Matplotlib support for put_image? #89

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1. tirthajyoti

   added

   bugSomething isn't workingSomething isn't working

   on May 7, 2021
2. tirthajyoti commented on May 7, 2021

   

   tirthajyoti

   on May 7, 2021

   Author

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   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)

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3. wang0618 commented on May 8, 2021

   

   wang0618

   on May 8, 2021

   Member

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   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()

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4. pywebio

   locked and limited conversation to collaborators on Dec 18, 2021
5. wang0618

   converted this issue into a discussion #238 on Dec 18, 2021