R help - Sep 2013 - Creating a new column to a data frame using a formula from another variable

Hi,

Change:
aa$z<-? eval(parse(text=bb))

?aa
#? x y? z
#1 2 3? 3
#2 4 5? 7
#3 6 7 11
A.K.

I want to create a new column to a data frame using a formula from another
variable:
Example: 
I have a data set "aa" is; 
x ? ?y 
2 ? ?3 
4 ? ?5 
6 ? ?7 

My R code is; 
>bb <- "x+y-2" 
>attach(aa) 
>aa$z<- bb 
>detach(aa) 
the result is; 
x ?y ?z 
2 ?3 ?x+y-2 
4 ?5 ?x+y-2 
6 ?7 ?x+y-2 

but I want like; 
x ?y ?z 
2 ?3 ?3 
4 ?5 ?7 
6 ?7 ?11 

Could you please help me..

Also, Instead of ?attach, you could try ?with or ?within
aa$z<- with(aa,eval(parse(text=bb)))
aa$z

#[1]? 3? 7 11

aa<- within(aa,z<- eval(parse(text=bb)))
aa
#? x y? z
#1 2 3? 3
#2 4 5? 7
#3 6 7 11
A.K.



----- Original Message -----
From: arun <smartpink111 at yahoo.com>
To: R help <r-help at r-project.org>
Cc: 
Sent: Wednesday, September 25, 2013 8:47 AM
Subject: Re: Re: Creating a new column to a data frame using a formula from
another variable

Hi,

Change:
aa$z<-? eval(parse(text=bb))

?aa
#? x y? z
#1 2 3? 3
#2 4 5? 7
#3 6 7 11
A.K.

I want to create a new column to a data frame using a formula from another
variable:
Example: 
I have a data set "aa" is; 
x ? ?y 
2 ? ?3 
4 ? ?5 
6 ? ?7 

My R code is; 
>bb <- "x+y-2" 
>attach(aa) 
>aa$z<- bb 
>detach(aa) 
the result is; 
x ?y ?z 
2 ?3 ?x+y-2 
4 ?5 ?x+y-2 
6 ?7 ?x+y-2 

but I want like; 
x ?y ?z 
2 ?3 ?3 
4 ?5 ?7 
6 ?7 ?11 

Could you please help me..