matplotlib dynamic plotting

Hi, after computer change, matplotlib don't work dynamically.
Before, it was able to update the figure at each iteration of a loop. Today only the last data are plotted.
Configuration :
HP zBook 15 G3 with NVidia Quadro

###Bug report

Bug summary

A figure inside a loop are not updated at each step

Code for reproduction

import matplotlib.pyplot as plt
import numpy as np

x = np.arange(128)
plt.figure(1)
plt.ion()
plt.hold(False)
for it in range(5):
    plt.plot(x, x+it)
    plt.draw()

plt.ioff()
plt.show()

Expected outcome

I expect to see one plot at each step of the for loop

Matplotlib version
1.5.1

Python version
3.5.2

OS
Ubuntu 16.04 LTS

All of them had been installed from Ubuntu repository using synaptic

I think you may need to add plt.pause(0.01) after plt.draw() - can you try that?

Thank you very much Pete It works now ! It triggers an alarm, but it works : /usr/local/lib/python3.5/dist-packages/matplotlib/backend_bases.py:2437: MatplotlibDeprecationWarning: Using default event loop until function specific to this GUI is implemented warnings.warn(str, mplDeprecation) Do you know why plt.pause() allows dynamic plots ? De: "Pete Huang" <notifications@github.com> À: "matplotlib/matplotlib" <matplotlib@noreply.github.com> Cc: "pierre campistron" <pierre.campistron@univ-valenciennes.fr>, "Author" <author@noreply.github.com> Envoyé: Samedi 7 Janvier 2017 16:29:36 Objet: Re: [matplotlib/matplotlib] matplotlib dynamic plotting (#7759) I think you may need to add plt.pause(0.01) after plt.draw() - can you try that? — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub , or mute the thread .

I'm entirely the wrong person to ask for the "why", but I'm glad it works! I just shuttled around StackOverflow for the answer :)

'why' is a bit of a long question (see #4779 for an old PR trying to document all of the details). In very short, we made many of the GUI embedding more asynchronous, that is calling plt.draw calls fig.canvas.draw_idle() which asks the GUI to re-render the figure. If you never turn control over to the GUI event loop to process it's events, then it does not have a chance to update it's self (you will also note that while your code is running you can not pan/zoom the figure).

Doing

import matplotlib.pyplot as plt
plt.ion()
import numpy as np

x = np.arange(128)
fig, ax = plt.subplots()

for it in range(5):
    ax.plot(x, x+it)
    # fig.canvas.draw_idle()  # required to work on mpl < 1.5
    fig.canvas.flush_events()
    time.sleep(1)

plt.ioff()
plt.show()

should do what you want.

Thank you very much Thomas It works perfectly, and I can zoom on figure during the loop ! I understand a little better now ;) Best regards Pierre De: "Thomas A Caswell" <notifications@github.com> À: "matplotlib/matplotlib" <matplotlib@noreply.github.com> Cc: "pierre campistron" <pierre.campistron@univ-valenciennes.fr>, "Author" <author@noreply.github.com> Envoyé: Samedi 7 Janvier 2017 22:07:19 Objet: Re: [matplotlib/matplotlib] matplotlib dynamic plotting (#7759) 'why' is a bit of a long question (see #4779 for an old PR trying to document all of the details). In very short, we made many of the GUI embedding more asynchronous, that is calling plt.draw calls fig.canvas.draw_idle() which asks the GUI to re-render the figure. If you never turn control over to the GUI event loop to process it's events, then it does not have a chance to update it's self (you will also note that while your code is running you can not pan/zoom the figure). Doing import matplotlib.pyplot as plt plt.ion() import numpy as np x = np.arange( 128 ) fig, ax = plt.subplots() for it in range ( 5 ): ax.plot(x, x + it) # fig.canvas.draw_idle() # required to work on mpl < 1.5 fig.canvas.flush_events() time.sleep( 1 ) plt.ioff() plt.show() should do what you want. — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub , or mute the thread .

👍

Should we close this?

Yes, I think that the problem is solved. Many thanks for all you De: "Pete Huang" <notifications@github.com> À: "matplotlib/matplotlib" <matplotlib@noreply.github.com> Cc: "pierre campistron" <pierre.campistron@univ-valenciennes.fr>, "Author" <author@noreply.github.com> Envoyé: Dimanche 8 Janvier 2017 17:40:22 Objet: Re: [matplotlib/matplotlib] matplotlib dynamic plotting (#7759) 👍 Should we close this? — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub , or mute the thread .

Hey guys, any idea on how to fix my equivalent MatplotlibDeprecationWarning. I realized I essentially have the exact same problem except on a larger scale?

I have set up a server that will read in live data and produce two 3d plots. You can run this simulated code below (instead of reading in the data from the client).

import matplotlib.pyplot as plt
from threading import Thread, Lock, Condition
import random, time, socket
from mpl_toolkits.mplot3d import Axes3D
import numpy as np


class Plotter:
    def __init__(self):

        # temp list of data received by server
        self.data = [[] for i in range(3)]

        # threading variables
        self.mutex = Lock()
        self.points_received = 0
        self.cv = Condition()

        # initialize figure
        self.fig = plt.figure()
        self.run_plot = False
        self.ax = self.fig.add_subplot(111, projection='3d')
        self.ax.set_xlim(0, 1)
        self.ax.set_ylim(0, 1)
        self.ax.set_zlim(0, 1)
        plt.ion()
        plt.show()

    # This just simulates reading from a socket.
    def data_listener(self):
        while True:
            time.sleep(1)
            with self.mutex:
                new_data = [random.random() for i in range(3)]

                # append new data to be plotted and check max/min to update axes limits
                for axis in range(3):
                    self.data[axis].append(new_data[axis])

    def sub_plot(self):
        # wait until ready, <Enter> is pressed
        self.cv.acquire()
        while not self.run_plot:
            self.cv.wait()  # I think this causes the plot to not respond before hitting <Enter>
        self.cv.release()

        while self.run_plot:
            time.sleep(0.01)
            with self.mutex:
                try:
                    # add data and clear graph
                    self.ax.scatter(self.data[0], self.data[1], self.data[2])
                    self.data = [[] for i in range(3)]

                    plt.pause(0.000001)
                    # self.fig.canvas.flush_events()
                except:
                    print ("error")

    def cmdline_input(self):
        # Start then End Plot
        for status in ["start", "end"]:
            text_start = raw_input("Hit <Enter> to " + status + " plotting")
            while text_start != "":
                print "Wrong input"
                text_start = raw_input("Hit <Enter> to " + status + " plotting")

            self.cv.acquire()
            if status == "start":
                self.run_plot = True
            elif status == "end":
                self.run_plot = False
            self.cv.notify()
            self.cv.release()

    def run(self):
        d = Thread(target=self.data_listener)
        d.start()

        # start cmdline input
        c_start = Thread(target=self.cmdline_input)
        c_start.start()

        # subplot
        self.sub_plot()


if __name__ == '__main__':
    p = Plotter()
    p.run()

You guys have a better handle on how to fix this issue. Currently when I run the live plot (randomly sending over numbers), I can change the viewing angle with my cursor but I can't zoom in or out. I tried adding in self.fig.canvas.flush_events() after plt.pause(0.000001) but that didn't seem to functionally change anything.

I also noticed that when my plot isn't receiving live data, the window is unresponsive. I.e. If you try to maximize the window or change the window size the whole screen gets blurred. I have a feeling that this has something to do with me putting the plotting thread to sleep but maybe there's a simple fix?

This question is probably better sent to the mailing list (matplotlib-users@python.org ; you will have to subscribe to post).

#4779 may also be informative reading.

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petehuang commented on Jan 7, 2017

MpCamp commented on Jan 7, 2017

petehuang commented on Jan 7, 2017

tacaswell commented on Jan 7, 2017

MpCamp commented on Jan 8, 2017

petehuang commented on Jan 8, 2017

MpCamp commented on Jan 8, 2017

maxgittelman commented on Oct 25, 2017

tacaswell commented on Oct 26, 2017

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