matplotlib的annotate用法小结

这个是matplotlib自定义的annotate方法的文本：

一、

     def annotate(self, s, xy, *args, **kwargs):
         a = mtext.Annotation(s, xy, *args, **kwargs)
         a.set_transform(mtransforms.IdentityTransform())
         if 'clip_on' in kwargs:
             a.set_clip_path(self.patch)
         self._add_text(a)
         return a

这个方法里面定义了annotate方法所使用的变量，其中*args是tuple，**kwargs是dict

二、

def __init__(self, s, xy,
                 xytext=None,
                 xycoords='data',
                 textcoords=None,
                 arrowprops=None,
                 annotation_clip=None,
                 **kwargs):
        """
        Annotate the point *xy* with text *s*.
        在点xy:（x,y）处注释文本  s
        In the simplest form, the text is placed at *xy*.
        在最简单的形式中，文本是处在xy的坐标点处
        Optionally, the text can be displayed in another position *xytext*.实际应用中，文本用xytext属性来随意定义文本所在的位置
        An arrow pointing from the text to the annotated point *xy* can then
        be added by defining *arrowprops*.  可以增加从文本到注释点xy的箭头指向，箭头样式通过arrowprops属性定义

        Parameters
        ----------
        s : str
            The text of the annotation.
	s:str类型，注释的文本
        xy : (float, float)
            The point *(x,y)* to annotate.
	xy: (float, float)坐标点，所要注释所在的坐标点
        xytext : (float, float), optional
            The position *(x,y)* to place the text at.
            If *None*, defaults to *xy*.
	xytext:(float, float)坐标点，可选，注释文本所在的坐标点，默认是上面xy的坐标点
        xycoords : str, `.Artist`, `.Transform`, callable or tuple, optional
	xycoords :str类型，Artist和Transform的matplotlib基类，元组，可选
            The coordinate system that *xy* is given in. The following types
            of values are supported:
	    给定的xy坐标系统是由属性xycoords来提供支持，该属性以下值
            - One of the following strings:

              =================   =============================================
              Value               Description
              =================   =============================================
              'figure points'     Points from the lower left of the figure 距离图层左下角的点数量，比如xy=(10,10)说明距离图层左下方各10个点的位置
              'figure pixels'     Pixels from the lower left of the figure 距离图层左下角的像素，比如xy=(10,10)说明距离图层左下方各10个像素的位置
              'figure fraction'   Fraction of figure from lower left 距离图层左下角的数字分数，也就是百分比。左下角是（0，0），右上角是（1,1）。如果xy=(0.5,0.6)，也就是距离左下角横坐标50%，纵坐标60%
              'axes points'       Points from lower left corner of axes  距离轴坐标左下角的点数量
              'axes pixels'       Pixels from lower left corner of axes  距离轴坐标左下角的像素
              'axes fraction'     Fraction of axes from lower left       距离轴坐标左下角的数字分数
              'data'              Use the coordinate system of the object being
                                  annotated (default)                    使用实际的轴坐标的数据（默认）
              'polar'             *(theta,r)* if not native 'data' coordinates   使用极坐标系来处理，（弧度，长度）
              =================   =============================================

            - An `.Artist`: *xy* is interpreted as a fraction of the artists
              `~matplotlib.transforms.Bbox`. E.g. *(0, 0)* would be the lower
              left corner of the bounding box and *(0.5, 1)* would be the
              center top of the bounding box.

            - A `.Transform` to transform *xy* to screen coordinates.

            - A function with one of the following signatures::

                def transform(renderer) -> Bbox
                def transform(renderer) -> Transform

              where *renderer* is a `.RendererBase` subclass.

              The result of the function is interpreted like the `.Artist` and
              `.Transform` cases above.

            - A tuple *(xcoords, ycoords)* specifying separate coordinate
              systems for *x* and *y*. *xcoords* and *ycoords* must each be
              of one of the above described types.

            See :ref:`plotting-guide-annotation` for more details.

            Defaults to 'data'.

        textcoords : str, `.Artist`, `.Transform`, callable or tuple, optional
            The coordinate system that *xytext* is given in.
       textcoords :str类型，Artist和Transform的matplotlib基类，元组，可选,其值是与'xycoords'一致，并且也可以使用下面两个值《主要定义偏移量的》，如果没有说明，则与'xycoords'使用的坐标系统一致
            All *xycoords* values are valid as well as the following
            strings:

            =================   =========================================
            Value               Description
            =================   =========================================
            'offset points'     Offset (in points) from the *xy* value
            'offset pixels'     Offset (in pixels) from the *xy* value
            =================   =========================================

            Defaults to the value of *xycoords*, i.e. use the same coordinate
            system for annotation point and text position.

        arrowprops : dict, optional
            The properties used to draw a
            `~matplotlib.patches.FancyArrowPatch` arrow between the
            positions *xy* and *xytext*.
	arrowprops : 字典类，可选。这个属性主要是用来画出xytext的文本坐标点到xy注释点坐标点的箭头指向线段
            If *arrowprops* does not contain the key 'arrowstyle' the
            allowed keys are:
	如果arrowprops 字典类中不包含arrowstyle的key，则可以使用下列的KEY
            ==========   ======================================================
            Key          Description
            ==========   ======================================================
            width        The width of the arrow in points                       宽度：以点为单位定义连线的宽度
            headwidth    The width of the base of the arrow head in points      箭头宽度：以点为单位定义箭头的宽度
            headlength   The length of the arrow head in points                 箭头长度：以点为单位定义箭头的长度
            shrink       Fraction of total length to shrink from both ends      缩小:移动提示，并使其离注释点和文本一些距离
            ?            Any key to :class:`matplotlib.patches.FancyArrowPatch`  其他的matplotlib.patches.FancyArrowPatch基类中属性
            ==========   ======================================================

            If *arrowprops* contains the key 'arrowstyle' the
            above keys are forbidden.  The allowed values of
            ``'arrowstyle'`` are:
	如果arrowprops 字典类中包含arrowstyle的key，则可以使用下列的赋值
            ============   =============================================
            Name           Attrs
            ============   =============================================
            ``'-'``        None
            ``'->'``       head_length=0.4,head_width=0.2
            ``'-['``       widthB=1.0,lengthB=0.2,angleB=None
            ``'|-|'``      widthA=1.0,widthB=1.0
            ``'-|>'``      head_length=0.4,head_width=0.2
            ``'<-'``       head_length=0.4,head_width=0.2
            ``'<->'``      head_length=0.4,head_width=0.2
            ``'<|-'``      head_length=0.4,head_width=0.2
            ``'<|-|>'``    head_length=0.4,head_width=0.2
            ``'fancy'``    head_length=0.4,head_width=0.4,tail_width=0.4
            ``'simple'``   head_length=0.5,head_width=0.5,tail_width=0.2
            ``'wedge'``    tail_width=0.3,shrink_factor=0.5
            ============   =============================================

            Valid keys for `~matplotlib.patches.FancyArrowPatch` are:

            ===============  ==================================================
            Key              Description
            ===============  ==================================================
            arrowstyle       the arrow style                     	箭头的样式
            connectionstyle  the connection style                       连接线的样式
            relpos           default is (0.5, 0.5)                      箭头起始点相对注释文本的位置，默认为 (0.5, 0.5)，即文本的中心，
                                                                       （0，0）表示左下角，（1，1）表示右上角
            patchA           default is bounding box of the text        箭头起点处的图形（matplotlib.patches对象），默认是注释文字框
            patchB           default is None                            箭头终点处的图形（matplotlib.patches对象），默认为空
            shrinkA          default is 2 points                        箭头起点的缩进点数，默认为2
            shrinkB          default is 2 points                         箭头终点的缩进点数，默认为2
            mutation_scale   default is text size (in points)
            mutation_aspect  default is 1.
            ?                any key for :class:`matplotlib.patches.PathPatch`   其他matplotlib.patches.PathPatch的属性
            ===============  ==================================================

            Defaults to None, i.e. no arrow is drawn.    默认是NONE，没有任何箭头绘制

        annotation_clip : bool or None, optional            annotation_clip : 布尔值或者NONE，可选
            Whether to draw the annotation when the annotation point *xy* is   当注释点xy在子图区域外面是否要绘制注释
            outside the axes area.

            - If *True*, the annotation will only be drawn when *xy* is       设为True时，只有被注释点在子图区内时才绘制注释；
              within the axes.
            - If *False*, the annotation will always be drawn.               设为False时，无论被注释点在哪里都绘制注释。
            - If *None*, the annotation will only be drawn when *xy* is      NONE：仅当xycoords为‘data’时，相当于True。
              within the axes and *xycoords* is 'data'.

            Defaults to *None*.

        **kwargs
            Additional kwargs are passed to `~matplotlib.text.Text`.

        Returns
        -------
        annotation : `.Annotation`

        See Also
        --------
        :ref:`plotting-guide-annotation`.

        """
        _AnnotationBase.__init__(self,
                                 xy,
                                 xycoords=xycoords,
                                 annotation_clip=annotation_clip)
        # warn about wonky input data