Created
April 20, 2013 14:43
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Serving dynamic images with Pandas and matplotlib (using flask)
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| #!/usr/bin/env python2 | |
| '''Serving dynamic images with Pandas and matplotlib (using flask).''' | |
| import matplotlib | |
| matplotlib.use('Agg') | |
| import matplotlib.pyplot as plt | |
| import numpy as np | |
| import pandas as pd | |
| from cStringIO import StringIO | |
| import base64 | |
| from flask import Flask | |
| app = Flask(__name__) | |
| html = ''' | |
| <html> | |
| <body> | |
| <img src="data:image/png;base64,{}" /> | |
| </body> | |
| </html> | |
| ''' | |
| @app.route("/") | |
| def hello(): | |
| df = pd.DataFrame( | |
| {'y':np.random.randn(10), 'z':np.random.randn(10)}, | |
| index=pd.period_range('1-2000',periods=10), | |
| ) | |
| fig = plt.figure() | |
| ax = fig.add_subplot(1, 1, 1) | |
| df.plot(ax=ax) | |
| io = StringIO() | |
| fig.savefig(io, format='png') | |
| data = base64.encodestring(io.getvalue()) | |
| return html.format(data) | |
| if __name__ == '__main__': | |
| app.run() |
@prakashsharma91 This happens because you provide input of type bytes to StringIO, which is meant for String I/O only.
You can make it work by replacing StringIO with BytesIO. You'll then simply have to convert the byte string to a real string and you're good to go. Small example:
io = BytesIO()
fig.savefig(io, format='png')
data = base64.encodestring(io.getvalue()).decode('utf-8')
html = 'data:image/png;base64,{}';
return html.format(data);
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TypeError: string argument expected, got 'bytes'