Fix issue with encoding of arrays/list when cache is created

ceos_alos2/hierarchy.py

@@ -11,6 +11,9 @@
 from ceos_alos2.array import Array
 
 
+
+
+
 @dataclass(frozen=True)
 class Variable:
     dims: str | list[str]
@@ -21,6 +24,9 @@ def __post_init__(self):
         if isinstance(self.dims, str):
             # normalize, need the hack
             super().__setattr__("dims", [self.dims])
+        if isinstance(self.data, list):
+            # Infer dtype more carefully, or force appropriate dtype
+            super().__setattr__("data", np.array(self.data, dtype=self._infer_dtype(self.data)))
 
     def __eq__(self, other):
         if not isinstance(other, Variable):
@@ -37,6 +43,23 @@ def __eq__(self, other):
             return self.data == other.data
         else:
             return np.all(self.data == other.data)
+
+    @staticmethod
+    def _infer_dtype(data):
+        if not data:
+            return None
+        first = data[0]
+        if isinstance(first, int):
+            return np.int64  # consistent across platforms
+        elif isinstance(first, float):
+            return np.float64
+        elif isinstance(first, str):
+            # Use fixed-length string to avoid object dtype
+            # CEOS strings are usually ASCII, e.g., 'ALOS-2''
+            max_len = max(len(str(x)) for x in data)
+            return f"S{max_len}"  # or 'U' for unicode
+        else:
+            return None  # let numpy infer
 
     @property
     def ndim(self):