Le 19/04/2018 à 09:30, Tomas Kalibera a écrit :
On 04/19/2018 02:06 AM, Duncan Murdoch wrote:
On 18/04/2018 5:08 PM, Tousey, Colton wrote:
Hello,
I want to report a bug in R that is limiting my capabilities to
export a matrix with write.csv or write.table with over
2,147,483,648 elements (C's int limit). I found this bug already
reported about before:
https://bugs.r-project.org/bugzilla/show_bug.cgi?id=17182. However,
there appears to be no solution or fixes in upcoming R version
releases.
The error message is coming from the writetable part of the utils
package in the io.c source
code(https://svn.r-project.org/R/trunk/src/library/utils/src/io.c):
/* quick integrity check */
if(XLENGTH(x) != (R_len_t)nr * nc)
error(_("corrupt matrix -- dims not not match
length"));
The issue is that nr*nc is an integer and the size of my matrix, 2.8
billion elements, exceeds C's limit, so the check forces the code to
fail.
Yes, looks like a typo: R_len_t is an int, and that's how nr was
declared. It should be R_xlen_t, which is bigger on machines that
support big vectors.
I haven't tested the change; there may be something else in that
function that assumes short vectors.
Indeed, I think the function won't work for long vectors because of
EncodeElement2 and EncodeElement0. EncodeElement2/0 would have to be
changed, including their signatures
That would be a definite fix but before such deep rewriting is
undertaken may the following small fix (in addition to "(R_xlen_t)nr *
nc") will be sufficient for cases where nr and nc are in int range but
their product can reach long vector limit:
replace
tmp = EncodeElement2(x, i + j*nr, quote_col[j], qmethod,
&strBuf, sdec);
by
tmp = EncodeElement2(VECTOR_ELT(x, (R_xlen_t)i + j*nr), 0,
quote_col[j], qmethod,
&strBuf, sdec);
Serguei
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