19.1.30. camcops_server.cc_modules.cc_plot¶
Copyright (C) 2012-2018 Rudolf Cardinal (rudolf@pobox.com).
This file is part of CamCOPS.
CamCOPS is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.
CamCOPS is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License along with CamCOPS. If not, see <http://www.gnu.org/licenses/>.
PROPER WAY TO USE MATPLOTLIB:
- http://jbarillari.blogspot.co.uk/2009/09/threadsafety-and-matplotlibpylab.html?m=1 # noqa
- https://sjohannes.wordpress.com/2010/06/11/using-matplotlib-in-a-web-application/amp/ # noqa
- http://matplotlib.org/faq/howto_faq.html#howto-webapp
- http://matplotlib.org/examples/api/agg_oo.html#api-agg-oo
In summary: matplotlib is easy to use in a way that has global state, but that will break in a threading application. Using the Figure() API is safe. Thus:
from matplotlib.backends.backend_agg import FigureCanvasAgg as FigureCanvas from matplotlib.figure import Figure
fig = Figure() canvas = FigureCanvas(fig) ax = fig.add_subplot(111) ax.plot([1, 2, 3]) ax.set_title(‘hi mom’) ax.grid(True) ax.set_xlabel(‘time’) ax.set_ylabel(‘volts’) canvas.print_figure(‘test’)