Fix pandas-dev#60494: query doesn't work on DataFrame integer column names

Author: David-msggc

doc/source/whatsnew/v3.0.0.rst

@@ -826,6 +826,7 @@ Other
 - Bug in :meth:`DataFrame.eval` and :meth:`DataFrame.query` which did not allow to use ``tan`` function. (:issue:`55091`)
 - Bug in :meth:`DataFrame.query` where using duplicate column names led to a ``TypeError``. (:issue:`59950`)
 - Bug in :meth:`DataFrame.query` which raised an exception or produced incorrect results when expressions contained backtick-quoted column names containing the hash character ``#``, backticks, or characters that fall outside the ASCII range (U+0001..U+007F). (:issue:`59285`) (:issue:`49633`)
+- Bug in :meth:`DataFrame.query` which raised an exception when querying integer column names using backticks. (:issue:`60494`)
 - Bug in :meth:`DataFrame.shift` where passing a ``freq`` on a DataFrame with no columns did not shift the index correctly. (:issue:`60102`)
 - Bug in :meth:`DataFrame.sort_index` when passing ``axis="columns"`` and ``ignore_index=True`` and ``ascending=False`` not returning a :class:`RangeIndex` columns (:issue:`57293`)
 - Bug in :meth:`DataFrame.transform` that was returning the wrong order unless the index was monotonically increasing. (:issue:`57069`)

pandas/core/frame.py

@@ -4790,6 +4790,12 @@ def eval(self, expr: str, *, inplace: bool = False, **kwargs) -> Any | None:
         inplace = validate_bool_kwarg(inplace, "inplace")
         kwargs["level"] = kwargs.pop("level", 0) + 1
         index_resolvers = self._get_index_resolvers()
+
+        if any(isinstance(col, int) for col in self.columns):
+            self = self.rename(
+                columns={col: f"{col}" for col in self.columns if isinstance(col, int)}
+            )
+
         column_resolvers = self._get_cleaned_column_resolvers()
         resolvers = column_resolvers, index_resolvers
         if "target" not in kwargs:

pandas/tests/frame/test_query_eval.py

@@ -1345,6 +1345,11 @@ def test_start_with_spaces(self, df):
         expect = df[" A"] + df["  "]
         tm.assert_series_equal(res, expect)
 
+    def test_ints(self, df):
+        res = df.query("`1` == 7")
+        expect = df[df[1] == 7]
+        tm.assert_frame_equal(res, expect)
+
     def test_lots_of_operators_string(self, df):
         res = df.query("`  &^ :!€$?(} >    <++*''  ` > 4")
         expect = df[df["  &^ :!€$?(} >    <++*''  "] > 4]