[Rd] bug in approx crashes R

[Vadim Ogranovich]

Thank you Bill.

The original motivation for my experiments with setting yleft to NULL was to see if I could get more flexibility that that allowed by the 'rule' argument. To recall:

    rule: an integer describing how interpolation is to take place
          outside the interval ['min(x)', 'max(x)']. If 'rule' is '1'
          then 'NA's are returned for such points and if it is '2', the
          value at the closest data extreme is used.

What I wanted is to interpolate at the left end, but not at the right end. Still don't know how to do that.

I agree that having a clear error message when yleft, yright, and f are set to non-scalars is better than silently returning NA.

Thanks,
Vadim


-----Original Message-----
From: William Dunlap [mailto:wdunlap at tibco.com]
Sent: Monday, July 27, 2009 12:14 PM
To: Vadim Ogranovich; r-devel at r-project.org
Subject: RE: [Rd] bug in approx crashes R

The C code called by approx (via .C, not .Call), following the help
file,
assumes that yleft and yright are scalars but NULL is not scalar.
The following change would let your example work (returning NA)

--- R/approx.R  (revision 48911)
+++ R/approx.R  (working copy)
@@ -61,8 +61,8 @@
     }
     y <- .C("R_approx", as.double(x), as.double(y), as.integer(nx),
            xout = as.double(xout), as.integer(length(xout)),
-           as.integer(method), as.double(yleft), as.double(yright),
-           as.double(f), NAOK = TRUE, PACKAGE = "stats")$xout
+           as.integer(method), as.double(yleft)[1],
as.double(yright)[1],
+           as.double(f)[1], NAOK = TRUE, PACKAGE = "stats")$xout
     list(x = xout, y = y)
 }

but I think it would be better to get an error message that yleft,
yright, and f are expected to be scalar:

--- R/approx.R  (revision 48911)
+++ R/approx.R  (working copy)
@@ -59,6 +59,7 @@
            stop("'approx' requires n >= 1")
        xout <- seq.int(x[1L], x[nx], length.out = n)
     }
+    stopifnot(length(yleft)==1, length(yright)==1, length(f)==1)
     y <- .C("R_approx", as.double(x), as.double(y), as.integer(nx),
            xout = as.double(xout), as.integer(length(xout)),
            as.integer(method), as.double(yleft), as.double(yright),


Bill Dunlap
TIBCO Software Inc - Spotfire Division
wdunlap tibco.com

> -----Original Message-----
> From: r-devel-bounces at r-project.org
> [mailto:r-devel-bounces at r-project.org] On Behalf Of Vadim Ogranovich
> Sent: Tuesday, July 21, 2009 12:24 PM
> To: 'r-devel at r-project.org'
> Subject: [Rd] bug in approx crashes R
>
> Dear R-devel,
>
> The following line crashes R
> > approx(1, 1, 0, method='const', rule=2, f=0, yleft=NULL,
> ties='ordered')$y
>
> Process R:2 exited abnormally with code 5 at Tue Jul 21 14:18:09 2009
>
>
> > version
>                _
> platform       i386-pc-mingw32
> arch           i386
> os             mingw32
> system         i386, mingw32
> status
> major          2
> minor          9.1
> year           2009
> month          06
> day            26
> svn rev        48839
> language       R
> version.string R version 2.9.1 (2009-06-26)
>
> Thanks,
> Vadim
>
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