Re: [R] Evaluating a string

2010-07-02 Thread Joshua Wiley
Hello Jonathan,

You can use eval() and parse(), although there may be better ways of
getting to your end goal (assuming you have not inherited a series of
character strings held in objects that should be run as commands).  At
any rate, this works:

a - 3
b - 2
operator - -
statement_string - paste(a, operator, b, sep=)
eval(parse(text = statement_string))

Best regards,

Josh


On Thu, Jul 1, 2010 at 2:54 PM, Jonathan Greenberg
greenb...@ucdavis.edu wrote:
 Rhelpers:

 How do I get R to evaluate a string, as if it was an R statement, e.g.:

 a=3
 b=2
 operator=-
 statement_string=paste(a,operator,b,sep=)

 --j

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 R-help@r-project.org mailing list
 https://stat.ethz.ch/mailman/listinfo/r-help
 PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
 and provide commented, minimal, self-contained, reproducible code.




-- 
Joshua Wiley
Ph.D. Student, Health Psychology
University of California, Los Angeles
http://www.joshuawiley.com/

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R-help@r-project.org mailing list
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.


Re: [R] Evaluating a string

2010-07-02 Thread David Winsemius


On Jul 2, 2010, at 2:05 AM, Joshua Wiley wrote:


Hello Jonathan,

You can use eval() and parse(), although there may be better ways of
getting to your end goal



 do.call(operator, list(a,b))
[1] 1



(assuming you have not inherited a series of
character strings held in objects that should be run as commands).  At
any rate, this works:

a - 3
b - 2
operator - -
statement_string - paste(a, operator, b, sep=)
eval(parse(text = statement_string))

Best regards,

Josh


On Thu, Jul 1, 2010 at 2:54 PM, Jonathan Greenberg
greenb...@ucdavis.edu wrote:

Rhelpers:

How do I get R to evaluate a string, as if it was an R statement,  
e.g.:


a=3
b=2
operator=-
statement_string=paste(a,operator,b,sep=)

--j



David Winsemius, MD
West Hartford, CT

__
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.


[R] Evaluating a string

2010-07-01 Thread Jonathan Greenberg
Rhelpers:

How do I get R to evaluate a string, as if it was an R statement, e.g.:

a=3
b=2
operator=-
statement_string=paste(a,operator,b,sep=)

--j

__
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.