floatish strings

Author: ianhi

src/zarr/core/dtype/npy/common.py

@@ -61,6 +61,9 @@
 IntishStr = NewType("IntishStr", str)
 """A type for strings that represent integers, like "0" or "42"."""
 
+FloatishStr = NewType("FloatishStr", str)
+"""A type for strings that represent floats, like "3.14" or "-2.5"."""
+
 NumpyEndiannessStr = Literal[">", "<", "="]
 NUMPY_ENDIANNESS_STR: Final = ">", "<", "="
 
@@ -516,6 +519,34 @@ def check_json_intish_str(data: JSON) -> TypeGuard[IntishStr]:
         return True
 
 
+def check_json_floatish_str(data: JSON) -> TypeGuard[FloatishStr]:
+    """
+    Check if a JSON value is a string that represents a float, like "3.14", "-2.5", or "0.0".
+
+    Note: This function is intended to be used AFTER check_json_float_v2/v3, so it only
+    handles regular string representations that those functions don't cover.
+
+    Parameters
+    ----------
+    data : JSON
+        The JSON value to check.
+
+    Returns
+    -------
+    bool
+        True if the data is a string representing a regular float, False otherwise.
+    """
+    if not isinstance(data, str):
+        return False
+
+    try:
+        float(data)
+    except ValueError:
+        return False
+    else:
+        return True
+
+
 def check_json_str(data: JSON) -> TypeGuard[str]:
     """
     Check if a JSON value is a string.

src/zarr/core/dtype/npy/float.py

@@ -19,6 +19,7 @@
     TFloatScalar_co,
     check_json_float_v2,
     check_json_float_v3,
+    check_json_floatish_str,
     endianness_to_numpy_str,
     float_from_json_v2,
     float_from_json_v3,
@@ -270,13 +271,17 @@ def from_json_scalar(self, data: JSON, *, zarr_format: ZarrFormat) -> TFloatScal
         if zarr_format == 2:
             if check_json_float_v2(data):
                 return self._cast_scalar_unchecked(float_from_json_v2(data))
+            elif check_json_floatish_str(data):
+                return self._cast_scalar_unchecked(float(data))
             else:
                 raise TypeError(
                     f"Invalid type: {data}. Expected a float or a special string encoding of a float."
                 )
         elif zarr_format == 3:
             if check_json_float_v3(data):
                 return self._cast_scalar_unchecked(float_from_json_v3(data))
+            elif check_json_floatish_str(data):
+                return self._cast_scalar_unchecked(float(data))
             else:
                 raise TypeError(
                     f"Invalid type: {data}. Expected a float or a special string encoding of a float."