Using matplotlib to label points on a scatter plot

I am trying to use the DataCursor approach (https://stackoverflow.com/a/4674445/1301710) to label points using matplotlib. I have several thousand points and would like to see their label on mouseover. However, there are two differences: one, I'm making a scatter plot and two, I want to label names for each point and not just the x,y coordinates.

here is my code

import os
import matplotlib.pyplot as plt

class DataCursor(object):
text_template = 'x: %0.2f\ny: %0.2f'
x, y = 0.0, 0.0
xoffset, yoffset = -20, 20
text_template = 'x: %0.2f\ny: %0.2f'

def __init__(self, ax, labels,x,y):
    self.ax = ax
self.xlist = x
self.ylist = y
self.labels = labels
    self.annotation = ax.annotate(self.text_template, 
            xy=(self.x, self.y), xytext=(self.xoffset, self.yoffset), 
            textcoords='offset points', ha='right', va='bottom',
            bbox=dict(boxstyle='round,pad=0.5', fc='yellow', alpha=0.5),
            arrowprops=dict(arrowstyle='->', connectionstyle='arc3,rad=0')
            )
    self.annotation.set_visible(False)

def __call__(self, event):
    self.event = event
    xdata, ydata = event.artist.get_data()
    #self.x, self.y = xdata[event.ind], ydata[event.ind]
    self.x, self.y = event.mouseevent.xdata, event.mouseevent.ydata
self.label = self.labels[self.xlist.index(self.x)]
    if self.x is not None:
        self.annotation.xy = self.x, self.y
        self.annotation.set_text(self.label)
        self.annotation.set_visible(True)
        event.canvas.draw()

def process():
#code to make ht_dict here
# ht_dict has the following format: 'ht1' = [nov14count, nov21count] where each key is a string and each value is a list of two integers

print("Start making scatter plot..")
hts = []
nov14 = []
nov21 = []
for key in ht_dict.keys():
    nov14.append(ht_dict[key][0])
    nov21.append(ht_dict[key][1])
hts.append(key)
fig = plt.figure()
scatter = plt.scatter(nov14, nov21)


fig.canvas.mpl_connect('pick_event', DataCursor(plt.gca(), hts, nov14, nov21))
scatter.set_picker(5)
plt.show()  

process()

I am getting the following error though:

AttributeError: 'CircleCollection' object has no attribute 'get_data'

I want to be able to see the string stored in the list hts on mouseover at the x and y coordinates stored in nov14 and nov21 lists respectively at the same indices. I'm not sure what to make of this error and would appreciate any help. Another question I have is (from trying out changes on the existing plot in the DataCursor thread) that using index of to get back label as I am currently doing will give me a value doesn't exist in list error since the clicked on value may not be exactly same as the value in the list. Do you have any suggestions of a better way to display some label/name about a point?

Any guidance or pointers to documentation where I could read up would be appreciated.

Thanks!

Adopting the approach for annotating using the label, given in the examples section on the documentation page of the mpldatacursor, you could do something along these lines (plot a single point with each scatter plot to be able to set an individual label for each point):

import matplotlib.pyplot as plt
from mpldatacursor import datacursor
import random

fig, ax = plt.subplots()
ax.set_title('Click on a dot to display its label')

# Plot a number of random dots
for i in range(1, 1000):
    ax.scatter([random.random()], [random.random()], label='$ID: {}$'.format(i))

# Use a DataCursor to interactively display the label for a selected line...
datacursor(formatter='{label}'.format)

plt.show()

Unfortunately it's rather inefficient, i.e., hardly usable with more than, say, 1000 points.

Result example image: