Merge pull request #30853 from anntzer/close

timhoffm · web-flow · commit 420750ca3771 · 2025-12-14T01:17:33.000+01:00
Minor doc fixes re: close()ing figures.
diff --git a/doc/users/faq.rst b/doc/users/faq.rst
@@ -281,7 +281,7 @@ locators as desired because the two axes are independent.
 Generate images without having a window appear
 ----------------------------------------------
 
-The recommended approach since matplotlib 3.1 is to explicitly create a Figure
+The recommended approach since Matplotlib 3.1 is to explicitly create a Figure
 instance::
 
     from matplotlib.figure import Figure
@@ -292,12 +292,10 @@ instance::
 
 This prevents any interaction with GUI frameworks and the window manager.
 
-It's alternatively still possible to use the pyplot interface. Instead of
-calling `matplotlib.pyplot.show`, call `matplotlib.pyplot.savefig`.
-
-Additionally, you must ensure to close the figure after saving it. Not
-closing the figure is a memory leak, because pyplot keeps references
-to all not-yet-shown figures::
+It's alternatively still possible to use the pyplot interface: instead of
+calling `matplotlib.pyplot.show`, call `matplotlib.pyplot.savefig`. In that
+case, you must close the figure after saving it. Not closing the figure causes
+a memory leak, because pyplot keeps references to all not-yet-shown figures. ::
 
     import matplotlib.pyplot as plt
     plt.plot([1, 2, 3])
diff --git a/galleries/examples/user_interfaces/canvasagg.py b/galleries/examples/user_interfaces/canvasagg.py
@@ -32,10 +32,6 @@
 from matplotlib.figure import Figure
 
 fig = Figure(figsize=(5, 4), dpi=100)
-# A canvas must be manually attached to the figure (pyplot would automatically
-# do it).  This is done by instantiating the canvas with the figure as
-# argument.
-canvas = FigureCanvasAgg(fig)
 
 # Do some plotting.
 ax = fig.add_subplot()
@@ -45,8 +41,12 @@
 # etc.).
 fig.savefig("test.png")
 
-# Option 2: Retrieve a memoryview on the renderer buffer, and convert it to a
+# Option 2 (low-level approach to directly save to a numpy array): Manually
+# attach a canvas to the figure (pyplot or savefig would automatically do
+# it), by instantiating the canvas with the figure as argument; then draw the
+# figure, retrieve a memoryview on the renderer buffer, and convert it to a
 # numpy array.
+canvas = FigureCanvasAgg(fig)
 canvas.draw()
 rgba = np.asarray(canvas.buffer_rgba())
 # ... and pass it to PIL.
diff --git a/galleries/examples/user_interfaces/web_application_server_sgskip.py b/galleries/examples/user_interfaces/web_application_server_sgskip.py
@@ -5,7 +5,7 @@
 
 When using Matplotlib in a web server it is strongly recommended to not use
 pyplot (pyplot maintains references to the opened figures to make
-`~.matplotlib.pyplot.show` work, but this will cause memory leaks unless the
+`~.pyplot.show` work, but this will cause memory leaks unless the
 figures are properly closed).
 
 Since Matplotlib 3.1, one can directly create figures using the `.Figure`
@@ -45,21 +45,14 @@ def hello():
 # %%
 #
 # Since the above code is a Flask application, it should be run using the
-# `flask command-line tool <https://flask.palletsprojects.com/en/latest/cli/>`_
-# Assuming that the working directory contains this script:
-#
-# Unix-like systems
+# `flask command-line tool <https://flask.palletsprojects.com/en/latest/cli/>`_:
+# run
 #
 # .. code-block:: console
 #
-#  FLASK_APP=web_application_server_sgskip flask run
-#
-# Windows
-#
-# .. code-block:: console
+#    flask --app web_application_server_sgskip run
 #
-#  set FLASK_APP=web_application_server_sgskip
-#  flask run
+# from the directory containing this script.
 #
 #
 # Clickable images for HTML
diff --git a/lib/matplotlib/pyplot.py b/lib/matplotlib/pyplot.py
@@ -1263,7 +1263,7 @@ def close(fig: None | int | str | Figure | Literal["all"] = None) -> None:
     -----
     pyplot maintains a reference to figures created with `figure()`. When
     work on the figure is completed, it should be closed, i.e. deregistered
-    from pyplot, to free its memory (see also :rc:figure.max_open_warning).
+    from pyplot, to free its memory (see also :rc:`figure.max_open_warning`).
     Closing a figure window created by `show()` automatically deregisters the
     figure. For all other use cases, most prominently `savefig()` without
     `show()`, the figure must be deregistered explicitly using `close()`.

Original file line number	Diff line number	Diff line change
`@@ -5,7 +5,7 @@`
`5`	`5`
`6`	`6`	`When using Matplotlib in a web server it is strongly recommended to not use`
`7`	`7`	`pyplot (pyplot maintains references to the opened figures to make`
`8`		-`~.matplotlib.pyplot.show` work, but this will cause memory leaks unless the
	`8`	+`~.pyplot.show` work, but this will cause memory leaks unless the
`9`	`9`	`figures are properly closed).`
`10`	`10`
`11`	`11`	Since Matplotlib 3.1, one can directly create figures using the `.Figure`
`@@ -45,21 +45,14 @@ def hello():`
`45`	`45`	`# %%`
`46`	`46`	`#`
`47`	`47`	`# Since the above code is a Flask application, it should be run using the`
`48`		-# `flask command-line tool <https://flask.palletsprojects.com/en/latest/cli/>`_
`49`		`-# Assuming that the working directory contains this script:`
`50`		`-#`
`51`		`-# Unix-like systems`
	`48`	+# `flask command-line tool <https://flask.palletsprojects.com/en/latest/cli/>`_:
	`49`	`+# run`
`52`	`50`	`#`
`53`	`51`	`# .. code-block:: console`
`54`	`52`	`#`
`55`		`-# FLASK_APP=web_application_server_sgskip flask run`
`56`		`-#`
`57`		`-# Windows`
`58`		`-#`
`59`		`-# .. code-block:: console`
	`53`	`+# flask --app web_application_server_sgskip run`
`60`	`54`	`#`
`61`		`-# set FLASK_APP=web_application_server_sgskip`
`62`		`-# flask run`
	`55`	`+# from the directory containing this script.`
`63`	`56`	`#`
`64`	`57`	`#`
`65`	`58`	`# Clickable images for HTML`