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Default Thumbnail¶
By default, the last image output of a notebook will be used as its thumbnail. Without an image output, a placeholder will be used. See a notebook with no thumbnail for an example.
However, if a thumbnail is explicitly assigned by Using Cell Metadata to Select a Thumbnail, Using a Cell Tag to Select a Thumbnail or Specifying a Thumbnail File, these methods will take precedence.
[1]:
import matplotlib.pyplot as plt
import numpy as np
Although the next cell contains an image (a plot), it won’t be used as the thumbnail because it’s not the last in the notebook, and we haven’t explicitly tagged it.
[2]:
fig, ax = plt.subplots(figsize=[6, 3])
x = np.linspace(-5, 5, 50)
ax.plot(x, np.sinc(x));
---------------------------------------------------------------------------
AttributeError Traceback (most recent call last)
Cell In[2], line 1
----> 1 fig, ax = plt.subplots(figsize=[6, 3])
2 x = np.linspace(-5, 5, 50)
3 ax.plot(x, np.sinc(x));
File /usr/lib/python3/dist-packages/matplotlib/pyplot.py:1450, in subplots(nrows, ncols, sharex, sharey, squeeze, width_ratios, height_ratios, subplot_kw, gridspec_kw, **fig_kw)
1304 def subplots(nrows=1, ncols=1, *, sharex=False, sharey=False, squeeze=True,
1305 width_ratios=None, height_ratios=None,
1306 subplot_kw=None, gridspec_kw=None, **fig_kw):
1307 """
1308 Create a figure and a set of subplots.
1309
(...)
1448
1449 """
-> 1450 fig = figure(**fig_kw)
1451 axs = fig.subplots(nrows=nrows, ncols=ncols, sharex=sharex, sharey=sharey,
1452 squeeze=squeeze, subplot_kw=subplot_kw,
1453 gridspec_kw=gridspec_kw, height_ratios=height_ratios,
1454 width_ratios=width_ratios)
1455 return fig, axs
File /usr/lib/python3/dist-packages/matplotlib/_api/deprecation.py:454, in make_keyword_only.<locals>.wrapper(*args, **kwargs)
448 if len(args) > name_idx:
449 warn_deprecated(
450 since, message="Passing the %(name)s %(obj_type)s "
451 "positionally is deprecated since Matplotlib %(since)s; the "
452 "parameter will become keyword-only %(removal)s.",
453 name=name, obj_type=f"parameter of {func.__name__}()")
--> 454 return func(*args, **kwargs)
File /usr/lib/python3/dist-packages/matplotlib/pyplot.py:783, in figure(num, figsize, dpi, facecolor, edgecolor, frameon, FigureClass, clear, **kwargs)
773 if len(allnums) == max_open_warning >= 1:
774 _api.warn_external(
775 f"More than {max_open_warning} figures have been opened. "
776 f"Figures created through the pyplot interface "
(...)
780 f"Consider using `matplotlib.pyplot.close()`.",
781 RuntimeWarning)
--> 783 manager = new_figure_manager(
784 num, figsize=figsize, dpi=dpi,
785 facecolor=facecolor, edgecolor=edgecolor, frameon=frameon,
786 FigureClass=FigureClass, **kwargs)
787 fig = manager.canvas.figure
788 if fig_label:
File /usr/lib/python3/dist-packages/matplotlib/pyplot.py:358, in new_figure_manager(*args, **kwargs)
356 def new_figure_manager(*args, **kwargs):
357 """Create a new figure manager instance."""
--> 358 _warn_if_gui_out_of_main_thread()
359 return _get_backend_mod().new_figure_manager(*args, **kwargs)
File /usr/lib/python3/dist-packages/matplotlib/pyplot.py:336, in _warn_if_gui_out_of_main_thread()
334 def _warn_if_gui_out_of_main_thread():
335 warn = False
--> 336 if _get_required_interactive_framework(_get_backend_mod()):
337 if hasattr(threading, 'get_native_id'):
338 # This compares native thread ids because even if Python-level
339 # Thread objects match, the underlying OS thread (which is what
340 # really matters) may be different on Python implementations with
341 # green threads.
342 if threading.get_native_id() != threading.main_thread().native_id:
File /usr/lib/python3/dist-packages/matplotlib/pyplot.py:207, in _get_backend_mod()
198 """
199 Ensure that a backend is selected and return it.
200
201 This is currently private, but may be made public in the future.
202 """
203 if _backend_mod is None:
204 # Use __getitem__ here to avoid going through the fallback logic (which
205 # will (re)import pyplot and then call switch_backend if we need to
206 # resolve the auto sentinel)
--> 207 switch_backend(dict.__getitem__(rcParams, "backend"))
208 return _backend_mod
File /usr/lib/python3/dist-packages/matplotlib/pyplot.py:265, in switch_backend(newbackend)
262 rcParamsOrig["backend"] = "agg"
263 return
--> 265 backend_mod = importlib.import_module(
266 cbook._backend_module_name(newbackend))
268 required_framework = _get_required_interactive_framework(backend_mod)
269 if required_framework is not None:
File /usr/lib/python3.12/importlib/__init__.py:90, in import_module(name, package)
88 break
89 level += 1
---> 90 return _bootstrap._gcd_import(name[level:], package, level)
File <frozen importlib._bootstrap>:1387, in _gcd_import(name, package, level)
File <frozen importlib._bootstrap>:1360, in _find_and_load(name, import_)
File <frozen importlib._bootstrap>:1310, in _find_and_load_unlocked(name, import_)
File <frozen importlib._bootstrap>:488, in _call_with_frames_removed(f, *args, **kwds)
File <frozen importlib._bootstrap>:1387, in _gcd_import(name, package, level)
File <frozen importlib._bootstrap>:1360, in _find_and_load(name, import_)
File <frozen importlib._bootstrap>:1331, in _find_and_load_unlocked(name, import_)
File <frozen importlib._bootstrap>:935, in _load_unlocked(spec)
File <frozen importlib._bootstrap_external>:995, in exec_module(self, module)
File <frozen importlib._bootstrap>:488, in _call_with_frames_removed(f, *args, **kwds)
File /usr/lib/python3/dist-packages/matplotlib_inline/__init__.py:1
----> 1 from . import backend_inline, config # noqa
3 __version__ = "0.2.1"
5 # we can't ''.join(...) otherwise finding the version number at build time requires
6 # import which introduces IPython and matplotlib at build time, and thus circular
7 # dependencies.
File /usr/lib/python3/dist-packages/matplotlib_inline/backend_inline.py:236
231 ip.events.unregister("post_run_cell", configure_once)
233 ip.events.register("post_run_cell", configure_once)
--> 236 _enable_matplotlib_integration()
239 def _fetch_figure_metadata(fig):
240 """Get some metadata to help with displaying a figure."""
File /usr/lib/python3/dist-packages/matplotlib_inline/backend_inline.py:218, in _enable_matplotlib_integration()
216 backend = matplotlib.get_backend(auto_select=False)
217 else:
--> 218 backend = matplotlib.rcParams._get("backend")
220 if ip and backend in ("inline", "module://matplotlib_inline.backend_inline"):
221 from IPython.core.pylabtools import activate_matplotlib
AttributeError: 'RcParams' object has no attribute '_get'
But the next cell is the last containing an image in the notebook, so its last image output will be used as the thumbnail.
[3]:
display(fig)
fig, ax = plt.subplots(figsize=[6, 3])
x = np.linspace(-5, 5, 50)
ax.plot(x, -np.sinc(x), color='red');
---------------------------------------------------------------------------
NameError Traceback (most recent call last)
Cell In[3], line 1
----> 1 display(fig)
2 fig, ax = plt.subplots(figsize=[6, 3])
3 x = np.linspace(-5, 5, 50)
NameError: name 'fig' is not defined