[R] Creating a new column to a data frame using a formula from another variable

[arun]

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..