unable to load shared object - opencv

Hi all

i'm trying to use the opencv's function into R.

i wrote a simple script, just for try to understand how use c++ in R, it
loads an image and write it with a different name (i know it ), and then
write "Hello, World". The file is names prova2.cpp (is the first time i try
to use c++ )

#include <stdio.h>
#include <opencv/cv.h>
#include <opencv2/core/core.hpp>
#include <opencv2/highgui/highgui.hpp>
#include <opencv/highgui.h>
#include <opencv/cv.h> 
#include <R.h>
#include <Rinternals.h>

extern "C" SEXP provaR(void) {
cv::Mat gravit;
gravit=cv::imread("imm.jpg");
cv::imwrite("imm_dop.jpg",gravit);
Rprintf("Hello, World!nn");
return R_NilValue;
}

Now in the terminal  i type R CMD SHLIB  prova2.cpp to create the file
prova2.so and this happen without error.

In R i type dyn.load("prova2.so") and get this error:

Errore in dyn.load("prova2.so") : 
 unable to load shared object
'/Users/niandra/Desktop/statistico/r/builtpack/ProvaScript/prova2.so':

dlopen(/Users/niandra/Desktop/statistico/r/builtpack/ProvaScript/prova2.so,
6): Symbol not found: __ZN2cv11_InputArrayC1ERKNS_3MatE
 Referenced from:
/Users/niandra/Desktop/statistico/r/builtpack/ProvaScript/prova2.so
 Expected in: flat namespace
in /Users/niandra/Desktop/statistico/r/builtpack/ProvaScript/prova2.so

I understand that the problem is because i should tell R where to find the
opencv library, but i really don't know how do it.

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On 8 November 2012 at 12:53, niandra wrote:
| Edit
| 
| i try to use this comman in terminal:
| R CMD SHLIB  prova2.cpp -l/usr/local/lib -l/usr/local/include
| -l/System/Library/Frameworks  and gave me this error

You may want to go back to some introduction to Unix and its toolchains and
revisit the differences between

   -I

   -L

   -l

They may look the same, especially with a typewriter font, but trust me that
they are not.

Dirk

-- 
Dirk Eddelbuettel | edd at debian.org | http://dirk.eddelbuettel.com

Sorry but i'm really a beginner.

If when i use opencv with Xcode i need to set the following path 
/System/Library/Frameworks
/usr/local/include
/usr/local/lib 

how can i specify this in  R CMD SHLIB?

On Nov 8, 2012, at 3:34 PM, niandra wrote:

Sorry but i'm really a beginner.

If when i use opencv with Xcode i need to set the following path 
/System/Library/Frameworks
/usr/local/include
/usr/local/lib 

how can i specify this in  R CMD SHLIB?

Those are essentially default so no need to specify any of those. The real thing you need to specify are the actual libraries to link against, typically something like -lopencv_core ... If you use a framework it may be just something like -framework OpenCV - we don't know since you didn't tell us what your'e really using.

On Nov 8, 2012, at 3:34 PM, niandra wrote:

Sorry but i'm really a beginner.

If when i use opencv with Xcode i need to set the following path 
/System/Library/Frameworks
/usr/local/include
/usr/local/lib 

how can i specify this in  R CMD SHLIB?

Those are essentially default so no need to specify any of those. The real thing you need to specify are the actual libraries to link against, typically something like -lopencv_core ... If you use a framework it may be just something like -framework OpenCV - we don't know since you didn't tell us what your'e really using.