Expose Transforms to Python Binding (#556)

* bucket transform rust binding

* format

* poetry x maturin

* ignore poetry.lock in license check

* update bindings_python_ci to use makefile

* newline

* python-poetry/poetry#9135

* use hatch instead of poetry

* refactor

* revert licenserc change

* adopt review feedback

* comments

* unused dependency

* adopt review comment

* newline

* I like this approach a lot better

* more tests

.github/workflows/bindings_python_ci.yml

@@ -80,4 +80,4 @@ jobs:
           set -e
           pip install hatch==1.12.0
           hatch run dev:pip install dist/pyiceberg_core-*.whl --force-reinstall
-          hatch run dev:test
+          hatch run dev:test

.gitignore

@@ -24,3 +24,5 @@ dist/*
 **/venv
 *.so
 *.pyc
+*.whl
+*.tar.gz

bindings/python/Cargo.toml

@@ -32,4 +32,5 @@ crate-type = ["cdylib"]
 
 [dependencies]
 iceberg = { path = "../../crates/iceberg" }
-pyo3 = { version = "0.22", features = ["extension-module"] }
+pyo3 = { version = "0.21.1", features = ["extension-module"] }
+arrow = { version = "52.2.0", features = ["pyarrow"] }

bindings/python/pyproject.toml

@@ -43,6 +43,7 @@ ignore = ["F403", "F405"]
 dependencies = [
     "maturin>=1.0,<2.0",
     "pytest>=8.3.2",
+    "pyarrow>=17.0.0",
 ]
 
 [tool.hatch.envs.dev.scripts]

bindings/python/src/lib.rs

@@ -17,15 +17,21 @@
 
 use iceberg::io::FileIOBuilder;
 use pyo3::prelude::*;
+use pyo3::wrap_pyfunction;
+
+mod transform;
 
 #[pyfunction]
 fn hello_world() -> PyResult<String> {
     let _ = FileIOBuilder::new_fs_io().build().unwrap();
     Ok("Hello, world!".to_string())
 }
 
+
 #[pymodule]
 fn pyiceberg_core_rust(m: &Bound<'_, PyModule>) -> PyResult<()> {
     m.add_function(wrap_pyfunction!(hello_world, m)?)?;
+
+    m.add_class::<transform::ArrowArrayTransform>()?;
     Ok(())
 }

bindings/python/src/transform.rs

@@ -0,0 +1,87 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+use iceberg::spec::Transform;
+use iceberg::transform::create_transform_function;
+
+use arrow::{
+    array::{make_array, Array, ArrayData},
+};
+use arrow::pyarrow::{FromPyArrow, ToPyArrow};
+use pyo3::{exceptions::PyValueError, prelude::*};
+
+fn to_py_err(err: iceberg::Error) -> PyErr {
+    PyValueError::new_err(err.to_string())
+}
+
+#[pyclass]
+pub struct ArrowArrayTransform {
+}
+
+fn apply(array: PyObject, transform: Transform, py: Python) -> PyResult<PyObject> {
+    // import
+    let array = ArrayData::from_pyarrow_bound(array.bind(py))?;
+    let array = make_array(array);
+    let transform_function = create_transform_function(&transform).map_err(to_py_err)?;
+    let array = transform_function.transform(array).map_err(to_py_err)?;
+    // export
+    let array = array.into_data();
+    array.to_pyarrow(py)
+}
+
+#[pymethods]
+impl ArrowArrayTransform {
+    #[staticmethod]
+    pub fn identity(array: PyObject, py: Python) -> PyResult<PyObject> {
+        apply(array, Transform::Identity, py)
+    }
+
+    #[staticmethod]
+    pub fn void(array: PyObject, py: Python) -> PyResult<PyObject> {
+        apply(array, Transform::Void, py)
+    }
+
+    #[staticmethod]
+    pub fn year(array: PyObject, py: Python) -> PyResult<PyObject> {
+        apply(array, Transform::Year, py)
+    }
+
+    #[staticmethod]
+    pub fn month(array: PyObject, py: Python) -> PyResult<PyObject> {
+        apply(array, Transform::Month, py)
+    }
+
+    #[staticmethod]
+    pub fn day(array: PyObject, py: Python) -> PyResult<PyObject> {
+        apply(array, Transform::Day, py)
+    }
+
+    #[staticmethod]
+    pub fn hour(array: PyObject, py: Python) -> PyResult<PyObject> {
+        apply(array, Transform::Hour, py)
+    }
+
+    #[staticmethod]
+    pub fn bucket(array: PyObject, num_buckets: u32, py: Python) -> PyResult<PyObject> {
+        apply(array, Transform::Bucket(num_buckets), py)
+    }
+
+    #[staticmethod]
+    pub fn truncate(array: PyObject, width: u32, py: Python) -> PyResult<PyObject> {
+        apply(array, Transform::Truncate(width), py)
+    }
+}

bindings/python/tests/test_transform.py

@@ -0,0 +1,91 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+
+from datetime import date, datetime
+
+import pyarrow as pa
+import pytest
+from pyiceberg_core import ArrowArrayTransform
+
+
+def test_identity_transform():
+    arr = pa.array([1, 2])
+    result = ArrowArrayTransform.identity(arr)
+    assert result == arr
+
+
+def test_bucket_transform():
+    arr = pa.array([1, 2])
+    result = ArrowArrayTransform.bucket(arr, 10)
+    expected = pa.array([6, 2], type=pa.int32())
+    assert result == expected
+
+
+def test_bucket_transform_fails_for_list_type_input():
+    arr = pa.array([[1, 2], [3, 4]])
+    with pytest.raises(
+        ValueError,
+        match=r"FeatureUnsupported => Unsupported data type for bucket transform",
+    ):
+        ArrowArrayTransform.bucket(arr, 10)
+
+
+def test_bucket_chunked_array():
+    chunked = pa.chunked_array([pa.array([1, 2]), pa.array([3, 4])])
+    result_chunks = []
+    for arr in chunked.iterchunks():
+        result_chunks.append(ArrowArrayTransform.bucket(arr, 10))
+
+    expected = pa.chunked_array(
+        [pa.array([6, 2], type=pa.int32()), pa.array([5, 0], type=pa.int32())]
+    )
+    assert pa.chunked_array(result_chunks).equals(expected)
+
+
+def test_year_transform():
+    arr = pa.array([date(1970, 1, 1), date(2000, 1, 1)])
+    result = ArrowArrayTransform.year(arr)
+    expected = pa.array([0, 30], type=pa.int32())
+    assert result == expected
+
+
+def test_month_transform():
+    arr = pa.array([date(1970, 1, 1), date(2000, 4, 1)])
+    result = ArrowArrayTransform.month(arr)
+    expected = pa.array([0, 30 * 12 + 3], type=pa.int32())
+    assert result == expected
+
+
+def test_day_transform():
+    arr = pa.array([date(1970, 1, 1), date(2000, 4, 1)])
+    result = ArrowArrayTransform.day(arr)
+    expected = pa.array([0, 11048], type=pa.int32())
+    assert result == expected
+
+
+def test_hour_transform():
+    arr = pa.array([datetime(1970, 1, 1, 19, 1, 23), datetime(2000, 3, 1, 12, 1, 23)])
+    result = ArrowArrayTransform.hour(arr)
+    expected = pa.array([19, 264420], type=pa.int32())
+    assert result == expected
+
+
+def test_truncate_transform():
+    arr = pa.array(["this is a long string", "hi my name is sung"])
+    result = ArrowArrayTransform.truncate(arr, 5)
+    expected = pa.array(["this ", "hi my"])
+    assert result == expected