psyplot · Chilipp · Nov 21, 2021 · Oct 15, 2021 · Oct 15, 2021 · Oct 15, 2021
diff --git a/.appveyor.yml b/.appveyor.yml
@@ -24,7 +24,7 @@ install:
     - cmd: endlocal
     - cmd: 'SET PYTHONWARNINGS=ignore:mode:DeprecationWarning:docutils.io:245'
     - cmd: "IF NOT DEFINED APPVEYOR_REPO_TAG_NAME (SET GIT_BRANCH=%APPVEYOR_REPO_BRANCH%)"
-    - cmd: "IF NOT DEFINED APPVEYOR_REPO_TAG_NAME (conda config --add channels psyplot/label/%APPVEYOR_REPO_BRANCH%)"
+    - cmd: "IF NOT DEFINED APPVEYOR_REPO_TAG_NAME (conda config --add channels psyplot/label/%APPVEYOR_REPO_BRANCH:/=-%)"
 
 build: off
 
@@ -37,7 +37,7 @@ test_script:
 deploy_script:
     - cmd: "
         IF NOT DEFINED APPVEYOR_REPO_TAG_NAME (
-            deploy-conda-recipe -l %APPVEYOR_REPO_BRANCH% -py %PYTHON_VERSION% ci/conda-recipe
+            deploy-conda-recipe -l %APPVEYOR_REPO_BRANCH:/=-% -py %PYTHON_VERSION% ci/conda-recipe
         ) ELSE (
             deploy-conda-recipe -py %PYTHON_VERSION% ci/conda-recipe
         )"
diff --git a/.circleci/config.yml b/.circleci/config.yml
@@ -1,7 +1,7 @@
 version: 2.1
 
 orbs:
-  psyplot: psyplot/psyplot-ci-orb@1.5.24
+  psyplot: psyplot/psyplot-ci-orb@1.5.27
   mattermost-plugin-notify: nathanaelhoun/mattermost-plugin-notify@1.2.0
 
 executors:

diff --git a/CHANGELOG.rst b/CHANGELOG.rst
@@ -1,3 +1,28 @@
+v1.4.1
+======
+Compatibility fixes and minor improvements
+
+Added
+-----
+- An abstract ``convert_coordinate`` method has been implemented for the
+  ``Plotter`` and ``Formatoption`` class that can be used in subclasses to
+  convert coordinates for the required visualization. The default
+  implementation does nothing (see
+  `#39 <https://github.com/psyplot/psyplot/pull/39>`__)
+
+Fixed
+-----
+- the update method now only takes the coordinates that are dimensions in the
+  dataset see `#39 <https://github.com/psyplot/psyplot/pull/39>`__
+
+Changed
+-------
+- loading more than one variables into a ``DataArray`` now first selects the
+  corresponding dimensions, then puts it into a single ``DataArray``. This
+  avoids loading the entire data (see
+  `#39 <https://github.com/psyplot/psyplot/pull/39>`__)
+
+
 v1.4.0
 ======
 Compatibility fixes and LGPL license

diff --git a/psyplot/data.py b/psyplot/data.py
@@ -145,7 +145,7 @@ def _fix_times(dims):
     # https://github.com/pydata/xarray/issues/4283
     for key, val in dims.items():
         if np.issubdtype(np.asarray(val).dtype, np.datetime64):
-            dims[key] = to_datetime(val)
+            dims[key] = to_datetime([val])[0]
 
 
 @docstrings.get_sections(base='setup_coords')
@@ -2650,18 +2650,19 @@ def filter_attrs(item):
             name = dims.pop('name')
         else:
             name = list(self.arr.coords['variable'].values)
+        base_dims = self.base[name].dims
         if method == 'isel':
             self.idims.update(dims)
             dims = self.idims
-            for dim in set(self.base[name].dims) - set(dims):
+            for dim in set(base_dims) - set(dims):
                 dims[dim] = slice(None)
             for dim in set(dims) - set(self.base[name].dims):
                 del dims[dim]
             res = self.base[name].isel(**dims).to_array()
         else:
             self._idims = None
             for key, val in six.iteritems(self.arr.coords):
-                if key != 'variable':
+                if key in base_dims and key != 'variable':
                     dims.setdefault(key, val)
             kws = dims.copy()
             # the sel method does not work with slice objects
@@ -2724,7 +2725,8 @@ def filter_attrs(item):
             self._idims = None
             old_dims = self.arr.dims[:]
             for key, val in six.iteritems(self.arr.coords):
-                dims.setdefault(key, val)
+                if key in base_var.dims:
+                    dims.setdefault(key, val)
             kws = dims.copy()
             # the sel method does not work with slice objects
             if not any(isinstance(idx, slice) for idx in dims.values()):
@@ -3664,7 +3666,8 @@ def from_dataset(cls, base, method='isel', default_slice=None,
         default_slice: indexer
             Index (e.g. 0 if `method` is 'isel') that shall be used for
             dimensions not covered by `dims` and `furtherdims`. If None, the
-            whole slice will be used.
+            whole slice will be used. Note that the `default_slice` is always
+            based on the `isel` method.
         decoder: CFDecoder or dict
             Arguments for the decoder. This can be one of
 
@@ -3771,19 +3774,22 @@ def sel_method(key, dims, name=None):
                 elif (isinstance(name, six.string_types) or
                       not utils.is_iterable(name)):
                     arr = base[name]
+                    decoder = get_decoder(arr)
+                    dims = decoder.correct_dims(arr, dims)
                 else:
                     arr = base[list(name)]
-                add_missing_dimensions(arr)
-                if not isinstance(arr, xr.DataArray):
-                    arr = ds2arr(arr)
+                    decoder = get_decoder(base[name[0]])
+                    dims = decoder.correct_dims(base[name[0]], dims)
                 def_slice = slice(None) if default_slice is None else \
                     default_slice
-                decoder = get_decoder(arr)
-                dims = decoder.correct_dims(arr, dims)
                 dims.update({
                     dim: def_slice for dim in set(arr.dims).difference(
                         dims) if dim != 'variable'})
-                ret = squeeze_array(arr.isel(**dims))
+                add_missing_dimensions(arr)
+                ret = arr.isel(**dims)
+                if not isinstance(ret, xr.DataArray):
+                    ret = ds2arr(ret)
+                ret = squeeze_array(ret)
                 # delete the variable dimension for the idims
                 dims.pop('variable', None)
                 ret.psy.init_accessor(arr_name=key, base=base, idims=dims,
@@ -3796,28 +3802,40 @@ def sel_method(key, dims, name=None):
                 elif (isinstance(name, six.string_types) or
                       not utils.is_iterable(name)):
                     arr = base[name]
+                    decoder = get_decoder(arr)
+                    dims = decoder.correct_dims(arr, dims)
                 else:
                     arr = base[list(name)]
-                add_missing_dimensions(arr)
-                if not isinstance(arr, xr.DataArray):
-                    arr = ds2arr(arr)
-                # idims will be calculated by the array (maybe not the most
-                # efficient way...)
-                decoder = get_decoder(arr)
-                dims = decoder.correct_dims(arr, dims)
+                    decoder = get_decoder(base[name[0]])
+                    dims = decoder.correct_dims(base[name[0]], dims)
                 if default_slice is not None:
-                    dims.update({
-                        key: default_slice for key in set(arr.dims).difference(
-                            dims) if key != 'variable'})
+                    if isinstance(default_slice, slice):
+                        dims.update({
+                            dim: default_slice
+                            for dim in set(arr.dims).difference(dims)
+                            if dim != 'variable'})
+                    else:
+                        dims.update({
+                            dim: arr.coords[dim][default_slice]
+                            for dim in set(arr.dims).difference(dims)
+                            if dim != 'variable'})
                 kws = dims.copy()
+                kws['method'] = method
                 # the sel method does not work with slice objects
-                if not any(isinstance(idx, slice) for idx in dims.values()):
-                    kws['method'] = method
+                for dim, val in dims.items():
+                    if isinstance(val, slice):
+                        if val == slice(None):
+                            kws.pop(dim)  # the full slice is the default
+                        else:
+                            kws.pop("method", None)
+                add_missing_dimensions(arr)
                 try:
                     ret = arr.sel(**kws)
                 except KeyError:
                     _fix_times(kws)
                     ret = arr.sel(**kws)
+                if not isinstance(ret, xr.DataArray):
+                    ret = ds2arr(ret)
                 ret = squeeze_array(ret)
                 ret.psy.init_accessor(arr_name=key, base=base, decoder=decoder)
                 return maybe_load(ret)

diff --git a/psyplot/plotter.py b/psyplot/plotter.py
@@ -752,6 +752,42 @@ def remove(self):
         are removed by the usual :meth:`matplotlib.axes.Axes.clear` method."""
         pass
 
+    @docstrings.get_extended_summary(base="Formatoption.convert_coordinate")
+    @docstrings.get_sections(
+        base="Formatoption.convert_coordinate",
+        sections=["Parameters", "Returns"]
+    )
+    def convert_coordinate(self, coord, *variables):
+        """Convert a coordinate to units necessary for the plot.
+
+        This method takes a single coordinate variable (e.g. the `bounds` of a
+        coordinate, or the coordinate itself) and transforms the units that the
+        plotter requires.
+
+        One might also provide additional `variables` that are supposed to be
+        on the same unit, in case the given `coord` does not specify a `units`
+        attribute. `coord` might be a CF-conform `bounds` variable, and one of
+        the variables might be the corresponding `coordinate`.
+
+        Parameters
+        ----------
+        coord: xr.Variable
+            The variable to transform
+        ``*variables``
+            The variables that are on the same unit as `coord`
+
+        Returns
+        -------
+        xr.Variable
+            The transformed `coord`
+
+        Notes
+        -----
+        By default, this method uses the :meth:`~Plotter.convert_coordinate`
+        method of the :attr:`plotter`.
+        """
+        return self.plotter.convert_coordinate(coord, *variables)
+
 
 class DictFormatoption(Formatoption):
     """
@@ -2434,3 +2470,24 @@ def _get_sample_projection(cls):
         """Returns None. May be subclassed to return a projection that
         can be used when creating a subplot"""
         pass
+
+    @docstrings.dedent
+    def convert_coordinate(self, coord, *variables):
+        """Convert a coordinate to units necessary for the plot.
+
+        %(Formatoption.convert_coordinate.summary_ext)s
+
+        Parameters
+        ----------
+        %(Formatoption.convert_coordinate.parameters)s
+
+        Returns
+        -------
+        %(Formatoption.convert_coordinate.returns)s
+
+        Notes
+        -----
+        This method is supposed to be implemented by subclasses. The default
+        implementation by the :class:`Plotter` class does nothing.
+        """
+        return coord
diff --git a/tests/test_data.py b/tests/test_data.py
@@ -1335,6 +1335,18 @@ def test_from_dataset_15_decoder_kws(self):
                                          decoder=dict(x={'myx'}))
         self.assertEqual(l[0].psy.decoder.x, {'myx'})
 
+    def test_from_dataset_16_default_slice(self):
+        """Test selection with default_slice=0"""
+        variables, coords = self._from_dataset_test_variables
+        ds = xr.Dataset(variables, coords)
+        l = self.list_class.from_dataset(ds, ydim=2, default_slice=0, method=None,
+                                         name=['v0', 'v2'])
+        self.assertEqual(len(l), 2)
+        self.assertEqual(set(l.names), {'v0', 'v2'})
+        for arr in l:
+            self.assertEqual(arr.ydim, 2,
+                             msg="Wrong ydim slice for " + arr.name)
+
 
     def test_array_info(self):
         variables, coords = self._from_dataset_test_variables