From: <luke_at_stat.uiowa.edu>

Date: Tue, 02 Jun 2009 10:28:20 -0500 (CDT)

Date: Tue, 02 Jun 2009 10:28:20 -0500 (CDT)

Thanks for the report. Should be fixed in teh devel and 2.9 branches.

luke

On Mon, 1 Jun 2009, William Dunlap wrote:

> It looks like the 'seq' variable to 'for' can be altered from

*> within the loop, leading to incorrect answers. E.g., in
**> the following I'd expect 'sum' to be 1+2=3, but R 2.10.0
**> (svn 48686) gives 44.5.
**>
**> > x = c(1,2); sum = 0; for (i in x) { x[i+1] = i + 42.5; sum = sum +
**> i }; sum
**> [1] 44.5
**> or, with a debugging cat()s,
**> > x = c(1,2); sum = 0; for (i in x) { cat("before, i=", i, "\n");
**> x[i+1] = i + 42.5; cat("after, i=", i,"\n"); sum = sum + i }; sum
**> before, i= 1
**> after, i= 1
**> before, i= 43.5
**> after, i= 43.5
**> [1] 44.5
**>
**> If I force the for's 'seq' to be a copy of x by adding 0 to it, then I
**> do get the expected answer.
**>
**> > x = c(1,2); sum = 0; for (i in x+0) { x[i+1] = i + 42.5; sum = sum
**> + i }; sum
**> bbbbb[1] 3
**>
**> It looks like an error in reference counting.
**>
**> Bill Dunlap
**> TIBCO Software Inc - Spotfire Division
**> wdunlap tibco.com
**>
**> ______________________________________________
**> R-devel_at_r-project.org mailing list
**> https://stat.ethz.ch/mailman/listinfo/r-devel
**>
*

-- Luke Tierney Chair, Statistics and Actuarial Science Ralph E. Wareham Professor of Mathematical Sciences University of Iowa Phone: 319-335-3386 Department of Statistics and Fax: 319-335-3017 Actuarial Science 241 Schaeffer Hall email: luke_at_stat.uiowa.edu Iowa City, IA 52242 WWW: http://www.stat.uiowa.edu ______________________________________________ R-devel_at_r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-develReceived on Tue 02 Jun 2009 - 16:03:22 GMT

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