Initialize data from a CSC matrix.

def _init_from_csc(self, csc):
        """
        Initialize data from a CSC matrix.
        """
        if len(csc.indices) != len(csc.data):
            raise ValueError('length mismatch: {} vs {}'.format(len(csc.indices), len(csc.data)))
        self.handle = ctypes.c_void_p()
        _check_call(_LIB.XGDMatrixCreateFromCSC(c_array(ctypes.c_ulong, csc.indptr),
                                                c_array(ctypes.c_uint, csc.indices),
                                                c_array(ctypes.c_float, csc.data),
                                                len(csc.indptr), len(csc.data),
                                                ctypes.byref(self.handle)))