Backport PR #38041 on branch 1.1.x: BUG: pytables in py39 (#38041)

ci/deps/azure-39.yaml

@@ -15,3 +15,8 @@ dependencies:
   - numpy
   - python-dateutil
   - pytz
+
+  # optional dependencies
+  - pytables
+  - scipy
+  - pyarrow=1.0

doc/source/whatsnew/v1.1.5.rst

@@ -28,6 +28,7 @@ Bug fixes
 - Bug in metadata propagation for ``groupby`` iterator (:issue:`37343`)
 - Bug in indexing on a :class:`Series` with ``CategoricalDtype`` after unpickling (:issue:`37631`)
 - Bug in :class:`RollingGroupby` with the resulting :class:`MultiIndex` when grouping by a label that is in the index (:issue:`37641`)
+- Bug in pytables methods in python 3.9 (:issue:`38041`)
 -
 
 .. ---------------------------------------------------------------------------

pandas/core/computation/pytables.py

@@ -426,6 +426,10 @@ def visit_Subscript(self, node, **kwargs):
         except AttributeError:
             pass
 
+        if isinstance(slobj, Term):
+            # In py39 np.ndarray lookups with Term containing int raise
+            slobj = slobj.value
+
         try:
             return self.const_type(value[slobj], self.env)
         except TypeError as err:

pandas/tests/io/pytables/test_store.py

@@ -4500,7 +4500,7 @@ def test_categorical(self, setup_path):
 
             # Appending must have the same categories
             df3 = df.copy()
-            df3["s"].cat.remove_unused_categories(inplace=True)
+            df3["s"] = df3["s"].cat.remove_unused_categories()
 
             with pytest.raises(ValueError):
                 store.append("df3", df3)