BUG: do not normalise field names to upper case in Idefix vtk (#251)

Co-authored-by: Clément Robert <cr52@protonmail.com>
Co-authored-by: Marc Van den Bossche <marc.vanden-bossche@univ-grenoble-alpes.fr>

yt_idefix/_io/vtk_io.py

@@ -204,7 +204,9 @@ def read_grid_coordinates(
     return Coordinates(coords[0], coords[1], coords[2], array_shape)
 
 
-def read_field_offset_index(fh: BinaryIO, shape: Shape) -> dict[str, int]:
+def read_field_offset_index(
+    fh: BinaryIO, shape: Shape, *, upper_case_varnames: bool
+) -> dict[str, int]:
     # assuming fh is correctly positioned (read_grid_coordinates must be called first)
     retv: dict[str, int] = {}
 
@@ -215,10 +217,8 @@ def read_field_offset_index(fh: BinaryIO, shape: Shape) -> dict[str, int]:
         s = line.decode()
         datatype, varname, dtype = s.split()
 
-        # some versions of Pluto define field names in lower case
-        # so we normalize to upper case to avoid duplicating data
-        # in IdefixVtkFieldInfo.known_other_fields
-        varname = varname.upper()
+        if upper_case_varnames:
+            varname = varname.upper()
 
         if datatype == "SCALARS":
             next(fh)

yt_idefix/data_structures.py

@@ -725,11 +725,16 @@ def _parse_parameter_file(self):
         super()._parse_parameter_file()
         # from here self.geometry is assumed to be set
 
+        # some versions of Pluto define field names in lower case
+        # so we normalize to upper case to avoid duplicating data
+        # in BaseVtkFields.known_other_fields
+        normalize_varnames = self.dataset_type == "pluto-vtk"
+
         # parse the grid
         with open(self.filename, "rb") as fh:
             coords = vtk_io.read_grid_coordinates(fh, geometry=self.geometry)
             self._field_offset_index = vtk_io.read_field_offset_index(
-                fh, coords.array_shape
+                fh, coords.array_shape, upper_case_varnames=normalize_varnames
             )
         self._detected_field_list = list(self._field_offset_index.keys())