In the maps library, NA's are inserted between polygons so lines() can
be used to draw all polygons at once. The code to do it is like this:
*x++ = NA_REAL;
*y++ = NA_REAL;
where x and y are declared as
double *x, *y, *range;
and are the arguments passed in through a .C call.
However, the values show up in R as -6.62314033633867e-229 instead of
NA, so the drawing gets messed up.
Any suggestions as to what might be going wrong?
This is happening in Windows, using gcc 2.95.2, R source 1.3.1,
platform i386-pc-mingw32.
Duncan Murdoch
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Setting NA from C code
2 messages · Duncan Murdoch, Brian Ripley
On Mon, 5 Nov 2001, Duncan Murdoch wrote:
In the maps library, NA's are inserted between polygons so lines() can
be used to draw all polygons at once. The code to do it is like this:
*x++ = NA_REAL;
*y++ = NA_REAL;
where x and y are declared as
double *x, *y, *range;
and are the arguments passed in through a .C call.
However, the values show up in R as -6.62314033633867e-229 instead of
NA, so the drawing gets messed up.
Any suggestions as to what might be going wrong?
You are probably not importing R_NaReal, which is what NA_REAL is a macro reference to. That's the point of globalvars.h, which the standard Makefile forces to be included. This will not be needed from 1.4.0 on.
This is happening in Windows, using gcc 2.95.2, R source 1.3.1, platform i386-pc-mingw32. Duncan Murdoch -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-devel mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html Send "info", "help", or "[un]subscribe" (in the "body", not the subject !) To: r-devel-request@stat.math.ethz.ch _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._
Brian D. Ripley, ripley@stats.ox.ac.uk Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ University of Oxford, Tel: +44 1865 272861 (self) 1 South Parks Road, +44 1865 272860 (secr) Oxford OX1 3TG, UK Fax: +44 1865 272595 -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-devel mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html Send "info", "help", or "[un]subscribe" (in the "body", not the subject !) To: r-devel-request@stat.math.ethz.ch _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._