Using paste to create and evaluate a variable expression
On Sep 17, 2012, at 06:04 , Bryan Keller wrote:
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?
You need to parse() it first, then eval()uate. (Read the respective help pages for details.) However:
fortune("parse")
If the answer is parse() you should usually rethink the question.
-- Thomas Lumley
R-help (February 2005)
Peter Dalgaard, Professor, Center for Statistics, Copenhagen Business School Solbjerg Plads 3, 2000 Frederiksberg, Denmark Phone: (+45)38153501 Email: pd.mes at cbs.dk Priv: PDalgd at gmail.com