PyVortex array subclasses (#2194)

Downcast a PyArray to an encoding-specific array when we return it.

Author: gatesn

docs/python/api/arrays.rst

@@ -7,10 +7,10 @@ functions, serialized, and otherwise manipulated as a generic array.
 
 There are two ways of "downcasting" an array for more specific access patterns:
 
-1. Into an encoding-specific array, like `vortex.encoding.BitPackedArray`.vortex.
+1. Into an encoding-specific array, like `vortex.BitPackedArray`.vortex.
 2. Into a type-specific array, like `vortex.array.BoolTypeArray`.
 
-Be careful to note that :class:`vortex.encoding.BoolArray` represents an array that stores physical data
+Be careful to note that :class:`vortex.BoolArray` represents an array that stores physical data
  as a bit-buffer of booleans, vs `vortex.array.BoolTypeArray` which represents any array that has a logical
  type of boolean.
 
@@ -20,9 +20,52 @@ Factory Functions
 .. autofunction:: vortex.array
 
 
-Type Classes
-------------
+Base Class
+----------
 
 .. autoclass:: vortex.Array
    :members:
    :special-members: __len__
+
+
+Builtin Encodings
+-----------------
+
+.. autoclass:: vortex.ChunkedArray
+   :members:
+
+
+.. autoclass:: vortex.ConstantArray
+   :members:
+
+
+.. autoclass:: vortex.NullArray
+   :members:
+
+
+.. autoclass:: vortex.BoolArray
+   :members:
+
+
+.. autoclass:: vortex.PrimitiveArray
+   :members:
+
+
+.. autoclass:: vortex.VarBinArray
+   :members:
+
+
+.. autoclass:: vortex.VarBinViewArray
+   :members:
+
+
+.. autoclass:: vortex.StructArray
+   :members:
+
+
+.. autoclass:: vortex.ListArray
+   :members:
+
+
+.. autoclass:: vortex.ExtensionArray
+   :members:

docs/python/api/compress.rst

@@ -0,0 +1,4 @@
+Compression
+===========
+
+.. autofunction:: vortex.compress

docs/python/api/encoding.rst

@@ -6,8 +6,8 @@ Python API
 
    arrays
    dtypes
-   encoding
+   scalars
+   expr
+   compress
    io
    dataset
-   expr
-   scalars

docs/python/api/index.rst

@@ -1,4 +1,16 @@
 from . import _lib
+from ._lib.arrays import (
+    BoolArray,
+    ChunkedArray,
+    ConstantArray,
+    ExtensionArray,
+    ListArray,
+    NullArray,
+    PrimitiveArray,
+    StructArray,
+    VarBinArray,
+    VarBinViewArray,
+)
 from ._lib.compress import compress
 from ._lib.dtype import (
     BinaryDType,
@@ -37,9 +49,20 @@
 assert _lib, "Ensure we eagerly import the Vortex native library"
 
 __all__ = [
-    "Array",
     "array",
     "compress",
+    # Arrays and builtin encodings
+    "Array",
+    "ConstantArray",
+    "ChunkedArray",
+    "NullArray",
+    "BoolArray",
+    "PrimitiveArray",
+    "VarBinArray",
+    "VarBinViewArray",
+    "StructArray",
+    "ListArray",
+    "ExtensionArray",
     # DTypes
     "DType",
     "NullDType",

pyvortex/python/vortex/__init__.py

@@ -1,4 +1,4 @@
-from typing import Any
+from typing import Any, final
 
 import numpy as np
 import pandas as pd
@@ -32,3 +32,36 @@ class Array:
     def to_polars_dataframe(self) -> pl.DataFrame: ...
     def to_polars_series(self) -> pl.Series: ...
     def to_pylist(self) -> list: ...
+
+@final
+class NullArray(Array): ...
+
+@final
+class BoolArray(Array): ...
+
+@final
+class PrimitiveArray(Array): ...
+
+@final
+class VarBinArray(Array): ...
+
+@final
+class VarBinViewArray(Array): ...
+
+@final
+class StructArray(Array):
+    def field(self, name: str) -> Array: ...
+
+@final
+class ListArray(Array): ...
+
+@final
+class ExtensionArray(Array): ...
+
+@final
+class ConstantArray(Array):
+    def scalar(self) -> vx.Scalar: ...
+
+@final
+class ChunkedArray(Array):
+    def chunks(self) -> list[Array]: ...

pyvortex/python/vortex/_lib/arrays.pyi

@@ -1,11 +1,5 @@
-from typing import Any, final
+from typing import Any
 
 import pyarrow as pa
 
-import vortex as vx
-
 def _encode(obj: Any) -> pa.Array: ...
-@final
-class BoolArray(vx.Array):
-    def __new__(cls, array: vx.Array) -> BoolArray: ...
-    def true_count(self) -> int: ...

pyvortex/python/vortex/_lib/encoding.pyi

@@ -0,0 +1,24 @@
+use itertools::Itertools;
+use pyo3::{pyclass, pymethods, Bound, PyRef, PyResult};
+use vortex::array::ChunkedEncoding;
+
+use crate::arrays::{ArraySubclass, AsArrayRef, PyArray};
+
+/// Concrete class for arrays with `vortex.chunked` encoding.
+#[pyclass(name = "ChunkedArray", module = "vortex", extends=PyArray, frozen)]
+pub(crate) struct PyChunkedArray;
+
+impl ArraySubclass for PyChunkedArray {
+    type Encoding = ChunkedEncoding;
+}
+
+#[pymethods]
+impl PyChunkedArray {
+    pub fn chunks(self_: PyRef<'_, Self>) -> PyResult<Vec<Bound<'_, PyArray>>> {
+        self_
+            .as_array_ref()
+            .chunks()
+            .map(|chunk| PyArray::init(self_.py(), chunk))
+            .try_collect()
+    }
+}

pyvortex/python/vortex/encoding.py

@@ -0,0 +1,21 @@
+use pyo3::{pyclass, pymethods, Bound, PyRef, PyResult};
+use vortex::array::ConstantEncoding;
+
+use crate::arrays::{ArraySubclass, AsArrayRef, PyArray};
+use crate::scalar::PyScalar;
+
+/// Concrete class for arrays with `vortex.constant` encoding.
+#[pyclass(name = "ConstantArray", module = "vortex", extends=PyArray, frozen)]
+pub(crate) struct PyConstantArray;
+
+impl ArraySubclass for PyConstantArray {
+    type Encoding = ConstantEncoding;
+}
+
+#[pymethods]
+impl PyConstantArray {
+    /// Return the scalar value of the constant array.
+    pub fn scalar(self_: PyRef<'_, Self>) -> PyResult<Bound<PyScalar>> {
+        PyScalar::init(self_.py(), self_.as_array_ref().scalar())
+    }
+}