Matplotlib support for `put_image`?

[tirthajyoti]

Can you integrate Matplotlib support for put_image() function i.e. somehow it can accept a Matplotlib figure object and render it nicely? This will open up a range of data science applications.

I know you have Bokeh and Plotly integration but a lot of users are more comfortable with Matplotlib than Bokeh or Plotly.

[tirthajyoti]

Actually, I created a simple demo for Matplotlib plots. Here is the code, you can use it in your demo examples.

You may find the function fig2img particularly interesting as it converts a Matplotlib figure object to a PIL.Image.image object.

from pywebio.input import *
from pywebio.output import *
from pywebio import start_server
import matplotlib.pyplot as plt
import numpy as np
from PIL import Image
import io

def data_gen(num=100):
    """
    Generates random samples for plotting
    """
    a = np.random.normal(size=num)
    return a

def plot_raw(a):
    """
    Plots line graph
    """
    plt.close()
    plt.figure(figsize=(12,5))
    plt.plot(a)
    return plt.gcf()

def plot_hist(a):
    """
    Plots histogram
    """
    plt.close()
    plt.figure(figsize=(12,5))
    plt.hist(a,color='orange',edgecolor='k')
    return plt.gcf()

def fig2img(fig):
    """
    Convert a Matplotlib figure to a PIL Image and return it
    """
    buf = io.BytesIO()
    fig.savefig(buf)
    buf.seek(0)
    img = Image.open(buf)
    return img
    
def Generate(num=100):
    """
    Generates plot, called from the `Generate` button 
    """
    remove(scope='raw')
    with use_scope(name='raw',clear=True,) as img:
        a = data_gen(num)
        f1 = plot_raw(a)
        im1 = fig2img(f1)
        put_image(im1)
        f2 = plot_hist(a)
        im2 = fig2img(f2)
        put_image(im2)
    
def app():
        
    put_markdown("""
    # Matplotlib plot demo
    
    We show two plots from random gaussian samples
    
    - A line plot
    - A histogram
    """, strip_indent=4)
    
    num_samples = input("Number of samples", type=NUMBER)
    Generate(num_samples)
    
if __name__ == '__main__':
    start_server(app,port=9999,debug=True)

[wang0618]

A more simple version is of fig2img() is:

def fig2img(fig):
    """
    Convert a Matplotlib figure to a bytes and return it
    """
    buf = io.BytesIO()
    fig.savefig(buf)
    return buf.getvalue()