Hi,
How about this?
set.seed(5)
dat<-data.frame(x=sample(1:20,6,replace=TRUE),a=sample(20:40,6,replace=TRUE))
dat1<-within(dat,{f=a/median(a);x_new=x*f})
dat1
# x a x_new f
#1 5 31 5.081967 1.0163934
#2 14 36 16.524590 1.1803279
#3 19 40 24.918033 1.3114754
#4 6 22 4.327869 0.7213115
#5 3 25 2.459016 0.8196721
#6 15 30 14.754098 0.9836066
#or
res<-do.call(data.frame,lapply(lapply(1,function(y) dat),function(y)
{y$f<-y$a/median(y$a);y$x_new<-y$f*y$x;y}))
A.K.
________________________________
From: meng <laomen...@163.com>
To: arun <smartpink...@yahoo.com>
Cc: R help <r-help@r-project.org>
Sent: Monday, December 24, 2012 5:29 AM
Subject: Re:Re: [R] How to do it through 1 step?
Yes,this is my final solution,but if I wanna add many new variables,and maybe
the following "new variables" are computed based on the previous " new
variables", this solution maybe difficult.
At 2012-12-24 17:01:03,arun <smartpink...@yahoo.com> wrote:
>HI,
>
>Not sure if this works for you.
>set.seed(5)
>dat<-data.frame(x=sample(1:20,6,replace=TRUE),a=sample(20:40,6,replace=TRUE))
> dat1<-transform(dat,f=a/median(a),x_new=x*(a/median(a)))
> head(dat1,2)
># x a f x_new
>#1 5 31 1.016393 5.081967
>#2 14 36 1.180328 16.524590
>A.K.
>
>
>
>
>----- Original Message -----
>From: meng <laomen...@163.com>
>To: r-help@r-project.org
>Cc:
>Sent: Monday, December 24, 2012 12:55 AM
>Subject: [R] How to do it through 1 step?
>
>A data set(dat),has 2 variables: x and a, and 100 rows.
>
>I wanna add 2 variables,and call the new data set dat1:
>var1:f = a/median(a)
>var2:x_new = x*f
>
>My solution:
>dat1<-transform(dat,f = a/median(a),x_new = x*f)
>But gets error reply which says that "f" is not exits since dat has no variables called "f".
>
>So I have to do through 2 steps:
>dat0<-transform(dat,f=a/median(a))
>dat1<-transform(dat0,x_new=x*f)
>
>How to do it through 1 step?
>
>Many thanks!
>
>
> [[alternative HTML version deleted]]
>
>______________________________________________
>R-help@r-project.org mailing list
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>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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