[Rcpp-devel] dyn.load error with particular functor

[nate russell]

Matthew,

Thank you for such a quick response; both of those suggestions worked
perfectly. Out of curiosity, is there any reason to use one of these
implementations over the other - or are they essentially equivalent?

Regards,
Nathan Russell

On Wed, Oct 22, 2014 at 2:10 PM, Matthew Wright <mattw at trdlnk.com> wrote:

> Nate,
>
> The problem here is how you are have implemented your static member of
> trackIdx.  You only declared it.
>
> I'd suggest one of two alternatives:
>
> // add this below the struct declaration.
> int trackIdx::tracker = 0;
>
> Or, just create it in the function where you actually use it instead of
> making it a member.
>     int operator() (std::string x1, std::string x2) {
>       static int tracker;
>       tracker++;
>       return ((s1==x1 && s2==x2) ? (tracker-1) : -1);
>     }
>
>
>
> On Wed, Oct 22, 2014 at 12:39 PM, nate russell <russell.n2012 at gmail.com>
> wrote:
>
>> Hello,
>>
>> I am running into the "Error in dyn.load [...] unable to load shared
>> object ['/tmp/...'] undefined symbol [_...]" error; however it is only
>> happening with one particular Rcpp function, which I find puzzling. Here is
>> my .cpp file containing two functions - I can compile the first one without
>> any issue (in its own file), but the second brings about the noted error
>> message:
>>
>>
>> #include <Rcpp.h>
>> #include <vector>
>> #include <string>
>> #include <algorithm>
>> // [[Rcpp::plugins(cpp11)]]
>>
>> /*
>>  * Works fine.
>>  */
>>
>> struct checkTwo {
>>   public:
>>     checkTwo(const std::string& s1_, const std::string& s2_)
>>     : s1(s1_), s2(s2_) {}
>>     int operator() (std::string x1, std::string x2) {
>>       return (s1==x1 && s2==x2 ? 1 : 0);
>>     }
>>   private:
>>     std::string s1;
>>     std::string s2;
>> };
>>
>> // [[Rcpp::export]]
>> int count_if_if(const Rcpp::DataFrame& df,
>>                 const std::string& c1,
>>                 const std::string& c2)
>> {
>>   std::vector<std::string> vc1 = df["C1"];
>>   std::vector<std::string> vc2 = df["C2"];
>>   int N = df.nrows();
>>
>>   std::vector<int> vcount;
>>   vcount.resize( N );
>>
>>
>> std::transform(vc1.begin(),vc1.end(),vc2.begin(),vcount.begin(),checkTwo(c1,c2));
>>   int total = std::accumulate(vcount.begin(),vcount.end(),0);
>>
>>   return total;
>> }
>>
>> /*
>>  * Does not compile.
>>  */
>>
>> struct trackIdx {
>>   public:
>>     trackIdx(const std::string& s1_, const std::string& s2_)
>>     : s1(s1_),s2(s2_) {}
>>     int operator() (std::string x1, std::string x2) {
>>       tracker++;
>>       return ((s1==x1 && s2==x2) ? (tracker-1) : -1);
>>     }
>>   private:
>>     std::string s1;
>>     std::string s2;
>>     static int tracker;
>> };
>>
>> // [[Rcpp::export]]
>> std::vector<int> mc_index(const Rcpp::DataFrame& df,
>>                           const std::string& c1,
>>                           const std::string& c2)
>> {
>>   std::vector<std::string> vc1 = df["C1"];
>>   std::vector<std::string> vc2 = df["C2"];
>>   int N = df.nrows();
>>
>>   std::vector<int> vcount;
>>   vcount.resize( N );
>>
>>   std::vector<int> result;
>>   result.resize( N );
>>
>>
>> std::transform(vc1.begin(),vc1.end(),vc2.begin(),vcount.begin(),trackIdx(c1,c2));
>>   std::copy_if(vcount.begin(),vcount.end(),result.begin(),
>>     [](int i) -> bool {
>>       return !(i<0);
>>     });
>>
>>   return result;
>> }
>>
>>
>> The above functions (only "count_if_if" at the moment) can be tested like
>> this:
>>
>> Df <- data.frame(
>>   C1=rep(LETTERS[1:4],each=15),
>>   C2=as.character(rep(rep(1:3,each=5),4)),
>>   C3=rep(rep(1:3,each=5),4),
>>   stringsAsFactors=FALSE)
>> ##
>> count_if_if(Df,"B","3")
>> ##
>> # mc_index(Df,"B","3")
>>
>>
>>
>> The exact error message I am getting is:
>>
>> Error in
>> dyn.load("/tmp/Rtmpw7VSkV/sourcecpp_27046ca49cd4/sourceCpp_67600.so") :
>>   unable to load shared object
>> '/tmp/Rtmpw7VSkV/sourcecpp_27046ca49cd4/sourceCpp_67600.so':
>>   /tmp/Rtmpw7VSkV/sourcecpp_27046ca49cd4/sourceCpp_67600.so: undefined
>> symbol: _ZN8trackIdx7trackerE
>>
>>
>> and judging by the last bit, "undefined symbol: _ZN8trackIdx7trackerE",
>> it looks like my "trackIdx" function object is the source of the problem.
>>
>> I have tested this on two different platforms -
>>
>> my network server running CentOS 7:
>>
>> R version 3.1.1
>> Platform: x86_64-redhat-linux-gnu (64-bit)
>> Rcpp_0.11.3
>>
>>
>> and my laptop running Ubuntu 14.04:
>>
>> R version 3.0.2
>> Platform: x86_64-pc-linux-gnu (64-bit)
>> Rcpp_0.11.2
>>
>>
>> Both of these machines use a reasonably up-to-date version of g++ that
>> supports c++11 (although I don't think this has anything to do with the
>> issue). I have never had any problems compiling Rcpp functions on either of
>> these platforms, yet the second function object & Rcpp function above
>> produce the same error on each machine. If anyone can explain what is going
>> wrong and/or suggest how to correct the problem with the above code I would
>> appreciate it very much.
>>
>> Thank you,
>> Nathan Russell
>>
>>
>>
>>
>>
>>
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>> Rcpp-devel at lists.r-forge.r-project.org
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>>
>
>
>
> --
> -------------------------
> Matt Wright
> 312-264-2987 (p)
> 312-479-6821 (m)
>
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