[R] data frame manipulation with condition

[William Dunlap]

Use mult[as.character(df$x)] instead of mult[df$x].
They are different when df$x is a factor and the
character version is what you want.

  > df<- data.frame(x = c("AA","BB","CC","AA","DD","DD"), y = 1:6)
  > mult <- c(AA = 10, BB = 25,DD=15)
  > df$y <- df$y * mult[as.character(df$x)]
  > df
     x  y
  1 AA 10
  2 BB 50
  3 CC NA
  4 AA 40
  5 DD 75
  6 DD 90

This gets the order right.  The NA for "CC" is because
your vector of multipliers didn't include an entry for
CC.  You can either add CC=1 to mult or work only on the
subset of the data which has entries in the mult vector.

  > df<- data.frame(x = c("AA","BB","CC","AA","DD","DD"), y = 1:6)
  > mult <- c(AA = 10, BB = 25,DD=15)
  > i <- as.character(df$x) %in% names(mult)
  > df$y[i] <- df$y[i] * mult[as.character(df$x[i])]
  > df
     x  y
  1 AA 10
  2 BB 50
  3 CC  3
  4 AA 40
  5 DD 75
  6 DD 90

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 Arnaud Gaboury
> Sent: Friday, February 24, 2012 8:37 AM
> To: Uwe Ligges
> Cc: r-help at r-project.org
> Subject: Re: [R] data frame manipulation with condition
> 
> > df<- data.frame(x = c("AA","BB","CC","AA","DD","DD"), y = 1:6)
> > mult <- c(AA = 10, BB = 25,DD=15)
> > df$y <- df$y * mult[df$x]
> > df
>    x  y
> 1 AA 10
> 2 BB 50
> 3 CC 45
> 4 AA 40
> 5 DD NA
> 6 DD NA
> 
> My df is in fact much more longer than the chosen example shown here. It seems your tip didn't do the
> job.
> I am expecting this as result :
> 
> > df
>    x  y
> 1 AA 10  ----> if df$x==AA, df$y<-1*10
> 2 BB 50   ----> if df$x==BB, df$y<-2*25
> 3 CC 3         NOTHING
> 4 AA 40    ----> if df$x==AA, df$y<-4*10
> 5 DD 75   ----> if df$x==DD, df$y<-5*15
> 6 DD 90   ----> if df$x==DD, df$y<-6*15
> 
> Arnaud Gaboury
> 
> A2CT2 Ltd.
> 
> -----Original Message-----
> From: Uwe Ligges [mailto:ligges at statistik.tu-dortmund.de]
> Sent: vendredi 24 février 2012 17:07
> To: Arnaud Gaboury
> Cc: r-help at r-project.org
> Subject: Re: [R] data frame manipulation with condition
> 
> 
> 
> On 24.02.2012 16:59, Arnaud Gaboury wrote:
> > TY Uwe,
> >
> > So I will have to write a line for each condition? Right?
> >
> > In fact I was trying to do something with apply in one line, but couldn't achieve any result. In
> fact, all my transformation will be multiplying one object by a specific number according to the value
> of df$x.
> 
> In that case:
> 
> mult <- c(AA = 10, BB = 25)
> 
> Then:
> 
> 
> df$y <- df$y * mult[df$x]
> 
> 
> Uwe Ligges
> 
> 
> >
> > Arnaud Gaboury
> >
> > A2CT2 Ltd.
> >
> >
> > -----Original Message-----
> > From: Uwe Ligges [mailto:ligges at statistik.tu-dortmund.de]
> > Sent: vendredi 24 février 2012 16:33
> > To: Arnaud Gaboury
> > Cc: r-help at r-project.org
> > Subject: Re: [R] data frame manipulation with condition
> >
> >
> >
> > On 24.02.2012 16:25, Arnaud Gaboury wrote:
> >> Dear list,
> >>
> >> n00b question, but still can't find any easy answer.
> >>
> >> Here is a df:
> >
> >
> > Change
> >
> >>> df<-data.frame(cbind(x=c("AA","BB","CC","AA"),y=1:4))
> >
> > to
> >
> >    df<- data.frame(x = c("AA","BB","CC","AA"), y = 1:4)
> >
> > to make your object a sensible data.frame.
> >
> >
> >
> >>> df
> >>      x y
> >> 1 AA 1
> >> 2 BB 2
> >> 3 CC 3
> >> 4 AA 4
> >>
> >>
> >> I want to modify this df this way :
> >>    if df$x=="AA" then df$y=df$y*10
> >
> > df$y[df$x=="AA"]<- df$y[df$x=="AA"] * 25
> >
> > ...
> >
> >
> > Uwe Ligges
> >
> >
> >>    if df$x=="BB" then df$y=df$y*25
> >
> >
> >
> >
> >> and so on with other conditions.
> >>
> >> TY for any help.
> >>
> >> Trading
> >>
> >> A2CT2 Ltd.
> >>
> >>
> >> Arnaud Gaboury
> >>
> >> A2CT2 Ltd.
> >>
> >> ______________________________________________
> >> 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.