How to add title to the plot of shap.plots.force with Matplotlib?

Question

I want to add some modifications to my force plot (created by shap.plots.force) using Matplotlib, e.g. adding title, using tight layout etc. However, I tried to add title and the title doesn't show up. Any ideas why and how can I add the title using Matplotlib?

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

myBaseline=1.5
shap_values_0 = np.array([-1, -4, 3])
test_point_0 = np.array([11, 12, 13])
features_names = ['a1','a2','a3']

shap.plots.force(myBaseline,shap_values_0,test_point_0,features_names,matplotlib = 1)
plt.suptitle("This is my title")    # It doesn't show up, why?
fig = plt.gcf()
fig.canvas.draw()
plt.close()

Answer 1

The last lines in force_plot are:

if show:
    plt.show()
else:
    return plt.gcf()

so, if you set show = False you can get prepared SHAP plot as figure object and customize it to your needs as usual:

import shap

myBaseline = 1.5
shap_values_0 = np.array([-1, -4, 3])
test_point_0 = np.array([11, 12, 13])
features_names = ["a1", "a2", "a3"]

shap.plots.force(
    myBaseline, shap_values_0, test_point_0, features_names, matplotlib=True, show=False
)
plt.title("This is my title", y=1.75)
plt.show()

Answer 2

I had to add show=0 at shap.plots.force, i.e.

shap.plots.force(myBaseline,shap_values_0,test_point_0,features_names,matplotlib = 1, show=0)

I have no idea why it works, but it does.