fix explode

pola-rs · Sep 19, 2021 · d7d63b1 · d7d63b1
1 parent d053cd0
commit d7d63b1
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Showing 3 changed files with 10 additions and 2 deletions.
diff --git a/polars/polars-core/src/chunked_array/ops/explode.rs b/polars/polars-core/src/chunked_array/ops/explode.rs
@@ -240,9 +240,10 @@ impl ChunkExplode for ListChunked {
                 }
             }
 
-            let values = Series::try_from(("", values)).unwrap();
+            let values = Series::try_from((self.name(), values)).unwrap();
             values.explode_by_offsets(offsets)
         };
+        debug_assert_eq!(s.name(), self.name());
         Ok((s, offsets_buf))
     }
 }

diff --git a/polars/polars-core/src/frame/explode.rs b/polars/polars-core/src/frame/explode.rs
@@ -72,7 +72,7 @@ impl DataFrame {
     ///  +-----+-----+-----+
     /// ```
     pub fn explode<'a, J, S: Selection<'a, J>>(&self, columns: S) -> Result<DataFrame> {
-        // We need to sort the column by order of original occurence. Otherwise the insert by index
+        // We need to sort the column by order of original occurrence. Otherwise the insert by index
         // below will panic
         let mut columns = self.select_series(columns)?;
         columns.sort_by(|sa, sb| {

diff --git a/py-polars/tests/test_df.py b/py-polars/tests/test_df.py
@@ -372,6 +372,13 @@ def test_head_tail():
     assert df.tail(100).height == 10
 
 
+def test_explode():
+    df = pl.DataFrame({"letters": ["c", "a"], "nrs": [[1, 2], [1, 3]]})
+    out = df.explode("nrs")
+    out["letters"].to_list() == ["c", "c", "a", "a"]
+    out["nrs"].to_list() == [1, 2, 1, 3]
+
+
 def test_groupby():
     df = pl.DataFrame(
         {