String dtype: allow string dtype in query/eval with default numexpr engine

pandas/core/computation/eval.py

@@ -14,7 +14,10 @@
 from pandas.util._exceptions import find_stack_level
 from pandas.util._validators import validate_bool_kwarg
 
-from pandas.core.dtypes.common import is_extension_array_dtype
+from pandas.core.dtypes.common import (
+    is_extension_array_dtype,
+    is_string_dtype,
+)
 
 from pandas.core.computation.engines import ENGINES
 from pandas.core.computation.expr import (
@@ -345,10 +348,13 @@ def eval(
         parsed_expr = Expr(expr, engine=engine, parser=parser, env=env)
 
         if engine == "numexpr" and (
-            is_extension_array_dtype(parsed_expr.terms.return_type)
+            (
+                is_extension_array_dtype(parsed_expr.terms.return_type)
+                and not is_string_dtype(parsed_expr.terms.return_type)
+            )
             or getattr(parsed_expr.terms, "operand_types", None) is not None
             and any(
-                is_extension_array_dtype(elem)
+                (is_extension_array_dtype(elem) and not is_string_dtype(elem))
                 for elem in parsed_expr.terms.operand_types
             )
         ):

pandas/core/computation/expr.py

@@ -21,6 +21,8 @@
 
 from pandas.errors import UndefinedVariableError
 
+from pandas.core.dtypes.common import is_string_dtype
+
 import pandas.core.common as com
 from pandas.core.computation.ops import (
     ARITH_OPS_SYMS,
@@ -524,10 +526,12 @@ def _maybe_evaluate_binop(
         elif self.engine != "pytables":
             if (
                 getattr(lhs, "return_type", None) == object
+                or is_string_dtype(getattr(lhs, "return_type", None))
                 or getattr(rhs, "return_type", None) == object
+                or is_string_dtype(getattr(rhs, "return_type", None))
             ):
                 # evaluate "==" and "!=" in python if either of our operands
-                # has an object return type
+                # has an object or string return type
                 return self._maybe_eval(res, eval_in_python + maybe_eval_in_python)
         return res
 

pandas/tests/frame/test_query_eval.py

@@ -4,8 +4,6 @@
 import numpy as np
 import pytest
 
-from pandas._config import using_string_dtype
-
 from pandas.errors import (
     NumExprClobberingError,
     UndefinedVariableError,
@@ -762,7 +760,6 @@ def test_inf(self, op, f, engine, parser):
         result = df.query(q, engine=engine, parser=parser)
         tm.assert_frame_equal(result, expected)
 
-    @pytest.mark.xfail(using_string_dtype(), reason="TODO(infer_string)")
     def test_check_tz_aware_index_query(self, tz_aware_fixture):
         # https://github.com/pandas-dev/pandas/issues/29463
         tz = tz_aware_fixture
@@ -775,6 +772,7 @@ def test_check_tz_aware_index_query(self, tz_aware_fixture):
         tm.assert_frame_equal(result, expected)
 
         expected = DataFrame(df_index)
+        expected.columns = expected.columns.astype(object)
         result = df.reset_index().query('"2018-01-03 00:00:00+00" < time')
         tm.assert_frame_equal(result, expected)
 
@@ -1072,7 +1070,7 @@ def test_query_with_string_columns(self, parser, engine):
             with pytest.raises(NotImplementedError, match=msg):
                 df.query("a in b and c < d", parser=parser, engine=engine)
 
-    def test_object_array_eq_ne(self, parser, engine, using_infer_string):
+    def test_object_array_eq_ne(self, parser, engine):
         df = DataFrame(
             {
                 "a": list("aaaabbbbcccc"),
@@ -1081,14 +1079,11 @@ def test_object_array_eq_ne(self, parser, engine, using_infer_string):
                 "d": np.random.default_rng(2).integers(9, size=12),
             }
         )
-        warning = RuntimeWarning if using_infer_string and engine == "numexpr" else None
-        with tm.assert_produces_warning(warning):
-            res = df.query("a == b", parser=parser, engine=engine)
+        res = df.query("a == b", parser=parser, engine=engine)
         exp = df[df.a == df.b]
         tm.assert_frame_equal(res, exp)
 
-        with tm.assert_produces_warning(warning):
-            res = df.query("a != b", parser=parser, engine=engine)
+        res = df.query("a != b", parser=parser, engine=engine)
         exp = df[df.a != df.b]
         tm.assert_frame_equal(res, exp)
 
@@ -1128,15 +1123,13 @@ def test_query_with_nested_special_character(self, parser, engine):
         ],
     )
     def test_query_lex_compare_strings(
-        self, parser, engine, op, func, using_infer_string
+        self, parser, engine, op, func
     ):
         a = Series(np.random.default_rng(2).choice(list("abcde"), 20))
         b = Series(np.arange(a.size))
         df = DataFrame({"X": a, "Y": b})
 
-        warning = RuntimeWarning if using_infer_string and engine == "numexpr" else None
-        with tm.assert_produces_warning(warning):
-            res = df.query(f'X {op} "d"', engine=engine, parser=parser)
+        res = df.query(f'X {op} "d"', engine=engine, parser=parser)
         expected = df[func(df.X, "d")]
         tm.assert_frame_equal(res, expected)
 
@@ -1400,15 +1393,13 @@ def test_expr_with_column_name_with_backtick(self):
         expected = df[df["a`b"] < 2]
         tm.assert_frame_equal(result, expected)
 
-    @pytest.mark.xfail(using_string_dtype(), reason="TODO(infer_string)")
     def test_expr_with_string_with_backticks(self):
         # GH 59285
         df = DataFrame(("`", "`````", "``````````"), columns=["#backticks"])
         result = df.query("'```' < `#backticks`")
         expected = df["```" < df["#backticks"]]
         tm.assert_frame_equal(result, expected)
 
-    @pytest.mark.xfail(using_string_dtype(), reason="TODO(infer_string)")
     def test_expr_with_string_with_backticked_substring_same_as_column_name(self):
         # GH 59285
         df = DataFrame(("`", "`````", "``````````"), columns=["#backticks"])
@@ -1439,7 +1430,6 @@ def test_expr_with_column_names_with_special_characters(self, col1, col2, expr):
         expected = df[df[col1] < df[col2]]
         tm.assert_frame_equal(result, expected)
 
-    @pytest.mark.xfail(using_string_dtype(), reason="TODO(infer_string)")
     def test_expr_with_no_backticks(self):
         # GH 59285
         df = DataFrame(("aaa", "vvv", "zzz"), columns=["column_name"])
@@ -1483,15 +1473,13 @@ def test_expr_with_quote_opened_before_backtick_and_quote_is_unmatched(self):
         ):
             df.query("`column-name` < 'It`s that\\'s \"quote\" #hash")
 
-    @pytest.mark.xfail(using_string_dtype(), reason="TODO(infer_string)")
     def test_expr_with_quote_opened_before_backtick_and_quote_is_matched_at_end(self):
         # GH 59285
         df = DataFrame(("aaa", "vvv", "zzz"), columns=["column-name"])
         result = df.query("`column-name` < 'It`s that\\'s \"quote\" #hash'")
         expected = df[df["column-name"] < 'It`s that\'s "quote" #hash']
         tm.assert_frame_equal(result, expected)
 
-    @pytest.mark.xfail(using_string_dtype(), reason="TODO(infer_string)")
     def test_expr_with_quote_opened_before_backtick_and_quote_is_matched_in_mid(self):
         # GH 59285
         df = DataFrame(("aaa", "vvv", "zzz"), columns=["column-name"])