panel的dropna方法

文档中如是写：

Panel.dropna(axis=0, how='any', inplace=False)

Drop 2D from panel, holding passed axis constant.

Parameters:	axis : int, default 0 Axis to hold constant. E.g. axis=1 will drop major_axis entries having a certain amount of NA data how : {‘all’, ‘any’}, default ‘any’ ‘any’: one or more values are NA in the DataFrame along the axis. For ‘all’ they all must be. inplace : bool, default False If True, do operation inplace and return None.
Returns:	dropped : Panel