simplify 240-byte scalar type

Author: tasansal

src/mdio/builder/schemas/dtype.py

@@ -32,7 +32,7 @@ class ScalarType(StrEnum):
     COMPLEX64 = "complex64"
     COMPLEX128 = "complex128"
     COMPLEX256 = "complex256"
-    HEADERS_V3 = "r1920"  # Raw number of BITS, must be a multiple of 8
+    BYTES240 = "V240"  # fixed-width 240-byte string, used for raw v0/1/2 trace headers
 
 
 class StructuredField(CamelCaseStrictModel):

src/mdio/constants.py

@@ -64,5 +64,5 @@ class ZarrFormat(IntEnum):
     ScalarType.COMPLEX64: complex(np.nan, np.nan),
     ScalarType.COMPLEX128: complex(np.nan, np.nan),
     ScalarType.COMPLEX256: complex(np.nan, np.nan),
-    ScalarType.HEADERS_V3: b"\x00" * 240,
+    ScalarType.BYTES240: b"\x00" * 240,
 }

src/mdio/converters/segy.py

@@ -380,7 +380,7 @@ def enhanced_add_variables() -> None:
             name="raw_headers",
             long_name="Raw Headers",
             dimensions=mdio_template._dim_names[:-1],  # All dimensions except vertical
-            data_type=ScalarType.HEADERS_V3,
+            data_type=ScalarType.BYTES240,
             compressor=Blosc(cname=BloscCname.zstd),
             coordinates=None,  # No coordinates as specified
             metadata=VariableMetadata(chunk_grid=chunk_metadata),

src/mdio/converters/type_converter.py

@@ -78,8 +78,6 @@ def to_structured_type(data_type: np_dtype) -> StructuredType:
 def to_numpy_dtype(data_type: ScalarType | StructuredType) -> np_dtype:
     """Get the numpy dtype for a variable."""
     if isinstance(data_type, ScalarType):
-        if data_type == ScalarType.HEADERS_V3:
-            return np_dtype("|V240")
         return np_dtype(data_type.value)
     if isinstance(data_type, StructuredType):
         return np_dtype([(f.name, f.format.value) for f in data_type.fields])