Merge pull request #47 from boutproject/write-int32

Ensure to always write int32

boututils/datafile.py

@@ -654,8 +654,10 @@ def find_dim(dim):
 
         # Write attributes, if present
         try:
-            for attrname in data.attributes:
-                var.setncattr(attrname, data.attributes[attrname])
+            for attrname, attrval in data.attributes.items():
+                if isinstance(attrval, int):
+                    attrval = np.int32(attrval)
+                var.setncattr(attrname, attrval)
         except AttributeError:
             pass
 
@@ -950,8 +952,7 @@ def write(self, name, data, info=False):
             )
 
         try:
-            for attrname in data.attributes:
-                attrval = data.attributes[attrname]
+            for attrname, attrval in data.attributes.items():
                 if type(attrval) == str:
                     attrval = attrval.encode(encoding="utf-8")
                 self.handle[name].attrs.create(attrname, attrval)