vw cffi example

gistfile1.txt

from cffi import FFI


# create ffi wrapper object
ffi = FFI()
ffi.cdef('''
    void* VW_InitializeA(char *);
    
    void* VW_ReadExampleA(void*, char*);
    
    float VW_Learn(void*, void*);
    
    void VW_FinishExample(void*, void*);
    
    void VW_Finish(void*);
    ''')
ffilib = ffi.verify('''
    typedef short char16_t;
    #define bool int
    #define true (1)
    #define false (0)
    
    #include "vwdll.h"
    ''',
                    include_dirs=['/usr/local/include/vowpalwabbit', './vw_cffi', '/usr/include', '.'],
                    library_dirs=['/usr/lib', '/usr/lib64'],
                    libraries=['vw_c_wrapper', "vw", "allreduce"],
                    ext_package='vw'
                    )

class VWModel(object):
    def __init__(self, params_str):
        self._vw = ffilib.VW_InitializeA(params_str)
        if not self._vw:
            raise VWModelError("VW Model failed to init")

    def getScore(self, example_str):
        example = ffilib.VW_ReadExampleA(self._vw, example_str)
        score = ffilib.VW_Learn(self._vw, example)
        ffilib.VW_FinishExample(self._vw, example)
        return score

    def close(self):
        if self._vw:
            ffilib.VW_Finish(self._vw)
            self._vw = None

def __del__(self):
    self.close()

if __name__ == "__main__":
    vw_model = VWModel("-b29 -t -i %s -q pm -q po -q pw -q pf -q ps --quiet" % "./magnetic_ctr_prediction_vw_incremental_build.vw")
    score = vw_model.getScore("| w Chrome 31.0.1650 |c 909 |a 22-05 |y USA |b 6941 |z 728x90 |e n |f 0 |k  |m n-1357 |o Windows Vista |p youtube.com |r OH |s 3287 ")
    print score
    vw_model.close()