Menu
I wish to create dynamic plots based on user input on a flask app. However I am getting the following error: string argument expected, got 'bytes'
If I use io.BytesIO(), I am not getting this error, but I am not getting the plot on test.html
from flask import Flask
from flask import render_template
import matplotlib.pyplot as plt
import io
import base64
app = Flask(__name__)
@app.route('/plot')
def build_plot():
img = io.StringIO()
y = [1,2,3,4,5]
x = [0,2,1,3,4]
plt.plot(x,y)
plt.savefig(img, format='png')
img.seek(0)
plot_url = base64.b64encode(img.getvalue())
return render_template('test.html', plot_url=plot_url)
if __name__ == '__main__':
app.debug = True
app.run()
Test.html
<!DOCTYPE html>
<html>
<title> Plot</title>
<body>
<img src="data:image/png;base64, {{ plot_url }}">
</body>
</html>
474
Make a list of data points and colors. Plot the bars with data and colors, using bar() method. Using FuncAnimation() class, make an animation by repeatedly calling a function, animation, that sets the height of the bar and facecolor of the bars. To display the figure, use show() method.
Flask automatically creates a static view that serves static files from a folder named static in your application's directory. You can also use the url_for() method to allow for more dynamic URLs. Its use reduces the amount of modification needed in the code if something needs to change in your URL references.
Use BytesIO and later decode()
Working example
from flask import Flask
#from flask import render_template
import matplotlib.pyplot as plt
import io
import base64
app = Flask(__name__)
@app.route('/plot')
def build_plot():
img = io.BytesIO()
y = [1,2,3,4,5]
x = [0,2,1,3,4]
plt.plot(x,y)
plt.savefig(img, format='png')
img.seek(0)
plot_url = base64.b64encode(img.getvalue()).decode()
return '<img src="data:image/png;base64,{}">'.format(plot_url)
if __name__ == '__main__':
app.debug = True
app.run()
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With
