Use null count to check for contiguous slices (#2849)

pola-rs · Mar 8, 2022 · d98e752 · d98e752
1 parent 3e1071d
commit d98e752
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Showing 2 changed files with 21 additions and 1 deletion.
diff --git a/polars/polars-core/src/chunked_array/mod.rs b/polars/polars-core/src/chunked_array/mod.rs
@@ -506,7 +506,7 @@ where
 {
     /// Contiguous slice
     pub fn cont_slice(&self) -> Result<&[T::Native]> {
-        if self.chunks.len() == 1 && !self.chunks[0].has_validity() {
+        if self.chunks.len() == 1 && self.chunks[0].null_count() == 0 {
             Ok(self.downcast_iter().next().map(|arr| arr.values()).unwrap())
         } else {
             Err(PolarsError::ComputeError("cannot take slice".into()))

diff --git a/polars/tests/it/joins.rs b/polars/tests/it/joins.rs
@@ -29,3 +29,23 @@ fn join_nans_outer() -> Result<()> {
     assert_eq!(res.shape(), (4, 4));
     Ok(())
 }
+
+#[test]
+#[cfg(feature = "lazy")]
+fn join_empty_datasets() -> Result<()> {
+    let a = DataFrame::new(Vec::from([Series::new_empty("foo", &DataType::Int64)])).unwrap();
+    let b = DataFrame::new(Vec::from([
+        Series::new_empty("foo", &DataType::Int64),
+        Series::new_empty("bar", &DataType::Int64),
+    ]))
+    .unwrap();
+
+    a.lazy()
+        .groupby([col("foo")])
+        .agg([all().last()])
+        .inner_join(b.lazy(), "foo", "foo")
+        .collect()
+        .unwrap();
+
+    Ok(())
+}