def merge_asof(left, right, on=None, left_on=None, right_on=None, left_index=False, right_index=False, by=None, left_by=None, right_by=None, suffixes=('_x', '_y'), tolerance=None, allow_exact_matches=True, direction='backward'):
 op = _AsOfMerge(left, right, on=on, left_on=left_on, right_on=right_on, left_index=left_index, right_index=right_index, by=by, left_by=left_by, right_by=right_by, suffixes=suffixes, how='asof', tolerance=tolerance, allow_exact_matches=allow_exact_matches, direction=direction)
 return op.get_result()

def merge_asof ( left , right , on = None , left_on = None , right_on = None , left_index = False , right_index = False , by = None , left_by = None , right_by = None , suffixes = ( '_x' , '_y' ) , tolerance = None , allow_exact_matches = True , direction = 'backward' ) : op = _AsOfMerge ( left , right , on = on , left_on = left_on , right_on = right_on , left_index = left_index , right_index = right_index , by = by , left_by = left_by , right_by = right_by , suffixes = suffixes , how = 'asof' , tolerance = tolerance , allow_exact_matches = allow_exact_matches , direction = direction ) return op . get_result ( )
perform an asof merge .