如何在 plot 中制作图例？

Question

I am unable to figure out a way to get a legend of my plot. My data is a data frame consisting of 3 columns x, y and z. x and y represent the co-ordinates of a point and z is the label(0,1,2,3) that the point belongs to. Sample data:

I need to plot a scatterplot with a legend containing a colour representing a respective label. I have plotted the scatterplot but am unable to understand how to put the legend in it. The code I used till now is(dft is the dataframe):

import matplotlib.pyplot as plt
%matplotlib inline
fig = plt.figure(figsize=(8,8))
ax = fig.add_subplot()
ax.scatter(dft['x'] , dft['y'], c=dft['z'], cmap = 'hsv')
plt.show()

The figure I obtained is:

I need a legend for each color.

Answer 1

You can try this code instead:

import matplotlib.pyplot as plt
%matplotlib inline
plt.figure(figsize=(8,8))
plt.scatter(dft['x'] , dft['y'], c=dft['z'], cmap = 'hsv')
plt.colorbar()