Idea: Connection to matplotlib over BytesIO

Note: This is only an idea, and should not have high priority. Related to #363

It would be really cool to have manim smoothly interact with matplotlib. Therefore one idea: Do you think it is possible, to save figures created in matplotlib to a byte stream, which is then read by ImageMobject? Then there is no reading and writing to the disk in between. One ide based on the idea of https://mellowd.dev/python/using-io-bytesio/, I tried the following:

from manim import *
import matplotlib.pyplot as plt
import io


class ConnectingMatplotlib(Scene):
    def construct(self):
        t = np.arange(0.0, 2.0, 0.01)
        s = 1 + np.sin(2 * np.pi * t)
        fig, ax = plt.subplots()
        ax.plot(t, s)
        ax.set(xlabel='time (s)', ylabel='voltage (mV)',
               title='About as simple as it gets')
        ax.grid()

        b = io.BytesIO()
        plt.savefig(b, format='png')
        img = ImageMobject(b.read())  ## error: IndexError: tuple index out of range
        self.add(img)

But reading the byte stream is not possible just like that. Do you think this is something, that can be easily solved?

[kolibril13]

@behackl : Wow,thank you so much! I’m speechless and happy! With saving and loading from disk (my method): — 35.34524869918823 seconds — With your method: — 6.816277742385864 seconds — And here is a script:

from manim import *
import matplotlib.pyplot as plt


def my_function(amplitude, x):
    return amplitude * np.sin(x)


def get_image_plot(amplitude, x):
    fig, ax = plt.subplots()
    ax.plot(x, my_function(amplitude, x))
    plt.ylim(-1, 1)
    ax.set(xlabel='distance (x)', ylabel='amplitude',
           title='My animated plot')
    fig.canvas.draw()
    img = ImageMobject(fig.canvas.buffer_rgba()).scale(4.5)
    plt.close(fig)
    return img


class ConnectingMatplotlib(Scene):
    def construct(self):
        x_values = np.linspace(0, 30, 400)
        amp1 = 0.5
        amp2 = 1
        tr_amplitude = ValueTracker(amp1)
        image = get_image_plot(amp1, x_values)
        self.add(image)

        def update_image(mob):
            new_mob = get_image_plot(tr_amplitude.get_value(), x_values)
            mob.become(new_mob)

        image.add_updater(update_image)

        self.play(tr_amplitude.set_value, amp2, run_time=3)

import time
from pathlib import Path

if __name__ == "__main__":
    script = f"{Path(__file__).resolve()}"
    start_time = time.time()

    os.system( f"manim  -l --custom_folders  --disable_caching  -p -c 'BLACK" + script)
    print("--- %s seconds ---" % (time.time() - start_time))

[behackl]

For me, running the code from https://mellowd.dev/python/using-io-bytesio/ always leads to an empty image. I think that before accessing the byte stream, something like b.seek(0) has to be called.

Anyhow, matplotlib also allows to get the rendered figure in a format suitable for ImageMobject by calling buffer_rgba() of the corresponding canvas:

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

from manim import Scene, ImageMobject

class ConnectingMatplotlib(Scene):
    def construct(self):        
        t = np.arange(0.0, 2.0, 0.01)
        s = 1 + np.sin(2 * np.pi * t)

        fig, ax = plt.subplots()
        ax.plot(t, s)

        ax.set(xlabel='time (s)', ylabel='voltage (mV)',
               title='About as simple as it gets')
        ax.grid()
        
        fig.canvas.draw()
        img = ImageMobject(fig.canvas.buffer_rgba())

        self.add(img)
        self.wait()