Is There a Matplotlib Equivalent of Matlab's Datacursormode

Label for point in plots in matplotlib

If you look at the rest of the code in __call__ you'll see xdata and ydata are never used. You can simply delete the line

xdata, ydata = event.artist.get_data()

and the rest of Joe's beautiful code works just fine.

Add cursor to matplotlib

There is an example on the matplotlib page, which you may adapt to show a point at the position of interest.

import matplotlib.pyplot as plt
import matplotlib.widgets as widgets
import numpy as np

class SnaptoCursor(object):
    def __init__(self, ax, x, y):
        self.ax = ax
        self.ly = ax.axvline(color='k', alpha=0.2)  # the vert line
        self.marker, = ax.plot([0],[0], marker="o", color="crimson", zorder=3) 
        self.x = x
        self.y = y
        self.txt = ax.text(0.7, 0.9, '')

    def mouse_move(self, event):
        if not event.inaxes: return
        x, y = event.xdata, event.ydata
        indx = np.searchsorted(self.x, [x])[0]
        x = self.x[indx]
        y = self.y[indx]
        self.ly.set_xdata(x)
        self.marker.set_data([x],[y])
        self.txt.set_text('x=%1.2f, y=%1.2f' % (x, y))
        self.txt.set_position((x,y))
        self.ax.figure.canvas.draw_idle()

t = np.arange(0.0, 1.0, 0.01)
s = np.sin(2*2*np.pi*t)
fig, ax = plt.subplots()

#cursor = Cursor(ax)
cursor = SnaptoCursor(ax, t, s)
cid =  plt.connect('motion_notify_event', cursor.mouse_move)

ax.plot(t, s,)
plt.axis([0, 1, -1, 1])
plt.show()

Python and Remove annotation from figure

Most matplotlib objects have a remove() function (I think it is inherited from Artist). Just call that on the object you want to remove.

Edit:

If you have

dc = DataCursor(...) # what ever aruguements you give it
# bunch of code
dc.annotation.remove()
del dc
plt.draw() # need to redraw to make remove visible

Python has no notion of 'private' attributes, so you can just reach inside you object and call remove on the annotation. See tutorial on classes for more details.

The down side of this is that now you have an object is a strange state. If you have any other references to it, they might behave badly. If you want to keep the DataCursor object around you can modify the annotation object using it's set_* functions or change it's visibility to temporarily hide it (doc)

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