Displaying matplotlib plot using Flask

Question

I want to visualize the plot (SciView) in my Flask web project.

Here is my code:

import matplotlib.pyplot as plt 
# x-coordinates of left sides of bars 
left = [1, 2, 3, 4, 5] 
# heights of bars 
height = [10, 24, 36, 40, 5] 
# labels for bars 
tick_label = ['one', 'two', 'three', 'four', 'five'] 
# plotting a bar chart 
plt.bar(left, height, tick_label=tick_label, width=0.8, color=['red', 'green']) 
# naming the y-axis 
plt.xlabel('y - axis') 
# naming the x-axis 
plt.xlabel('x - axis') 
# plot title 
plt.title('My bar chart!') 
# function to show the plot 
plt.show()

I've tried running this code in my Flask project, but there is no output.

Answer 1

A possible solution is to save the figure with plt.savefig and attach it to an HTML <img> tag.

from flask import Flask, render_template
import matplotlib.pyplot as plt

app = Flask(__name__)

@app.route('/plot')
def plot():
    left = [1, 2, 3, 4, 5]
    # heights of bars
    height = [10, 24, 36, 40, 5]
    # labels for bars
    tick_label = ['one', 'two', 'three', 'four', 'five']
    # plotting a bar chart
    plt.bar(left, height, tick_label=tick_label, width=0.8, color=['red', 'green'])

    # naming the y-axis
    plt.ylabel('y - axis')
    # naming the x-axis
    plt.xlabel('x - axis')
    # plot title
    plt.title('My bar chart!')

    plt.savefig('static/images/plot.png')

    return render_template('plot.html', url='/static/images/plot.png')

if __name__ == '__main__':
   app.run()

Then on templates/plot.html

<img src={{url}} alt="Chart" height="auto" width="100%">