# -*- noplot -*-
# Demo of using multiprocessing for generating data in one process and plotting
# in another.
# Written by Robert Cimrman

from __future__ import print_function
import time
from multiprocessing import Process, Pipe
import numpy as np

import matplotlib
matplotlib.use('GtkAgg')
import matplotlib.pyplot as plt
import gobject


class ProcessPlotter(object):
    def __init__(self):
        self.x = []
        self.y = []

    def terminate(self):
        plt.close('all')

    def poll_draw(self):

        def call_back():
            while 1:
                if not self.pipe.poll():
                    break

                command = self.pipe.recv()

                if command is None:
                    self.terminate()
                    return False

                else:
                    self.x.append(command[0])
                    self.y.append(command[1])
                    self.ax.plot(self.x, self.y, 'ro')

            self.fig.canvas.draw()
            return True

        return call_back

    def __call__(self, pipe):
        print('starting plotter...')

        self.pipe = pipe
        self.fig, self.ax = plt.subplots()
        self.gid = gobject.timeout_add(1000, self.poll_draw())

        print('...done')
        plt.show()


class NBPlot(object):
    def __init__(self):
        self.plot_pipe, plotter_pipe = Pipe()
        self.plotter = ProcessPlotter()
        self.plot_process = Process(target=self.plotter,
                                    args=(plotter_pipe,))
        self.plot_process.daemon = True
        self.plot_process.start()

    def plot(self, finished=False):
        send = self.plot_pipe.send
        if finished:
            send(None)
        else:
            data = np.random.random(2)
            send(data)


def main():
    pl = NBPlot()
    for ii in range(10):
        pl.plot()
        time.sleep(0.5)
    try:
        input = raw_input
    except NameError:
        pass
    input('press Enter...')
    pl.plot(finished=True)

if __name__ == '__main__':
    main() 

$ py multiprocess.py
Traceback (most recent call last):
  File "multiprocess.py", line 12, in 
  matplotlib.use('GtkAgg')
  File "/opt/rh/rh-python36/root/usr/lib64/python3.6/site-packages/matplotlib/__init__.py",
  line 1349, in use name = validate_backend(arg)
  File "/opt/rh/rh-python36/root/usr/lib64/python3.6/site-packages/matplotlib/rcsetup.py",
  line 252, in validate_backend else _validate_standard_backends(s))
  File "/opt/rh/rh-python36/root/usr/lib64/python3.6/site-packages/matplotlib/rcsetup.py",
  line 65, in __call__ % (self.key, s, list(self.valid.values())))
ValueError: Unrecognized backend string 'gtkagg': valid strings are ['GTK3Agg', 'GTK3Cairo',
'MacOSX', 'nbAgg', 'Qt4Agg', 'Qt4Cairo', 'Qt5Agg', 'Qt5Cairo', 'TkAgg', 'TkCairo', 'WebAgg',
'WX', 'WXAgg', 'WXCairo', 'agg', 'cairo', 'pdf', 'pgf', 'ps', 'svg', 'template'] 

Traceback (most recent call last):
  File "M:\______\multiprocess.py", line 12, in 
    matplotlib.use('GtkAgg')
  File "C:\Users\______\AppData\Local\Programs\Python
    \Python311\Lib\site-packages\matplotlib\__init__.py", line 1234, in use
    name = validate_backend(backend)
           ^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\______\AppData\Local\Programs\Python
    \Python311\Lib\site-packages\matplotlib\rcsetup.py", line 252, in validate_backend
    else _validate_standard_backends(s))
         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\______\AppData\Local\Programs\Python
    \Python311\Lib\site-packages\matplotlib\rcsetup.py", line 82, in __call__
    raise ValueError(msg)
ValueError: 'gtkagg' is not a valid value for backend; supported values are 
  ['GTK3Agg', 'GTK3Cairo', 'GTK4Agg', 'GTK4Cairo', 'MacOSX', 'nbAgg', 'QtAgg', 'QtCairo', 
   'Qt5Agg', 'Qt5Cairo', 'TkAgg', 'TkCairo', 'WebAgg', 'WX', 'WXAgg', 'WXCairo', 'agg', 
   'cairo', 'pdf', 'pgf', 'ps', 'svg', 'template'] 

Traceback (most recent call last):
  File "E:\______\multiprocess.py", line 12, in 
    matplotlib.use('GtkAgg')
  File "C:\Program Files\Python312\Lib\site-packages\matplotlib\__init__.py", 
    line 1246, in use
    name = validate_backend(backend)
           ^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Program Files\Python312\Lib\site-packages\matplotlib\rcsetup.py", 
    line 252, in validate_backend
    else _validate_standard_backends(s))
         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Program Files\Python312\Lib\site-packages\matplotlib\rcsetup.py", 
    line 82, in __call__
    raise ValueError(msg)
ValueError: 'gtkagg' is not a valid value for backend; supported values are 
  ['GTK3Agg', 'GTK3Cairo', 'GTK4Agg', 'GTK4Cairo', 'MacOSX', 'nbAgg', 'QtAgg', 
   'QtCairo', 'Qt5Agg', 'Qt5Cairo', 'TkAgg', 'TkCairo', 'WebAgg', 'WX', 'WXAgg', 
   'WXCairo', 'agg', 'cairo', 'pdf', 'pgf', 'ps', 'svg', 'template'] 

"""
===============
Multiprocessing
===============

Demo of using multiprocessing for generating data in one process and
plotting in another.

Written by Robert Cimrman
"""

import multiprocessing as mp
import time

import matplotlib.pyplot as plt
import numpy as np

# Fixing random state for reproducibility
np.random.seed(19680801)

# %%
#
# Processing Class
# ================
#
# This class plots data it receives from a pipe.
#


class ProcessPlotter:
    def __init__(self):
        self.x = []
        self.y = []

    def terminate(self):
        plt.close('all')

    def call_back(self):
        while self.pipe.poll():
            command = self.pipe.recv()
            if command is None:
                self.terminate()
                return False
            else:
                self.x.append(command[0])
                self.y.append(command[1])
                self.ax.plot(self.x, self.y, 'ro')
        self.fig.canvas.draw()
        return True

    def __call__(self, pipe):
        print('starting plotter...')

        self.pipe = pipe
        self.fig, self.ax = plt.subplots()
        timer = self.fig.canvas.new_timer(interval=1000)
        timer.add_callback(self.call_back)
        timer.start()

        print('...done')
        plt.show()

# %%
#
# Plotting class
# ==============
#
# This class uses multiprocessing to spawn a process to run code from the
# class above. When initialized, it creates a pipe and an instance of
# ``ProcessPlotter`` which will be run in a separate process.
#
# When run from the command line, the parent process sends data to the spawned
# process which is then plotted via the callback function specified in
# ``ProcessPlotter:__call__``.
#


class NBPlot:
    def __init__(self):
        self.plot_pipe, plotter_pipe = mp.Pipe()
        self.plotter = ProcessPlotter()
        self.plot_process = mp.Process(
            target=self.plotter, args=(plotter_pipe,), daemon=True)
        self.plot_process.start()

    def plot(self, finished=False):
        send = self.plot_pipe.send
        if finished:
            send(None)
        else:
            data = np.random.random(2)
            send(data)


def main():
    pl = NBPlot()
    for _ in range(10):
        pl.plot()
        time.sleep(0.5)
    pl.plot(finished=True)


if __name__ == '__main__':
    if plt.get_backend() == "MacOSX":
        mp.set_start_method("forkserver")
    main() 

　Python 3.11.6 (matplotlib 3.7.1) 及び Python 3.12.0 (matplotlib 3.8.1) 共に、正常実行です。

　

　

　

• 2023/11/17 Ver=1.04 Python 3.12.0 (matplotlib 3.8.1)で確認
• 2023/11/17 Ver=1.04 Python 3.11.6 (matplotlib 3.7.1)で確認
• 2023/03/30 Ver=1.03 Python 3.11.2 で確認
• 2020/10/30 Ver=1.01 Python 3.7.8 で確認
• 2018/11/25 Ver=1.01 初版リリース

Top