Passing a matplotlib figure to HTML (flask)

Question

I am using matplotlib to render some figure in a web app. I\'ve used fig.savefig() before when I\'m just running scripts. However, I need a function to return a

Answer 1

Python 3

I went through a lot of trouble with errors like - Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'NSWindow drag regions should only be invalidated on the Main Thread!

For all those who want to use matplotlib with flask and render the graph on an html page in python 3, here you go -

In the __init__.py

import matplotlib
matplotlib.use('Agg')
import matplotlib.pyplot as plt
from flask import Flask, render_template
from io import BytesIO
import base64

    @app.route('/plot')
    def plot():
        img = BytesIO()
        y = [1,2,3,4,5]
        x = [0,2,1,3,4]

        plt.plot(x,y)

        plt.savefig(img, format='png')
        plt.close()
        img.seek(0)
        plot_url = base64.b64encode(img.getvalue()).decode('utf8')

        return render_template('plot.html', plot_url=plot_url)

In flaskr/templates/plot.html

  
Heatmap