在绘制OHLC matplotlib图时，AxesSubplot'对象没有属性'get_xdata'错误

Question

我试图在用户点击有效点时用matplotlib交互式绘制OHLC图。数据存储为表格

的pandas数据帧

index       PX_BID  PX_ASK  PX_LAST  PX_OPEN  PX_HIGH  PX_LOW
2016-07-01  1.1136  1.1137   1.1136   1.1106   1.1169  1.1072
2016-07-04  1.1154  1.1155   1.1154   1.1143   1.1160  1.1098
2016-07-05  1.1076  1.1077   1.1076   1.1154   1.1186  1.1062
2016-07-06  1.1100  1.1101   1.1100   1.1076   1.1112  1.1029
2016-07-07  1.1062  1.1063   1.1063   1.1100   1.1107  1.1053

我正在用matplotlib的烛台功能绘图：

candlestick2_ohlc(ax1, df['PX_OPEN'],df['PX_HIGH'],df['PX_LOW'],df['PX_LAST'],width=1)

绘制时看起来像这样：

我希望控制台打印出点击的点的值，日期以及是打开，高低还是关闭。到目前为止，我有类似的东西：

fig, ax1 = plt.subplots()
ax1.set_picker(True)
ax1.set_title('click on points', picker=True)
ax1.set_ylabel('ylabel', picker=True, bbox=dict(facecolor='red'))

line = candlestick2_ohlc(ax1, df['PX_OPEN'],df['PX_HIGH'],df['PX_LOW'],df['PX_LAST'],width=0.4)

def onpick1(event):
    if isinstance(event.artist, (lineCollection, barCollection)):
        thisline = event.artist
        xdata = thisline.get_xdata()
        ydata = thisline.get_ydata()
        ind = event.ind
        #points = tuple(zip(xdata[ind], ydata[ind]))
        #print('onpick points:', points)
        print( 'X='+str(np.take(xdata, ind)[0]) ) # Print X point
        print( 'Y='+str(np.take(ydata, ind)[0]) ) # Print Y point

fig.canvas.mpl_connect('pick_event', onpick1)
plt.show()

当我运行此图表时，无论在图表上的任何位置点击它都会出现错误：

AttributeError：'AxesSubplot'对象没有属性'get_xdata'。烛台2_ohlc不支持这个吗？

此外，matplotlibs烛台2_ohlc的实例类型是什么，所以我可以检查用户是否点击了实际点？

例如，对于折线图，可以使用检查

isinstance(event.artist,Line2D)

Answer 1

首先，candlestick2_ohlc似乎创建并返回matplotlib.collections.LineCollection实例和matplotlib.collections.PolyCollection实例的元组。

在我们做其他事情之前，我们需要让每个实例都可以选择。

如果您从candlestick2_ohlc返回这些实例时抓取这些实例，则可以轻松使用set_picker：

linecoll, polycoll = candlestick2_ohlc(ax1, df['PX_OPEN'],df['PX_HIGH'],df['PX_LOW'],df['PX_LAST'],width=0.4)

linecoll.set_picker(True)
polycoll.set_picker(True)

我们需要在onpick1函数中检查它们：

import matplotlib.collections as collections

def onpick1(event):

    # Check we have clicked on one of the collections created by candlestick2_ohlc
    if isinstance(event.artist, (collections.LineCollection, collections.PolyCollection)):

        thiscollection = event.artist
        # Find which box or line we have clicked on
        ind = event.ind[0]

        # Find the vertices of the object
        verts = thiscollection.get_paths()[ind].vertices

        if isinstance(event.artist, collections.LineCollection):
            print "Errorbar line dimensions"
        elif isinstance(event.artist, collections.PolyCollection):
            print "Box dimensions"

        # Print the minimum and maximum extent of the object in x and y
        print( "X = {}, {}".format(verts[:, 0].min(), verts[:, 0].max()) )
        print( "Y = {}, {}".format(verts[:, 1].min(), verts[:, 1].max()) )