On Sep 11, 2010, at 10:04 AM, Martin Maechler wrote:
"SW" == Samuel Wuest <wue...@tcd.ie>
on Thu, 26 Aug 2010 14:34:26 +0100 writes:
SW> Hi Greg,
SW> thanks for the suggestion:
SW> I have attached some small dataset that can be used to
reproduce the
SW> odd behavior of the approxfun-function.
SW> If it gets stripped off my email, it can also be downloaded at:
SW> http://bioinf.gen.tcd.ie/approx.data.Rdata
SW> Strangely, the problem seems specific to the data structure
in my
SW> expression set, when I use simulated data, everything worked
fine.
SW> Here is some code that I run and resulted in the strange
output that I
SW> have described in my initial post:
### load the data: a list called approx.data
load(file="approx.data.Rdata")
### contains the slots "x", "y", "input"
names(approx.data)
SW> [1] "x" "y" "input"
### with y ranging between 0 and 1
range(approx.data$y)
SW> [1] 0 1
### compare ranges of x and input-x values (the latter is a small
subset of 500 data points):
range(approx.data$x)
SW> [1] 3.098444 7.268812
range(approx.data$input)
SW> [1] 3.329408 13.026700
### generate the interpolation function (warning message benign)
interp <- approxfun(approx.data$x, approx.data$y, yleft=1,
yright=0, rule=2)
SW> Warning message:
SW> In approxfun(approx.data$x, approx.data$y, yleft = 1, yright
= 0, :
SW> collapsing to unique 'x' values
### apply to input-values
y.out <- sapply(approx.data$input, interp)
### still I find output values >1, even though yleft=1:
range(y.out)
SW> [1] 0.000000 7.207233
#-------------- on another 64 bit Mac -------------
> load(file="approx.data.Rdata")
> names(approx.data)
[1] "x" "y" "input"
> range(approx.data$y)
[1] 0 1
> range(approx.data$x)
[1] 3.098444 7.268812
>
> interp <- approxfun(approx.data$x, approx.data$y, yleft=1,
yright=0, rule=2)
Warning message:
In approxfun(approx.data$x, approx.data$y, yleft = 1, yright = 0, :
collapsing to unique 'x' values
> y.out <- sapply(approx.data$input, interp)
> range(y.out)
[1] -5.143958e+284 9.816907e-01
> interp
function (v)
.C("R_approxfun", as.double(x), as.double(y), as.integer(n),
xout = as.double(v), as.integer(length(v)), as.integer(method),
as.double(yleft), as.double(yright), as.double(f), NAOK = TRUE,
PACKAGE = "stats")$xout
<environment: 0x1598c91b8>
# attempt to offer yright and yledft in the sapply call failed
> y.out <- sapply(approx.data$input, interp, yright=0, yleft=1)
Error in FUN(c(6.99984458535897, 4.85139079147721, 7.58922165833,
10.8135863246057, :
unused argument(s) (yright = 0, yleft = 1)
#Create yright and yleft in the calling environment:
> yright=0; yleft=1
> y.out <- sapply(approx.data$input, interp)
> range(y.out)
[1] 0.0000000 0.9816907
Now it "works" as expected.
It seems to me that the yleft and yright values may not be properly
incorporated into the constructed function.
> sessionInfo()
R version 2.11.1 Patched (2010-06-14 r52281)
x86_64-apple-darwin9.8.0
locale:
[1] en_US.UTF-8/en_US.UTF-8/C/C/en_US.UTF-8/en_US.UTF-8
attached base packages:
[1] grid splines stats graphics grDevices
[6] utils datasets methods base
other attached packages:
[1] gplots_2.8.0 caTools_1.10 bitops_1.0-4.1
[4] gdata_2.8.0 gtools_2.6.2 sos_1.2-9
[7] brew_0.1-1 qpcR_1.3-2 minqa_1.1.9
[10] Rcpp_0.8.5 nlme_3.1-96 cluster_1.12.3
[13] rgl_0.91 minpack.lm_1.1-4 MASS_7.3-6
[16] chron_2.3-35 maps_2.1-4 gmodels_2.15.0
[19] rbenchmark_0.3 data.table_1.5 rms_3.0-0
[22] Hmisc_3.8-1 survival_2.35-8 plyr_1.1
[25] lattice_0.18-8
loaded via a namespace (and not attached):
[1] tools_2.11.1
--
David Winsemius
I get completely different (and correct) results,
by the way the *same* you have in the bug report you've
submitted
(https://bugs.r-project.org/bugzilla3/show_bug.cgi?id=14377)
and which does *not* show any bug:
range(y.out)
[1] 0.0000000 0.9816907
Of course, I do believe that you've seen the above problems,
-- on 64-bit Mac ? as you report in sessionInfo() ? --
but I cannot reproduce them.
And also, you seem yourself to be able to get different results
for the same data... what are the circumstances?
Regards,
Martin Maechler, ETH Zurich
David Winsemius, MD
West Hartford, CT
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