问题
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>
回答1:
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()
来源：https://stackoverflow.com/questions/41459657/how-to-create-dynamic-plots-to-display-on-flask