Merge pull request #175 from PhilFreeman/snapPlotFix

Snap plot fix

README.rst

@@ -58,7 +58,7 @@ Configuration
 The kernel can be configured by adding an ``octave_kernel_config.py`` file to the
 ``jupyter`` config path.  The ``OctaveKernel`` class offers ``plot_settings``, ``inline_toolkit``,
 ``kernel_json``, and ``cli_options`` as configurable traits.  The available plot settings are:
-'format', 'backend', 'width', 'height', and 'resolution'.
+'format', 'backend', 'width', 'height', 'resolution', and 'plot_dir'.
 
 .. code:: bash
 
@@ -119,6 +119,37 @@ An error that starts with ``gnuplot> set terminal aqua enhanced title`` can be f
 adding ``setenv("GNUTERM","qt");`` to ``~/.octaverc`` on MacOS or by installing
 ``gunplot-x11`` and using ``setenv("GNUTERM", "X11")``.
 
+Octave-Snap (Linux)
+~~~~~~~~~~~~~~~~~~~
+You can check if you are using a snap version on Linux by checking the path to your Octave
+installation.
+
+.. code:: shell
+
+    which octave
+
+If the returned path has ``snap`` in it, then Octave is running in a container and you will need to configure the kernel appropriately.
+
+1) Set the environment variable ``OCTAVE_EXECUTABLE="octave"``
+
+.. code:: shell
+
+    echo export OCTAVE_EXECUTABLE=\"octave\" >> ~/.bashrc
+
+2) Make a directory for the temporary plot directories that the kernel uses. This *cannot* be a hidden directory.
+
+.. code:: shell
+
+    mkdir ~/octavePlots
+
+3) Set ``plot_dir`` to point to your plot directory in ``octave_kernel_config.py``.
+
+.. code:: shell
+
+	c.OctaveKernel.plot_settings = dict(plot_dir='<home>/octavePlots')
+
+where ``<home>`` is the absolute path to your home directory. Do not use ``~`` as this resolves to a different location for Octave-Snap.
+
 
 Blank Plot
 ~~~~~~~~~~

octave_kernel/kernel.py

@@ -189,7 +189,7 @@ def plot_settings(self, settings):
 
         # Remove "None" keys so we can use setdefault below.
         keys = ['format', 'backend', 'width', 'height', 'resolution',
-                'backend', 'name']
+                'backend', 'name', 'plot_dir']
         for key in keys:
             if key in settings and settings.get(key, None) is None:
                 del settings[key]
@@ -200,6 +200,7 @@ def plot_settings(self, settings):
         settings.setdefault('height', -1)
         settings.setdefault('resolution', 0)
         settings.setdefault('name', 'Figure')
+        settings.setdefault('plot_dir', None)
 
         cmds = []
         if settings['backend'] == 'inline':
@@ -268,7 +269,7 @@ def make_figures(self, plot_dir=None):
         wid = settings['width']
         hgt = settings['height']
         name = settings['name']
-        plot_dir = plot_dir or tempfile.mkdtemp()
+        plot_dir = plot_dir or tempfile.mkdtemp(dir=settings['plot_dir'])
         plot_dir = plot_dir.replace(os.path.sep, '/')
 
         # Do not overwrite any existing plot files.
@@ -448,9 +449,11 @@ def _get_executable(self):
         # Attempt to get the octave executable
         executable = os.environ.get('OCTAVE_EXECUTABLE', None)
         if executable:
-            executable = which(executable)
-            if 'octave-cli' not in executable:
-                raise OSError('OCTAVE_EXECUTABLE does not point to an octave-cli file, please see README')
+            fullpath = which(executable)
+            if 'snap' not in fullpath:
+                executable = fullpath
+                if 'octave-cli' not in executable:
+                    raise OSError('OCTAVE_EXECUTABLE does not point to an octave-cli file, please see README')
         else:
             executable = which('octave-cli')
             if not executable: