Python Matplotlib barchart updating color interactively

Question

I am trying to understand interactive plots in matplotlib (in Jupyter Notebook).

Here is a piece of codes and I would like to know why this is not working.

import matplotlib.pyplot as plt
%matplotlib notebook

fig, ax = plt.subplots()

BarChart = ax.bar(df.index, df.mean(axis=1), color = 'black')

def on_click(event):
    for Bar in BarChart:
        Bar.set_color(color='red')

fig.canvas.mpl_connect('button_press_event', on_click)

plt.show()

Could anybody explain me why this is not updating the color of bars into red and how to fix it?

When the for loop is used in a static case, ie without the on_click and mpl_connect function, it does update the bar colors in the original plot.

I was wondering if I need an expression to explicitly updating the plot.

Answer 1

Bar is a Rectangle patch, therefore you can use set_color to change the color of the bars. However, it does not accept color as a keyword argument. From the docs, the argument you need to use is c

Therefore, you can either remove color= , or replace it with c=

import matplotlib.pyplot as plt
%matplotlib notebook

fig, ax = plt.subplots()

BarChart = ax.bar(df.index, df.mean(axis=1), color = 'black')

def on_click(event):
    for Bar in BarChart:
        Bar.set_color('red')
        # Bar.set_color(c='red')  # this also works

fig.canvas.mpl_connect('button_press_event', on_click)

plt.show()