Strict eqdsk precision (#17)

* revert precision change

* Enforce strict specification

eqdsk/file.py

@@ -283,6 +283,8 @@ def write(
         file_path: str,
         file_format: str = "json",
         json_kwargs: dict | None = None,
+        *,
+        strict_spec: bool = True,
     ):
         """Write the EQDSK data to file in the given format.
 
@@ -296,6 +298,9 @@ def write(
         json_kwargs:
             Key word arguments to pass to the ``json.dump`` call. Only
             used if ``format`` is 'json'.
+        strict_spec:
+            As https://w3.pppl.gov/ntcc/TORAY/G_EQDSK.pdf arrays have the format
+            5e16.9, disabling this changes the format to 5ES23.16e2
         """
         if file_format == "json":
             json_kwargs = {} if json_kwargs is None else json_kwargs
@@ -305,7 +310,7 @@ def write(
                 "You are in the 21st century. "
                 "Are you sure you want to be making an EDQSK in this day and age?"
             )
-            _write_eqdsk(file_path, self.to_dict())
+            _write_eqdsk(file_path, self.to_dict(), strict_spec=strict_spec)
 
     def update(self, eqdsk_data: dict[str, Any]):
         """Update this object's data with values from a dictionary.
@@ -516,7 +521,7 @@ def _derive_psinorm(fpol) -> np.ndarray:
     return np.linspace(0, 1, len(fpol))
 
 
-def _write_eqdsk(file_path: str | Path, data: dict):
+def _write_eqdsk(file_path: str | Path, data: dict, *, strict_spec: bool = True):
     """Write data out to a text file in G-EQDSK format.
 
     Parameters
@@ -525,6 +530,9 @@ def _write_eqdsk(file_path: str | Path, data: dict):
         The full path string of the file to be created
     data:
         Dictionary of EQDSK data.
+    strict_spec:
+        As https://w3.pppl.gov/ntcc/TORAY/G_EQDSK.pdf arrays have the format
+        5e16.9, disabling this changes the format to 5ES23.16e2
     """
     file_path = Path(file_path)
     if file_path.suffix not in EQDSK_EXTENSIONS:
@@ -622,7 +630,7 @@ def write_array(fortran_format: ff.FortranRecordWriter, array: np.ndarray):
         # Create FortranRecordWriter objects with the Fortran format
         # edit descriptors to be used in the G-EQDSK output.
         f2000 = ff.FortranRecordWriter("a48,3i4")
-        f2020 = ff.FortranRecordWriter("5ES23.16e2")
+        f2020 = ff.FortranRecordWriter("5e16.9" if strict_spec else "5ES23.16e2")
         f2022 = ff.FortranRecordWriter("2i5")
         fCSTM = ff.FortranRecordWriter("i5")
 
@@ -648,5 +656,6 @@ def write_array(fortran_format: ff.FortranRecordWriter, array: np.ndarray):
 
         # Output of coilset information. This is an extension to the
         # regular eqdsk format.
-        write_line(fCSTM, ["ncoil"])
-        write_array(f2020, coil)
+        if data["ncoil"] > 0:
+            write_line(fCSTM, ["ncoil"])
+            write_array(f2020, coil)

tests/_helpers.py

@@ -23,7 +23,7 @@ def get_private_dir():
     return None
 
 
-def read_strict_geqdsk(file_path):
+def read_strict_geqdsk(file_path, *, strict_spec=True):
     """
     Reads an input EQDSK file in, assuming strict adherence to the
     GEQDSK format. Used to check bluemira outputs can be read by
@@ -41,7 +41,7 @@ def read_strict_geqdsk(file_path):
     # Create FortranRecordReader objects with the Fortran format
     # edit descriptors to be used to parse the G-EQDSK input.
     f2000 = ff.FortranRecordReader("a48,3i4")
-    f2020 = ff.FortranRecordReader("5ES23.16e2")
+    f2020 = ff.FortranRecordReader("5e16.9" if strict_spec else "5ES23.16e2")
     f2022 = ff.FortranRecordReader("2i5")
     fCSTM = ff.FortranRecordReader("i5")
 

tests/test_file.py

@@ -180,7 +180,7 @@ def test_read_write_doesnt_change_file_private(file, ftype, ind, tmp_path):
                 eqd_default.to_dict(), eqd_default_nc.to_dict(), verbose=True
             )
 
-        eqd_default.write(tmp_path / "test", file_format=ftype)
+        eqd_default.write(tmp_path / "test", file_format=ftype, strict_spec=False)
 
         eqd_test = EQDSKInterface.from_file(tmp_path / f"test.{ftype}", no_cocos=True)
         eqd_test_d = eqd_test.to_dict()