Read single precision fluid field in RAMSES

doc/source/examining/loading_data.rst

@@ -3171,12 +3171,15 @@ There are three way to make yt detect all the particle fields. For example, if y
          particle_metallicity, d
       """
 
-   Each line should contain the name of the field and its data type (``d`` for double precision, ``f`` for single precision, ``i`` for integer and ``l`` for long integer). You can also configure the auto detected fields for fluid types by adding a section ``ramses-hydro``, ``ramses-grav`` or ``ramses-rt`` in the config file. For example, if you customized your gravity files so that they contain the potential, the potential in the previous timestep and the x, y and z accelerations, you can use :
+   Each line should contain the name of the field and its data type (``d`` for double precision, ``f`` for single precision, ``i`` for integer and ``l`` for long integer). You can also configure the auto detected fields for fluid types by adding a section ``ramses-hydro``, ``ramses-grav`` or ``ramses-rt`` in the config file. For example, if you customized your gravity files so that they contain the potential, the potential in the previous timestep and the x, y and z accelerations, all in single-precision, you can use :
 
    .. code-block:: none
 
       [ramses-grav]
-      fields = [ "Potential", "Potential-old", "x-acceleration", "y-acceleration", "z-acceleration" ]
+      fields = [ "Potential,f", "Potential-old,f", "x-acceleration,f", "y-acceleration,f", "z-acceleration,f" ]
+
+   Importantly, the order of the fields should match the order in which they are written in the RAMSES output files.
+   yt will also assume that each entry is formed of a field name followed by its type (``f`` for single precision, ``d`` for double precision), separated by a comma. Field names containing commas are not supported, other precisions (e.g. integers) are not supported either. All fields in a given file type (gravity, hydro, ...) need to have the same precision.
 
 3. New RAMSES way. Recent versions of RAMSES automatically write in their output an ``hydro_file_descriptor.txt`` file that gives information about which field is where. If you wish, you can simply create such a file in the folder containing the ``info_xxxxx.txt`` file
 
@@ -3197,6 +3200,8 @@ There are three way to make yt detect all the particle fields. For example, if y
       11, metallicity, d
 
    It is important to note that this file should not end with an empty line (but in this case with ``11, metallicity, d``).
+   Note that, for grid fields (hydro, gravity, rt), all the fields need to have the same precision (``f`` or ``d``).
+   Combinations are not supported.
 
 .. note::
 

yt/frontends/ramses/data_structures.py

@@ -452,6 +452,7 @@ def _fill_no_ghostzones(self, fd, fields, selector, file_handler):
             fields,
             data,
             oct_handler,
+            file_handler.single_precision,
         )
         return data
 
@@ -507,6 +508,7 @@ def _fill_with_ghostzones(
             fields,
             tr,
             oct_handler,
+            file_handler.single_precision,
             domain_inds=domain_inds,
         )
         return tr
@@ -805,7 +807,7 @@ def __init__(
         if isinstance(fields, str):
             fields = field_aliases[fields]
         """
-        fields:
+        fields: list[tuple[str, str]] | list[str] | None
         An array of hydro variable fields in order of position in the
         hydro_XXXXX.outYYYYY file. If set to None, will try a default set of fields.
 
@@ -822,7 +824,13 @@ def __init__(
         This affects the fields related to cooling and the mean molecular weight.
         """
 
-        self._fields_in_file = fields
+        self._fields_in_file: list[tuple[str, str]] = []
+        if fields:
+            for field in fields:
+                if isinstance(field, tuple):
+                    self._fields_in_file.append(field)
+                else:
+                    self._fields_in_file.append((field, "d"))
         # By default, extra fields have not triggered a warning
         self._warned_extra_fields = defaultdict(lambda: False)
         self._extra_particle_fields = extra_particle_fields