[R] Using paste to create and evaluate a variable expression

[arun]

Hi,
Try this:
expr1<-parse(text=paste(paste0("X",1:2),collapse="+"))
 eval(expr1)
#[1] 7 7 7 7 7 7
A.K.




----- Original Message -----
From: Bryan Keller <bsbkeller at gmail.com>
To: r-help at r-project.org
Cc: 
Sent: Monday, September 17, 2012 12:04 AM
Subject: [R] Using paste to create and evaluate a variable expression

Is it possible to use "paste" to write out an expression and evaluate it?
Suppose I want to add two vectors X1 and X2, defined as follows:

X1 <- 1:6
X2 <- 6:1

If I write the following it looks like what I want but is a character:
noquote(paste(paste("X", 1, sep = ""), paste("X", 2, sep = ""), sep = "+"))

Is there a way to tell R that I want to evaluate the text, not just print
it out as a character?

Bryan

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