flask_matplotlib_demo.py

import flask

app = flask.Flask(__name__)

@app.route('/')
def index():
    return 'ahoj <img src="/graf">'

@app.route('/graf')
def graf():
    import numpy as np
    import matplotlib.pyplot as plt
    import matplotlib.lines as lines

    fig = plt.figure()

    # nejaky matplotlib example
    l1 = lines.Line2D([0, 1], [0, 1], transform=fig.transFigure, figure=fig)
    l2 = lines.Line2D([0, 1], [1, 0], transform=fig.transFigure, figure=fig)
    fig.lines.extend([l1, l2])

    #plt.show()

    import io
    buf = io.BytesIO()
    plt.savefig(buf, format='png')
    buf.seek(0)

    return flask.send_file(buf, mimetype='image/png')

app.run(debug=True)