python - Matplotlib - 强制绘图显示然后返回主代码

Question

这是我所追求的 MWE，改编自 this question :

from matplotlib.pyplot import plot, draw, show

def make_plot():
    plot([1,2,3])
    draw()
    print 'continue computation'

print('Do something before plotting.')
# Now display plot in a window
make_plot()

answer = raw_input('Back to main and window visible? ')
if answer == 'y':
    print('Excellent')
else:
    print('Nope')

show()

我想要的是:我调用函数来制作绘图，出现绘图窗口，然后我可以返回到提示符，以便我可以输入一些值(基于刚刚显示的图像)并继续使用代码(然后窗口可以关闭或保留在那里，我不在乎)。

相反，我得到的是带有绘图的窗口仅在代码完成后出现，这不好。

---

添加 1

我尝试了以下相同的结果，绘图窗口出现在代码的末尾而不是之前:

from matplotlib.pyplot import plot, ion, draw

ion() # enables interactive mode
plot([1,2,3]) # result shows immediately (implicit draw())
# at the end call show to ensure window won't close.
draw()

answer = raw_input('Back to main and window visible? ')
if answer == 'y':
    print('Excellent')
else:
    print('Nope')

如果我将 draw() 更改为 show()，也会发生同样的情况。

---

添加 2

我尝试了以下方法:

from multiprocessing import Process
from matplotlib.pyplot import plot, show

def plot_graph(*args):
    for data in args:
        plot(data)
    show()

p = Process(target=plot_graph, args=([1, 2, 3],))
p.start()

print 'computation continues...'

print 'Now lets wait for the graph be closed to continue...:'
p.join()

这会导致 Canopy 中出现 Python kernel has crashed 错误，并显示以下消息:

The kernel (user Python environment) has terminated with error code -6. This may be due to a bug in your code or in the kernel itself.

Output captured from the kernel process is shown below.

[IPKernelApp] To connect another client to this kernel, use:
[IPKernelApp] --existing /tmp/tmp9cshhw.json
QGtkStyle could not resolve GTK. Make sure you have installed the proper libraries.
[xcb] Unknown sequence number while processing queue
[xcb] Most likely this is a multi-threaded client and XInitThreads has not been called
[xcb] Aborting, sorry about that.
python: ../../src/xcb_io.c:274: poll_for_event: La declaración `!xcb_xlib_threads_sequence_lost' no se cumple.

我应该提到我在基于 Ubuntu 12.04 的 elementary OS 中运行 Canopy。

---

添加 3

还尝试了 this question 中发布的解决方案:

import numpy
from matplotlib import pyplot as plt

if __name__ == '__main__':
    x = [1, 2, 3]
    plt.ion() # turn on interactive mode
    for loop in range(0,3):
        y = numpy.dot(x, loop)
        plt.figure()
        plt.plot(x,y)
        plt.show()
        _ = raw_input("Press [enter] to continue.")

这会随着代码的推进(即:用户点击 [enter])显示空白的绘图窗口，并且仅在代码完成后显示图像。

这个解决方案(也在同一个问题中)甚至不显示绘图窗口:

import numpy
from matplotlib import pyplot as plt
if __name__ == '__main__':
    x = [1, 2, 3]
    plt.ion() # turn on interactive mode, non-blocking `show`
    for loop in range(0,3):
        y = numpy.dot(x, loop)
        plt.figure()   # create a new figure
        plt.plot(x,y)  # plot the figure
        plt.show()     # show the figure, non-blocking
        _ = raw_input("Press [enter] to continue.") # wait for input from the user
        plt.close()    # close the figure to show the next one.

Answer 1

你可以使用plt.show(block=False)，直接解除阻塞。

对于你的例子，这可能是

from matplotlib.pyplot import plot, show

def make_plot():
    plot([1,2,3])
    show(block=False)
    print('continue computation')

print('Do something before plotting.')
# Now display plot in a window
make_plot()

answer = input('Back to main and window visible? ')
if answer == 'y':
    print('Excellent')
else:
    print('Nope')