Add is_nan aliases

python/datafusion/expr.py

@@ -1226,6 +1226,12 @@ def isnan(self) -> Expr:
 
         return F.isnan(self)
 
+    def is_nan(self) -> Expr:
+        """Returns true if a given number is +NaN or -NaN otherwise returns false."""
+        from . import functions as F
+
+        return F.is_nan(self)
+
     def degrees(self) -> Expr:
         """Converts the argument from radians to degrees."""
         from . import functions as F

python/datafusion/functions/__init__.py

@@ -217,6 +217,7 @@ def _warn_if_expr_for_literal_arg(
     "initcap",
     "inner_product",
     "instr",
+    "is_nan",
     "isnan",
     "iszero",
     "lag",
@@ -413,6 +414,11 @@ def isnan(expr: Expr) -> Expr:
     return Expr(f.isnan(expr.expr))
 
 
+def is_nan(expr: Expr) -> Expr:
+    """Returns true if a given number is +NaN or -NaN otherwise returns false."""
+    return isnan(expr)
+
+
 def nullif(expr1: Expr, expr2: Expr) -> Expr:
     """Returns NULL if expr1 equals expr2; otherwise it returns expr1.
 

python/tests/test_expr.py

@@ -500,6 +500,11 @@ def test_alias_with_metadata(df):
             pa.array([False, True, False, None], type=pa.bool_()),
             id="isnan",
         ),
+        pytest.param(
+            col("e").is_nan(),
+            pa.array([False, True, False, None], type=pa.bool_()),
+            id="is_nan",
+        ),
         pytest.param(
             functions.round(col("a").degrees(), lit(4)),
             pa.array([-42.9718, 28.6479, 0.0, None], type=pa.float64()),

python/tests/test_functions.py

@@ -215,6 +215,15 @@ def test_math_functions():
     )
 
 
+def test_is_nan_alias():
+    ctx = SessionContext()
+    df = ctx.from_pydict({"value": [1.0, np.nan, None]})
+
+    result = df.select(f.is_nan(column("value")).alias("is_nan")).to_pydict()
+
+    assert result == {"is_nan": [False, True, None]}
+
+
 def py_indexof(arr, v):
     try:
         return arr.index(v) + 1