Add isfinite and finite_data to Surveys (#332)

CHANGELOG.rst

@@ -21,6 +21,11 @@ latest
     set the tolerance for the gradient often to a lower value, which saves
     computation time.
 
+- Survey
+
+  - New attributes ``isfinite`` and ``finite_data``. Former returns the indices
+    of the finite data, latter returns directly the finite data.
+
 - Electrodes
 
   - Fixed ``TxMagneticDipole``-representation and improved documentation of the

emg3d/surveys.py

@@ -713,6 +713,17 @@ def _rec_types_coord(self, source):
         indices = self._irec_types
         return [tuple(self._rec_coord[source][ind].T) for ind in indices]
 
+    @property
+    def isfinite(self):
+        """Return indices of the finite data."""
+        if not hasattr(self, '_isfinite'):
+            self._isfinite = np.isfinite(self.data.observed.data)
+        return self._isfinite
+
+    def finite_data(self, data='observed'):
+        """Return finite elements of selected `data`."""
+        return self.data[data].data[self.isfinite]
+
 
 def random_noise(standard_deviation, mean_noise=0.0, ntype='white_noise'):
     r"""Return random noise for given inputs.

tests/test_surveys.py

@@ -284,6 +284,8 @@ def test_add_noise(self):
         assert np.all(np.isnan(survey.data.test1.data[:, -1:, :]))
         # Ensure no others are none
         assert np.sum(np.isnan(survey.data.test1.data)) == 3
+        assert survey.isfinite.sum() == 21
+        assert survey.finite_data().shape == (21,)
 
         # No cutting
         survey.add_noise(min_offset=0, min_amplitude=10e-50, add_to='test2')