matplotlib - ImportError: No module named _tkinter - matplotlib

Question

I have a simple notebook with the following code:
%matplotlib inline
However, when running it I get the following error:
ImportError: No module named _tkinter
I have another notebook in the same project, and that one is able to run the statement without issue.
The data science experience is a managed service so you don't have root access to install _tkinter.
Full stacktrace:
ImportErrorTraceback (most recent call last)
<ipython-input-43-5f9c00ae8c2d> in <module>()
----> 1 get_ipython().magic(u'matplotlib inline')
2
3 import matplotlib.pyplot as plt
4 #import numpy as np
5
/usr/local/src/bluemix_jupyter_bundle.v20/notebook/lib/python2.7/site-packages/IPython/core/interactiveshell.pyc in magic(self, arg_s)
2161 magic_name, _, magic_arg_s = arg_s.partition(' ')
2162 magic_name = magic_name.lstrip(prefilter.ESC_MAGIC)
-> 2163 return self.run_line_magic(magic_name, magic_arg_s)
2164
2165 #-------------------------------------------------------------------------
/usr/local/src/bluemix_jupyter_bundle.v20/notebook/lib/python2.7/site-packages/IPython/core/interactiveshell.pyc in run_line_magic(self, magic_name, line)
2082 kwargs['local_ns'] = sys._getframe(stack_depth).f_locals
2083 with self.builtin_trap:
-> 2084 result = fn(*args,**kwargs)
2085 return result
2086
<decorator-gen-106> in matplotlib(self, line)
/usr/local/src/bluemix_jupyter_bundle.v20/notebook/lib/python2.7/site-packages/IPython/core/magic.pyc in <lambda>(f, *a, **k)
191 # but it's overkill for just that one bit of state.
192 def magic_deco(arg):
--> 193 call = lambda f, *a, **k: f(*a, **k)
194
195 if callable(arg):
/usr/local/src/bluemix_jupyter_bundle.v20/notebook/lib/python2.7/site-packages/IPython/core/magics/pylab.pyc in matplotlib(self, line)
98 print("Available matplotlib backends: %s" % backends_list)
99 else:
--> 100 gui, backend = self.shell.enable_matplotlib(args.gui)
101 self._show_matplotlib_backend(args.gui, backend)
102
/usr/local/src/bluemix_jupyter_bundle.v20/notebook/lib/python2.7/site-packages/IPython/core/interactiveshell.pyc in enable_matplotlib(self, gui)
2949 gui, backend = pt.find_gui_and_backend(self.pylab_gui_select)
2950
-> 2951 pt.activate_matplotlib(backend)
2952 pt.configure_inline_support(self, backend)
2953
/usr/local/src/bluemix_jupyter_bundle.v20/notebook/lib/python2.7/site-packages/IPython/core/pylabtools.pyc in activate_matplotlib(backend)
293 matplotlib.rcParams['backend'] = backend
294
--> 295 import matplotlib.pyplot
296 matplotlib.pyplot.switch_backend(backend)
297
/gpfs/fs01/user/sdd1-7e9fd7607be53e-39ca506ba762/.local/lib/python2.7/site-packages/matplotlib/pyplot.py in <module>()
112
113 from matplotlib.backends import pylab_setup
--> 114 _backend_mod, new_figure_manager, draw_if_interactive, _show = pylab_setup()
115
116 _IP_REGISTERED = None
/gpfs/fs01/user/sdd1-7e9fd7607be53e-39ca506ba762/.local/lib/python2.7/site-packages/matplotlib/backends/__init__.pyc in pylab_setup()
30 # imports. 0 means only perform absolute imports.
31 backend_mod = __import__(backend_name,
---> 32 globals(),locals(),[backend_name],0)
33
34 # Things we pull in from all backends
/gpfs/fs01/user/sdd1-7e9fd7607be53e-39ca506ba762/.local/lib/python2.7/site-packages/matplotlib/backends/backend_tkagg.py in <module>()
4
5 from matplotlib.externals import six
----> 6 from matplotlib.externals.six.moves import tkinter as Tk
7 from matplotlib.externals.six.moves import tkinter_filedialog as FileDialog
8
/gpfs/fs01/user/sdd1-7e9fd7607be53e-39ca506ba762/.local/lib/python2.7/site-packages/matplotlib/externals/six.pyc in load_module(self, fullname)
197 mod = self.__get_module(fullname)
198 if isinstance(mod, MovedModule):
--> 199 mod = mod._resolve()
200 else:
201 mod.__loader__ = self
/gpfs/fs01/user/sdd1-7e9fd7607be53e-39ca506ba762/.local/lib/python2.7/site-packages/matplotlib/externals/six.pyc in _resolve(self)
111
112 def _resolve(self):
--> 113 return _import_module(self.mod)
114
115 def __getattr__(self, attr):
/gpfs/fs01/user/sdd1-7e9fd7607be53e-39ca506ba762/.local/lib/python2.7/site-packages/matplotlib/externals/six.pyc in _import_module(name)
78 def _import_module(name):
79 """Import module, returning the module after the last dot."""
---> 80 __import__(name)
81 return sys.modules[name]
82
/usr/local/src/bluemix_jupyter_bundle.v20/notebook/lib/python2.7/lib-tk/Tkinter.py in <module>()
37 # Attempt to configure Tcl/Tk without requiring PATH
38 import FixTk
---> 39 import _tkinter # If this fails your Python may not be configured for Tk
40 tkinter = _tkinter # b/w compat for export
41 TclError = _tkinter.TclError
ImportError: No module named _tkinter

Answer 1

So the fix was quite simple - I just had to restart the kernel using the kernel menu item in the notebook.
I had experienced the same problem when running ipython locally on my laptop and the solution was to install tkinter, so I wasn't expecting the answer to be as simple as restarting the kernel.
Another time I received this error message, restarting the kernel did not work. I had to:
change the spark backend
download the notebook to file
delete the notebook in DSX
create a new notebook from the downloaded notebook