[R] write.matrix.csr data conversion

[Sam Steingold]

Dear David,

> * David Meyer <zrlreq at grpuavxhz-jvra.ng> [2012-11-06 19:49:15 +0100]:
>
> there is C-code related to *reading* in such a file, but in the
> internal libsvm-format, not the matrix.csr format.

How is the libsvm-format differ from matrix.csr format?
I actually use matrix.csr only because it prints to what libsvm can read.

> There is certainly a way to speed this up, but I am not likely to do
> this in the near future.

too bad.

> On 2012-11-06 19:15, Sam Steingold wrote:
>> David,
>> thanks for adding the feature.
>>
>> read.matrix.csr and, especially, write.matrix.csr are extremely slow:
>>
>>       user    system   elapsed
>>   8381.988  3810.396 12345.349
>>
>> for a 2797634 x 224 matrix I have to deal with.
>>
>> The help page
>> http://rss.acs.unt.edu/Rdoc/library/e1071/html/read.matrix.csr.html
>> says
>>
>> David Meyer (based on C/C++-code by Chih-Chung Chang and Chih-Jen Lin)
>>
>> is there any chance that you might consider replacing the R code with
>> the original C/C++?

-- 
Sam Steingold (http://sds.podval.org/) on Ubuntu 12.04 (precise) X 11.0.11103000
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