NDCube.fill method

changelog/829.feature.rst

@@ -0,0 +1,2 @@
+Added ``fill_masked`` method to ``NDCube``, a new feature which allows users to replace masked values and uncertainty values with user-given fill values,
+to change the mask values back to False or not (Default),  and to set whether the new instance is returned (Default) or not.

ndcube/ndcube.py

@@ -1330,6 +1330,54 @@ def squeeze(self, axis=None):
         return self[tuple(item)]
 
 
+def fill_masked(self, fill_value, unmask=False, uncertainty_fill_value=None, fill_in_place=False):
+    """
+    Replaces masked data values with input value.
+
+    Returns a new instance or alters values in place.
+
+    Parameters
+    ----------
+    fill_value: `numbers.Number` or scalar `astropy.unit.Quantity`
+        The value to replace masked data with.
+    unmask: `bool`, optional
+        If True, the newly filled masked values are unmasked. If False, they remain masked
+        Default=False
+    uncertainty_fill_value: `numbers.Number` or scalar `astropy.unit.Quantity`, optional
+        The value to replace masked uncertainties with.
+    fill_in_place: `bool`, optional
+        If `True`, the masked values are filled in place.  If `False`, a new instance is returned
+        with masked values filled.  Default=False.
+    """
+    if fill_in_place:
+        new_data = self.data
+        new_uncertainty = self.uncertainty
+        # Unmasking in-place should be handled later.
+    else:
+        new_data = copy.deepcopy(self.data)
+        new_uncertainty = copy.deepcopy(self.uncertainty)
+        new_mask = False if unmask else copy.deepcopy(self.mask)
+
+
+    masked = False if (self.mask is None or self.mask is False or not self.mask.any()) else True
+    if masked:
+            idx_mask = slice(None) is self.mask is True else self.mask # Ensure indexing mask can index the data array.
+            kwargs["data"][self.mask] = fill_value # Boolean indexing in Python.
+        # else, do nothing to the data.
+
+        # if unmask is True, do: change the True mask values to False, otherwise, do nothing to the mask.
+
+        if uncertainty_fill_value is not None:
+            if not self.uncertainty:
+                raise TypeError("Cannot fill uncertainty as uncertainty is None.")
+            new_uncertainty.array[idx_mask] = uncertainty_fill_value
+
+    if not fill_in_place:
+        # Create kwargs dictionary and return a new instance.
+    elif unmask:
+        self.mask = False
+
+
 def _create_masked_array_for_rebinning(data, mask, operation_ignores_mask):
     m = None if (mask is None or mask is False or operation_ignores_mask) else mask
     if m is None: