Fix approach to detecting assignment for gte/lte operators (#13285)

Resolves #13185

Authors:
  - Vyas Ramasubramani (https://github.com/vyasr)

Approvers:
  - Bradley Dice (https://github.com/bdice)

URL: #13285

python/cudf/cudf/core/dataframe.py

@@ -7139,13 +7139,14 @@ def eval(self, expr: str, inplace: bool = False, **kwargs):
                 "Keyword arguments other than `inplace` are not supported"
             )
 
-        # Have to use a regex match to avoid capturing "=="
-        includes_assignment = re.search("[^=]=[^=]", expr) is not None
+        # Have to use a regex match to avoid capturing ==, >=, or <=
+        equals_sign_regex = "[^=><]=[^=]"
+        includes_assignment = re.search(equals_sign_regex, expr) is not None
 
         # Check if there were multiple statements. Filter out empty lines.
         statements = tuple(filter(None, expr.strip().split("\n")))
         if len(statements) > 1 and any(
-            re.search("[^=]=[^=]", st) is None for st in statements
+            re.search(equals_sign_regex, st) is None for st in statements
         ):
             raise ValueError(
                 "Multi-line expressions are only valid if all expressions "

python/cudf/cudf/tests/test_dataframe.py

@@ -9794,6 +9794,7 @@ def df_eval(request):
         ("a / b", float),
         ("a * b", int),
         ("a > b", int),
+        ("a >= b", int),
         ("a > b > c", int),
         ("a > b < c", int),
         ("a & b", int),
@@ -9835,7 +9836,7 @@ def test_dataframe_eval(df_eval, expr, dtype):
     assert_eq(expect, got, check_names=False)
 
     # Test inplace
-    if re.search("[^=]=[^=]", expr) is not None:
+    if re.search("[^=><]=[^=]", expr) is not None:
         pdf_eval = df_eval.to_pandas()
         pdf_eval.eval(expr, inplace=True)
         df_eval.eval(expr, inplace=True)