Hi Alexander,
you could try:
my.string <- "A==1 & B==2"
(my.frame <- data.frame(A=sample(1:2, 20, TRUE), B=sample(1:2, 20, TRUE)))
subset(my.frame, eval(parse(text=my.string)))
I hope it helps.
Best, Dimitris
---- Dimitris Rizopoulos Ph.D. Student Biostatistical Centre School of Public Health Catholic University of Leuven
Address: Kapucijnenvoer 35, Leuven, Belgium Tel: +32/16/336899 Fax: +32/16/337015 Web: http://www.med.kuleuven.ac.be/biostat http://www.student.kuleuven.ac.be/~m0390867/dimitris.htm
----- Original Message ----- From: "Alexander Sokol" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Thursday, November 25, 2004 2:09 PM
Subject: [R] Turning strings into expressions
Hello,
I am running R 1.9.1 om Windows 2000 SP4. My problem is as follows:
Say I have a dataframe my.frame with column names A and B. I have a string,
my.string[1] "A==1 & B==2"
And I would like to retrieve the subset corresponding to my.string, that is,
from my.frame and my.string I would like to get the result of
subset(my.frame,A==1 & B==2)
So I need to find a way to convert
"A==1 & B==2"
to
A==1 & B==2
I at first hoped that get() could do the job, but this does not work. Does
anyone know how to do this?
Thanks, Alexander
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