Message-ID: <1356358536.66452.YahooMailNeo@web142603.mail.bf1.yahoo.com>
Date: 2012-12-24T14:15:36Z
From: arun
Subject: How to do it through 1 step?
In-Reply-To: <776644c0.13bba.13bcc75ee97.Coremail.laomeng_3@163.com>
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 <laomeng_3 at 163.com>
To: arun <smartpink111 at yahoo.com>
Cc: R help <r-help at 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?<smartpink111 at 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?<laomeng_3 at 163.com>
>To:?r-help at 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]]
>
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