fix null commutativity (#3479)

pola-rs · May 23, 2022 · 8575195 · 8575195
1 parent 0dfea6d
commit 8575195
Show file tree

Hide file tree

Showing 2 changed files with 20 additions and 4 deletions.
diff --git a/polars/polars-core/src/chunked_array/comparison.rs b/polars/polars-core/src/chunked_array/comparison.rs
@@ -69,14 +69,14 @@ where
                 if let Some(value) = rhs.get(0) {
                     self.equal(value)
                 } else {
-                    BooleanChunked::full("", false, self.len())
+                    self.is_null()
                 }
             }
             (1, _) => {
                 if let Some(value) = self.get(0) {
                     rhs.equal(value)
                 } else {
-                    BooleanChunked::full("", false, rhs.len())
+                    self.is_null()
                 }
             }
             _ => {
@@ -94,14 +94,14 @@ where
                 if let Some(value) = rhs.get(0) {
                     self.not_equal(value)
                 } else {
-                    BooleanChunked::full("", false, self.len())
+                    self.is_not_null()
                 }
             }
             (1, _) => {
                 if let Some(value) = self.get(0) {
                     rhs.not_equal(value)
                 } else {
-                    BooleanChunked::full("", false, rhs.len())
+                    self.is_not_null()
                 }
             }
             _ => {

diff --git a/polars/tests/it/lazy/expressions/arity.rs b/polars/tests/it/lazy/expressions/arity.rs
@@ -226,3 +226,19 @@ fn test_when_then_otherwise_sum_in_agg() -> Result<()> {
 
     Ok(())
 }
+
+#[test]
+fn test_null_commutativity() {
+    let df = DataFrame::new_no_checks(vec![]);
+    let out = df
+        .lazy()
+        .select([
+            lit(1).neq(NULL.lit()).alias("a"),
+            NULL.lit().neq(1).alias("b"),
+        ])
+        .collect()
+        .unwrap();
+
+    assert_eq!(out.column("a").unwrap().get(0), AnyValue::Boolean(true));
+    assert_eq!(out.column("b").unwrap().get(0), AnyValue::Boolean(true));
+}