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--- other:python:matplotlib_by_jyp [2020/02/11 13:55] – [Starting (and more) with matplotlib] jypeter
+++ other:python:matplotlib_by_jyp [2020/03/31 16:20] – Added offline plot jypeter
@@ Line 187: / Line 187: @@
 ===== Misc Matplotlib tricks =====
-  * Specifying the background color of a plot (e.g. when plotting a masked variable and you don't want the masked areas to be white)
+==== Creating a plot offline ====
-    * ''# make the background dark gray (call this before the contourf)''\\ ''plt.gca().patch.set_color('.25')''\\ ''plt.contourf(d)''\\ ''plt.show()''
-    * [[https://stackoverflow.com/questions/9797520/masking-part-of-a-contourf-plot-in-matplotlib|trick source]]
+You may need to create a plot offline when your network connection is not good enough, you don't have an X server running to display the plot (possibly because the script is running on a cluster), etc... This is easily done with the following code:
+<code># offline_plot = False
+offline_plot = True
+import matplotlib as mpl
+if offline_plot:
+    # Define the graphic back-end BEFORE importing pyplot
+    mpl.use('Agg')
+# Import the rest of the matplotlib based modules
+import matplotlib.pyplot as plt
+[ ...your actual code... ]
+# Done at last! Save the result
+my_page.savefig(out_name, dpi=300, transparent=True, bbox_inches='tight')
+if not offline_plot:
+    # Enter the interactive mode to display the plot
+    plt.show()</code>
+Note: see also [[https://matplotlib.org/gallery/user_interfaces/canvasagg.html|CanvasAgg demo]] for a pure offline plot, and [[https://matplotlib.org/faq/howto_faq.html?highlight=web#howto-webapp|How to use Matplotlib in a web application server]]. But the code above is much easier!
+==== Specifying the background color of a plot ====
+e.g. You need to plot a masked variable, but you don't want the masked areas to be white
+<code># make the background dark gray (call this before the contourf)
+plt.gca().patch.set_color('.25')
+plt.contourf(d)
+plt.show()</code>
+[[https://stackoverflow.com/questions/9797520/masking-part-of-a-contourf-plot-in-matplotlib|trick source]]