feat(rust, python): raise error on invalid binary cmp

polars/polars-lazy/src/physical_plan/expressions/binary.rs

@@ -7,6 +7,7 @@ use polars_core::series::unstable::UnstableSeries;
 use polars_core::POOL;
 use rayon::prelude::*;
 
+use crate::physical_plan::errors::expression_err;
 use crate::physical_plan::state::ExecutionState;
 use crate::prelude::*;
 
@@ -108,7 +109,15 @@ impl PhysicalExpr for BinaryExpr {
                 || self.right.evaluate(df, &state),
             )
         });
-        apply_operator_owned(lhs?, rhs?, self.op)
+        let lhs = lhs?;
+        let rhs = rhs?;
+        let lhs_len = lhs.len();
+        let rhs_len = rhs.len();
+        if lhs_len != rhs_len && !(lhs_len == 1 || rhs_len == 1) {
+            let msg = format!("Cannot evaluate two Series of different length. Got lhs of length: {lhs_len} and rhs of length: {rhs_len}.");
+            return Err(expression_err!(msg, self.expr, ComputeError));
+        }
+        apply_operator_owned(lhs, rhs, self.op)
     }
 
     #[allow(clippy::ptr_arg)]

py-polars/tests/unit/test_errors.py

@@ -418,3 +418,17 @@ def test_err_on_multiple_column_expansion() -> None:
                 "d": [4],
             }
         ).select([pl.col(["a", "b"]) + pl.col(["c", "d"])])
+
+
+def test_compare_different_len() -> None:
+    df = pl.DataFrame(
+        {
+            "idx": list(range(5)),
+        }
+    )
+
+    s = pl.Series([2, 5, 8])
+    with pytest.raises(
+        pl.ComputeError, match=r"annot evaluate two Series of different length"
+    ):
+        df.filter(pl.col("idx") == s)