[Bug]: Funcanimation has some problem with vscode

[dentistfrankchen]

Bug summary

THIS IS NOT A POST FOR COMMUNITY HELP.

THIS IS A BUG REPORT.

PLEASE DO NOT CLOSE BEFORE REPLICATION.

Code for reproduction

%matplotlib ipympl

import numpy as np
import matplotlib.pyplot as plt
import matplotlib.animation as animation
import time

fig, ax = plt.subplots()

XX=[1,2,3]
YY=[2,4,6]
line, = ax.plot(XX,YY)

ax.set_xlim(-2,100)
ax.set_ylim(-2,100)

num=0

def init():
    line.set_ydata(YY)
    line.set_xdata(XX)
    return line,

def animate(i):
    ii=0
    while ii!=3:
        XX[ii]+=1
        ii+=1

    '''for ii in XX:
        ii+=1'''
    line.set_ydata(YY)
    line.set_xdata(XX)
    return line,

ani = animation.FuncAnimation(
    fig, animate,init_func=init,interval=50, blit=True, save_count=50) #interval is millisecond

plt.show()

Actual outcome

the pic do not move.

Expected outcome

the pic should move.

Additional information

use while instead of for can solve this problem.

Operating system

windows 10

Matplotlib Version

3.5.1

Matplotlib Backend

ipympl

Python version

3.8.1

Jupyter version

3.0.16

Installation

pip

[dentistfrankchen]

Now the code runs well. However if you use the for loop i quoted, the bug will appear.

[dentistfrankchen]

In general, the while loop is working well, however the for loop is not.

[WeatherGod]

In the for-loop version, you are doing `ii+=1`. This does *not* update the `XX` list in-place. Integers and floats are immutable in python, so doing this only creates a new integer or float and assigns it to the variable, completely losing its connection to the `XX` list. The same would happen if `XX` was a numpy array. In the while loop, the line is `XX[ii] += 1`, which will make a new integer or float, but then explicitly assigns it back into the `XX` list. I hope that clears it up for you.

…

On Tue, Dec 14, 2021 at 8:34 AM dentistfrankchen ***@***.***> wrote: In general, the while loop is working well, however the for loop is not. — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#21951 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AACHF6CIBFLSPLGU5K4HDX3UQ5BXDANCNFSM5KA4YPQQ> . Triage notifications on the go with GitHub Mobile for iOS <https://apps.apple.com/app/apple-store/id1477376905?ct=notification-email&mt=8&pt=524675> or Android <https://play.google.com/store/apps/details?id=com.github.android&referrer=utm_campaign%3Dnotification-email%26utm_medium%3Demail%26utm_source%3Dgithub>.

[jklymak]

@dentistfrankchen this is not a general help with python forum. Again please post to https://discourse.matplotlib.org and do not open duplicate reports.

[WeatherGod]

Agreed that is the better place to have handled this. And while discussing the problem there, if it was discovered to be a bug with matplotlib, we would have then opened a bug report here.

…

On Tue, Dec 14, 2021 at 8:59 AM Jody Klymak ***@***.***> wrote: @dentistfrankchen <https://github.com/dentistfrankchen> this is not a general help with python forum. Again please post to https://discourse.matplotlib.org and do not open duplicate reports. — You are receiving this because you commented. Reply to this email directly, view it on GitHub <#21951 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AACHF6HM4XBIT3DRYEPNHVDUQ5EVPANCNFSM5KA4YPQQ> . Triage notifications on the go with GitHub Mobile for iOS <https://apps.apple.com/app/apple-store/id1477376905?ct=notification-email&mt=8&pt=524675> or Android <https://play.google.com/store/apps/details?id=com.github.android&referrer=utm_campaign%3Dnotification-email%26utm_medium%3Demail%26utm_source%3Dgithub>.

[dentistfrankchen]

Thanks for your reply. This helps me a lot. Frank Chen ***@***.*** 签名由 网易邮箱大师 定制 On 12/14/2021 21:49, Benjamin Root wrote: In the for-loop version, you are doing `ii+=1`. This does *not* update the `XX` list in-place. Integers and floats are immutable in python, so doing this only creates a new integer or float and assigns it to the variable, completely losing its connection to the `XX` list. The same would happen if `XX` was a numpy array. In the while loop, the line is `XX[ii] += 1`, which will make a new integer or float, but then explicitly assigns it back into the `XX` list. I hope that clears it up for you. On Tue, Dec 14, 2021 at 8:34 AM dentistfrankchen ***@***.***> wrote: > In general, the while loop is working well, however the for loop is not. > > — > You are receiving this because you are subscribed to this thread. > Reply to this email directly, view it on GitHub > <#21951 (comment)>, > or unsubscribe > <https://github.com/notifications/unsubscribe-auth/AACHF6CIBFLSPLGU5K4HDX3UQ5BXDANCNFSM5KA4YPQQ> > . > Triage notifications on the go with GitHub Mobile for iOS > <https://apps.apple.com/app/apple-store/id1477376905?ct=notification-email&mt=8&pt=524675> > or Android > <https://play.google.com/store/apps/details?id=com.github.android&referrer=utm_campaign%3Dnotification-email%26utm_medium%3Demail%26utm_source%3Dgithub>. > > — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub, or unsubscribe. Triage notifications on the go with GitHub Mobile for iOS or Android.