Python error No handles with labels found to put in legend with matplotlib

Question

No handles with labels found to put in legend has an initial answer for this question, but the solution to use ax.legend() is not working for us

Reproducible example:

test_data = pd.DataFrame.from_dict({'x': {0: 9.480850219726562, 1: 14.477883338928223, 2: 5.063024044036865, 3: 11.274681091308594, 4: 5.3310112953186035}, 'y': {0: 1.3540315628051758, 1: 9.007585525512695, 2: 7.3623576164245605, 3: 7.365053653717041, 4: 6.734741687774658}, 'labels': {0: 71, 1: 26, 2: 42, 3: -1, 4: -1}})
test_data.head()

fig, ax = plt.subplots(figsize=(20, 10))
plt.scatter(test_data.x, test_data.y, cmap='hsv_r')
ax.legend()

What is wrong in the above code that ax.legend() is not showing?

Answer 1

You need to capture your handles and pass it to ax.legend along with a label:

test_data = pd.DataFrame.from_dict({'x': {0: 9.480850219726562, 1: 14.477883338928223, 2: 5.063024044036865, 3: 11.274681091308594, 4: 5.3310112953186035}, 'y': {0: 1.3540315628051758, 1: 9.007585525512695, 2: 7.3623576164245605, 3: 7.365053653717041, 4: 6.734741687774658}, 'labels': {0: 71, 1: 26, 2: 42, 3: -1, 4: -1}})
test_data.head()

fig, ax = plt.subplots(figsize=(20, 10))
d = plt.scatter(test_data.x, test_data.y, cmap='hsv_r')
ax.legend([d],['dots'])

Output: