def positive_directional_movement(high_data, low_data):
    """
    Positive Directional Movement (+DM).

    Formula:
    +DM: if UPMOVE > DWNMOVE and UPMOVE > 0 then +DM = UPMOVE else +DM = 0
    """
    catch_errors.check_for_input_len_diff(high_data, low_data)
    up_moves = calculate_up_moves(high_data)
    down_moves = calculate_down_moves(low_data)

    pdm = []
    for idx in range(0, len(up_moves)):
        if up_moves[idx] > down_moves[idx] and up_moves[idx] > 0:
            pdm.append(up_moves[idx])
        else:
            pdm.append(0)

    return pdm