William Dunlap
wdunlap at tibco.com
Tue Dec 18 23:34:07 CET 2012
I used the more complicated version because I didn't know if
df$x could contain values other than 0 and 1.
Bill Dunlap
Spotfire, TIBCO Software
wdunlap tibco.com
> -----Original Message-----
> From: David L Carlson [mailto:dcarlson at tamu.edu]
> Sent: Tuesday, December 18, 2012 2:30 PM
> To: William Dunlap; 'Carlos Nasher'; r-help at r-project.org
> Subject: RE: [R] Set a zero at minimum row by group
>
> This is a bit simpler:
>
> > df$x_new <- ave(df$T, df$ID, FUN=function(x)x!=min(x))
> > df
> ID T x x_new
> 1 1 1 0 0
> 2 1 2 1 1
> 3 1 3 1 1
> 4 2 1 0 0
> 5 2 4 1 1
> 6 3 3 0 0
> 7 3 5 1 1
> 8 3 6 1 1
> 9 3 8 1 1
>
> Are you sure there are no ties for the minimum value?
>
> ----------------------------------------------
> David L Carlson
> Associate Professor of Anthropology
> Texas A&M University
> College Station, TX 77843-4352
>
> > -----Original Message-----
> > From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
> > project.org] On Behalf Of William Dunlap
> > Sent: Tuesday, December 18, 2012 10:45 AM
> > To: Carlos Nasher; r-help at r-project.org
> > Subject: Re: [R] Set a zero at minimum row by group
> >
> > You should show what you tried with aggregate and tapply.
> >
> > You could use ave():
> > > wm <- as.logical(ave(df$T, df$ID, FUN=function(x)x==min(x)))
> > > df$x_new <- df$x
> > > df$x_new[wm] <- 0
> > > df
> > ID T x x_new
> > 1 1 1 1 0
> > 2 1 2 1 1
> > 3 1 3 1 1
> > 4 2 1 1 0
> > 5 2 4 1 1
> > 6 3 3 1 0
> > 7 3 5 1 1
> > 8 3 6 1 1
> > 9 3 8 1 1
> >
> > (The as.logical is there because ave() coerces the logical output of
> > FUN to the type of df$T, numeric, and we need to convert it back to
> > logical.)
> >
> > Bill Dunlap
> > Spotfire, TIBCO Software
> > wdunlap tibco.com
> >
> >
> > > -----Original Message-----
> > > From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
> > project.org] On Behalf
> > > Of Carlos Nasher
> > > Sent: Tuesday, December 18, 2012 6:10 AM
> > > To: r-help at r-project.org
> > > Subject: [R] Set a zero at minimum row by group
> > >
> > > Dear R Helpers,
> > >
> > > I'm struggling with a data preparation problem. I feel that it is a
> > quite
> > > easy task but I don't get it done. I hope you can help me with that.
> > >
> > > I have a data frame looking like this:
> > >
> > > ID <- c(1,1,1,2,2,3,3,3,3)
> > > T <- c(1,2,3,1,4,3,5,6,8)
> > > x <- rep(1,9)
> > > df <- data.frame(ID,T,x)
> > >
> > > >df
> > > ID T x
> > > 1 1 1
> > > 1 2 1
> > > 1 3 1
> > > 2 1 1
> > > 2 4 1
> > > 3 3 1
> > > 3 5 1
> > > 3 6 1
> > > 3 8 1
> > >
> > > I want to manipulate the x column in a way that for each customer
> > (ID) at
> > > the minimum of T the x value is set to zero. The result should look
> > like
> > > this:
> > >
> > > ID T x x_new
> > > 1 1 1 0
> > > 1 2 1 1
> > > 1 3 1 1
> > > 2 1 1 0
> > > 2 4 1 1
> > > 3 3 1 0
> > > 3 5 1 1
> > > 3 6 1 1
> > > 3 8 1 1
> > >
> > > I already tried the aggregate() and apply() function, but I don't get
> > the
> > > result I'm looking for. I would glad if you could help me out.
> > >
> > > Best regards,
> > > Carlos
> > >
> > > [[alternative HTML version deleted]]
> > >
> > > ______________________________________________
> > > R-help at 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 at 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.
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