Matplotlib remove line on click

Question

I'm trying to write something that lets me remove lines by clicking on a matplotlib plot. I'll later try deleting the lines by clicking on them.

For now, I've simplified the code as much as I can, but I still can't figure it out. Both lines remain on the plot, and if I click twice, I get the message:

"ValueError: list.remove(x): x not in list".

The remove command works if I put it outside of onclick(event), and print statements work when I put them inside of onclick(event).

But I can't get any farther than that. I've also tried clearing the entire plot with plt.gca(), but that doesn't seem to do anything.

Clearly something basic I don't understand, so I was hoping someone could clarify what I'm doing wrong.

import matplotlib.pyplot as plt
import numpy as np
    
xdata = np.arange(0,20,1)
ydata1 = np.arange(0,40,2)
ydata2 = np.arange(0,80,4)
    
fig,ax = plt.subplots()
line1, = ax.plot(xdata, ydata1)
line2, = ax.plot(xdata, ydata2)
          
def onclick(event):
    line1.remove()   #error on second click
    
plt.gcf().canvas.mpl_connect('button_press_event', onclick)

Can you try including plt.draw() in your onclick() function to redraw the figure? https://matplotlib.org/3.1.1/api/_as_gen/matplotlib.pyplot.draw.html — robbo
– robbo, Commented Jan 31, 2021 at 12:39

Idris Yalaletdinov · Accepted Answer · 2021-01-31 13:51:27Z

2

If you need to just delete lines and you don't care about the order. You can use this:

def onclick(event):

    plt.gca().lines[-1].remove()

If you require to delete a specific line:

fig,ax = plt.subplots()
line1, = ax.plot(xdata, ydata1, picker=5)
line2, = ax.plot(xdata, ydata2, picker=5)
          
def onclick(event):
    thisline = event.artist
    thisline.remove()
    
plt.gcf().canvas.mpl_connect('pick_event', onclick)

You can read more about it: https://matplotlib.org/3.1.1/gallery/event_handling/pick_event_demo.html

answered Jan 31, 2021 at 13:51

Idris Yalaletdinov

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1 Comment

Matt Over a year ago

I was not able to get either of these code samples to work, but thank you for the link. I will read that and see if I can understand it better.

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