python: concat also Series

py-polars/polars/eager/frame.py

@@ -1441,10 +1441,10 @@ def describe_cast(self: "DataFrame") -> "DataFrame":
                 describe_cast(self.median()),
             ]
         )
-        summary.insert_at_idx(
+        summary.insert_at_idx(  # type: ignore
             0, pl.Series("describe", ["mean", "std", "min", "max", "median"])
         )
-        return summary
+        return summary  # type: ignore
 
     def replace_at_idx(self, index: int, series: "pl.Series") -> None:
         """

py-polars/polars/functions.py

@@ -11,6 +11,7 @@
 
 try:
     from polars.polars import concat_df as _concat_df
+    from polars.polars import concat_series as _concat_series
 
     _DOCUMENTING = False
 except ImportError:
@@ -36,25 +37,31 @@ def get_dummies(df: "pl.DataFrame") -> "pl.DataFrame":
     return df.to_dummies()
 
 
-def concat(dfs: Sequence["pl.DataFrame"], rechunk: bool = True) -> "pl.DataFrame":
+def concat(
+    items: Union[Sequence["pl.DataFrame"], Sequence["pl.Series"]], rechunk: bool = True
+) -> Union["pl.DataFrame", "pl.Series"]:
     """
-    Aggregate all the Dataframes in a List of DataFrames to a single DataFrame.
+    Aggregate all the Dataframes/Series in a List of DataFrames/Series to a single DataFrame/Series.
 
     Parameters
     ----------
-    dfs
-        DataFrames to concatenate.
+    items
+        DataFrames/Series to concatenate.
     rechunk
-        rechunk the final DataFrame.
+        rechunk the final DataFrame/Series.
     """
-    if not len(dfs) > 0:
+    if not len(items) > 0:
         raise ValueError("cannot concat empty list")
 
-    df = pl.wrap_df(_concat_df(dfs))
+    out: Union["pl.Series", "pl.DataFrame"]
+    if isinstance(items[0], pl.DataFrame):
+        out = pl.wrap_df(_concat_df(items))
+    else:
+        out = pl.wrap_s(_concat_series(items))
 
     if rechunk:
-        return df.rechunk()
-    return df
+        return out.rechunk()  # type: ignore
+    return out
 
 
 def repeat(

py-polars/src/conversion.rs

@@ -46,6 +46,11 @@ pub(crate) fn get_df(obj: &PyAny) -> PyResult<DataFrame> {
     Ok(pydf.extract::<PyDataFrame>()?.df)
 }
 
+pub(crate) fn get_series(obj: &PyAny) -> PyResult<Series> {
+    let pydf = obj.getattr("_s")?;
+    Ok(pydf.extract::<PySeries>()?.series)
+}
+
 impl<'a, T> FromPyObject<'a> for Wrap<ChunkedArray<T>>
 where
     T: PyPolarsPrimitiveType,

py-polars/src/lib.rs

@@ -29,7 +29,7 @@ pub mod prelude;
 pub mod series;
 pub mod utils;
 
-use crate::conversion::{get_df, get_pyseq, Wrap};
+use crate::conversion::{get_df, get_pyseq, get_series, Wrap};
 use crate::error::PyPolarsEr;
 use crate::file::get_either_file;
 use crate::prelude::DataType;
@@ -143,6 +143,22 @@ fn concat_df(dfs: &PyAny) -> PyResult<PyDataFrame> {
     Ok(df.into())
 }
 
+#[pyfunction]
+fn concat_series(series: &PyAny) -> PyResult<PySeries> {
+    let (seq, _len) = get_pyseq(series)?;
+    let mut iter = seq.iter()?;
+    let first = iter.next().unwrap()?;
+
+    let mut s = get_series(first)?;
+
+    for res in iter {
+        let item = res?;
+        let item = get_series(item)?;
+        s.append(&item).map_err(PyPolarsEr::from)?;
+    }
+    Ok(s.into())
+}
+
 #[pyfunction]
 fn ipc_schema(py: Python, py_f: PyObject) -> PyResult<PyObject> {
     let metadata = match get_either_file(py_f, false)? {
@@ -184,6 +200,7 @@ fn polars(_py: Python, m: &PyModule) -> PyResult<()> {
     m.add_wrapped(wrap_pyfunction!(concat_str)).unwrap();
     m.add_wrapped(wrap_pyfunction!(concat_lst)).unwrap();
     m.add_wrapped(wrap_pyfunction!(concat_df)).unwrap();
+    m.add_wrapped(wrap_pyfunction!(concat_series)).unwrap();
     m.add_wrapped(wrap_pyfunction!(ipc_schema)).unwrap();
     Ok(())
 }

py-polars/tests/test_series.py

@@ -46,6 +46,14 @@ def test_init_inputs():
         pl.Series("bigint", [2 ** 64])
 
 
+def test_concat():
+    s = pl.Series("a", [2, 1, 3])
+
+    assert pl.concat([s, s]).len() == 6
+    # check if s remains unchanged
+    assert s.len() == 3
+
+
 def test_to_frame():
     assert create_series().to_frame().shape == (2, 1)