Copy-edit the examples for consistency

.github/workflows/ci.yml

@@ -77,7 +77,7 @@ jobs:
       - name: Test example
         run: |
           pip install nox
-          nox -f examples/simple-extension/noxfile.py
+          nox -f examples/simple/noxfile.py
     env:
       CARGO_TERM_VERBOSE: true
       CARGO_BUILD_TARGET: ${{ matrix.platform.rust-target }}
@@ -99,7 +99,7 @@ jobs:
           default: true
       - uses: Swatinem/rust-cache@v1
         with:
-          working-directory: examples/simple-extension
+          working-directory: examples/simple
         continue-on-error: true
       - name: Install toml
         run: pip install toml
@@ -112,11 +112,11 @@ jobs:
           cargo_toml["workspace"] = {}
           with open("Cargo.toml", "w") as f:
             toml.dump(cargo_toml, f)
-        working-directory: examples/simple-extension
+        working-directory: examples/simple
         shell: python
       - name: Generate lockfile
         run: cargo generate-lockfile
-        working-directory: examples/simple-extension
+        working-directory: examples/simple
       - name: Unify dependencies on ndarray to 0.13.1
         run: |
           import toml
@@ -126,12 +126,12 @@ jobs:
             if pkg["name"] == "ndarray" and pkg["version"] != "0.13.1":
               pkg_id = pkg["name"] + ":" + pkg["version"]
               subprocess.run(["cargo", "update", "--package", pkg_id, "--precise", "0.13.1"], check=True)
-        working-directory: examples/simple-extension
+        working-directory: examples/simple
         shell: python
       - name: Test example
         run: |
           pip install nox
-          nox -f examples/simple-extension/noxfile.py
+          nox -f examples/simple/noxfile.py
 
   examples:
     runs-on: ubuntu-latest

README.md

@@ -28,10 +28,9 @@ Rust bindings for the NumPy C-API.
 
 ### Write a Python module in Rust
 
-Please see the [simple-extension](https://github.com/PyO3/rust-numpy/tree/main/examples/simple-extension)
-directory for the complete example.
+Please see the [simple](examples/simple) example for how to get started.
 
-Also, we have an example project with [ndarray-linalg](https://github.com/PyO3/rust-numpy/tree/main/examples/linalg).
+There are also examples using [ndarray-linalg](examples/linalg) and [rayon](examples/parallel).
 
 ```toml
 [lib]
@@ -46,22 +45,23 @@ numpy = "0.15"
 ```rust
 use numpy::ndarray::{ArrayD, ArrayViewD, ArrayViewMutD};
 use numpy::{IntoPyArray, PyArrayDyn, PyReadonlyArrayDyn};
-use pyo3::prelude::{pymodule, PyModule, PyResult, Python};
+use pyo3::{pymodule, types::PyModule, PyResult, Python};
 
 #[pymodule]
 fn rust_ext(_py: Python<'_>, m: &PyModule) -> PyResult<()> {
-    // immutable example
+    // example using immutable borrows producing a new array
     fn axpy(a: f64, x: ArrayViewD<'_, f64>, y: ArrayViewD<'_, f64>) -> ArrayD<f64> {
         a * &x + &y
     }
 
-    // mutable example (no return)
+    // example using a mutable borrow to modify an array in-place
     fn mult(a: f64, mut x: ArrayViewMutD<'_, f64>) {
         x *= a;
     }
 
     // wrapper of `axpy`
-    #[pyfn(m, "axpy")]
+    #[pyfn(m)]
+    #[pyo3(name = "axpy")]
     fn axpy_py<'py>(
         py: Python<'py>,
         a: f64,
@@ -74,7 +74,8 @@ fn rust_ext(_py: Python<'_>, m: &PyModule) -> PyResult<()> {
     }
 
     // wrapper of `mult`
-    #[pyfn(m, "mult")]
+    #[pyfn(m)]
+    #[pyo3(name = "mult")]
     fn mult_py(_py: Python<'_>, a: f64, x: &PyArrayDyn<f64>) -> PyResult<()> {
         let x = unsafe { x.as_array_mut() };
         mult(a, x);
@@ -98,23 +99,24 @@ numpy = "0.15"
 
 ```rust
 use numpy::PyArray1;
-use pyo3::prelude::{PyResult, Python};
-use pyo3::types::IntoPyDict;
+use pyo3::{types::IntoPyDict, PyResult, Python};
 
 fn main() -> PyResult<()> {
     Python::with_gil(|py| {
         let np = py.import("numpy")?;
         let locals = [("np", np)].into_py_dict(py);
+
         let pyarray: &PyArray1<i32> = py
             .eval("np.absolute(np.array([-1, -2, -3], dtype='int32'))", Some(locals), None)?
             .extract()?;
+
         let readonly = pyarray.readonly();
         let slice = readonly.as_slice()?;
         assert_eq!(slice, &[1, 2, 3]);
+
         Ok(())
     })
 }
-
 ```
 
 ## Dependency on ndarray
@@ -150,5 +152,6 @@ and [pull requests](https://github.com/PyO3/rust-numpy/pulls).
 
 PyO3's [Contributing.md](https://github.com/PyO3/pyo3/blob/main/Contributing.md)
 is a nice guide for starting.
+
 Also, we have a [Gitter](https://gitter.im/PyO3/Lobby) channel for communicating.
 

examples/linalg/Cargo.toml

@@ -1,5 +1,5 @@
 [package]
-name = "numpy-linalg-example"
+name = "rust-linalg"
 version = "0.1.0"
 authors = ["Yuji Kanagawa <[email protected]>"]
 edition = "2018"

examples/linalg/README.md

@@ -1,8 +1,7 @@
-# rust-numpy example extension with linalg
+# rust-numpy extension using ndarray-linalg
 
-An example extension with [ndarray-linalg](https://github.com/rust-ndarray/ndarray-linalg).
+An example extension using [ndarray-linalg](https://github.com/rust-ndarray/ndarray-linalg).
 
 Will link against a system-provided OpenBLAS.
 
-See [simple-extension's README](https://github.com/PyO3/rust-numpy/blob/main/examples/simple-extension/README.md)
-for an introduction.
+See the [README](../simple/README.md) of the simple extension for more information.

examples/linalg/noxfile.py

@@ -3,6 +3,6 @@
 
 @nox.session
 def tests(session):
-    session.install('pip', 'numpy', 'pytest')
-    session.run('pip', 'install', '.', '-v')
-    session.run('pytest')
+    session.install("pip", "numpy", "pytest")
+    session.run("pip", "install", ".", "-v")
+    session.run("pytest")

examples/linalg/src/lib.rs

@@ -1,6 +1,6 @@
 use ndarray_linalg::solve::Inverse;
 use numpy::{IntoPyArray, PyArray2, PyReadonlyArray2};
-use pyo3::{exceptions::PyRuntimeError, pymodule, types::PyModule, PyErr, PyResult, Python};
+use pyo3::{exceptions::PyRuntimeError, pymodule, types::PyModule, PyResult, Python};
 
 #[pymodule]
 fn rust_linalg(_py: Python<'_>, m: &PyModule) -> PyResult<()> {
@@ -9,7 +9,7 @@ fn rust_linalg(_py: Python<'_>, m: &PyModule) -> PyResult<()> {
         let x = x.as_array();
         let y = x
             .inv()
-            .map_err(|e| PyErr::new::<PyRuntimeError, _>(format!("[rust_linalg] {}", e)))?;
+            .map_err(|e| PyRuntimeError::new_err(e.to_string()))?;
         Ok(y.into_pyarray(py))
     }
     Ok(())

examples/linalg/tests/test_linalg.py

@@ -3,9 +3,12 @@
 
 
 def test_inv():
-    x = np.array([
-        [1, 0],
-        [0, 2],
-    ], dtype=np.float64)
+    x = np.array(
+        [
+            [1, 0],
+            [0, 2],
+        ],
+        dtype=np.float64,
+    )
     y = rust_linalg.inv(x)
     np.testing.assert_array_almost_equal(y, np.linalg.inv(x))

examples/parallel/Cargo.toml

@@ -1,5 +1,5 @@
 [package]
-name = "numpy-parallel-example"
+name = "rust-parallel"
 version = "0.1.0"
 authors = ["Yuji Kanagawa <[email protected]>"]
 edition = "2018"

examples/parallel/README.md

@@ -1,7 +1,5 @@
-# rust-numpy example extension using optional ndarray features
+# rust-numpy extension using optional ndarray features
 
-An example extension using [optional ndarray features](https://docs.rs/ndarray/latest/ndarray/doc/crate_feature_flags/index.html), parallel execution using Rayon and optimized kernels using BLAS in this case.
-
-See [simple-extension's README](https://github.com/PyO3/rust-numpy/blob/main/examples/simple-extension/README.md)
-for an introduction.
+An example extension using [optional ndarray features](https://docs.rs/ndarray/latest/ndarray/doc/crate_feature_flags/index.html), in this case parallel execution using Rayon and optimized kernels using BLAS.
 
+See the [README](../simple/README.md) of the simple extension for more information.

examples/parallel/noxfile.py

@@ -3,6 +3,6 @@
 
 @nox.session
 def tests(session):
-    session.install('pip', 'numpy', 'pytest')
-    session.run('pip', 'install', '.', '-v')
-    session.run('pytest')
+    session.install("pip", "numpy", "pytest")
+    session.run("pip", "install", ".", "-v")
+    session.run("pytest")

examples/parallel/src/lib.rs

@@ -1,7 +1,7 @@
 // We need to link `blas_src` directly, c.f. https://github.com/rust-ndarray/ndarray#how-to-enable-blas-integration
 extern crate blas_src;
 
-use ndarray::Zip;
+use numpy::ndarray::Zip;
 use numpy::{IntoPyArray, PyArray1, PyReadonlyArray1, PyReadonlyArray2};
 use pyo3::{pymodule, types::PyModule, PyResult, Python};
 

examples/simple-extension/Cargo.toml → examples/simple/Cargo.toml

@@ -1,5 +1,5 @@
 [package]
-name = "numpy-example"
+name = "rust-ext"
 version = "0.1.0"
 authors = ["Toshiki Teramura <[email protected]>", "Yuji Kanagawa <[email protected]>"]
 edition = "2018"

examples/simple/README.md

@@ -0,0 +1,25 @@
+# simple extension
+
+Here, we use [`maturin`][maturin] for building Python wheels and
+[`nox`][nox] for managing Python dependencies and virtualenvs.
+
+Running `nox` inside this directory creates a virtualenv,
+installs Python dependencies and the extension into it
+and executes the tests from `tests/test_exp.py`.
+
+By running
+```bash
+maturin develop
+```
+from inside a virtualenv, you can use the extension from
+the Python REPL:
+
+```python
+>>> import numpy as np
+>>> import rust_ext
+>>> rust_ext.axpy(2.0, np.array([0.0, 1.0]), np.array([2.0, 3.0]))
+array([2., 5.])
+```
+
+[maturin]: https://github.com/PyO3/maturin
+[nox]: https://github.com/theacodes/nox

examples/simple/noxfile.py

@@ -0,0 +1,8 @@
+import nox
+
+
+@nox.session
+def tests(session):
+    session.install("pip", "numpy", "pytest")
+    session.run("pip", "install", ".", "-v")
+    session.run("pytest")

examples/simple-extension/src/lib.rs → examples/simple/src/lib.rs

@@ -8,17 +8,17 @@ use pyo3::{
 
 #[pymodule]
 fn rust_ext(_py: Python<'_>, m: &PyModule) -> PyResult<()> {
-    // immutable example
+    // example using immutable borrows producing a new array
     fn axpy(a: f64, x: ArrayViewD<'_, f64>, y: ArrayViewD<'_, f64>) -> ArrayD<f64> {
         a * &x + &y
     }
 
-    // mutable example (no return)
+    // example using a mutable borrow to modify an array in-place
     fn mult(a: f64, mut x: ArrayViewMutD<'_, f64>) {
         x *= a;
     }
 
-    // complex example
+    // example using complex numbers
     fn conj(x: ArrayViewD<'_, Complex64>) -> ArrayD<Complex64> {
         x.map(|c| c.conj())
     }
@@ -56,8 +56,8 @@ fn rust_ext(_py: Python<'_>, m: &PyModule) -> PyResult<()> {
         conj(x.as_array()).into_pyarray(py)
     }
 
+    // example of how to extract an array from a dictionary
     #[pyfn(m)]
-    #[pyo3(name = "extract")]
     fn extract(d: &PyDict) -> f64 {
         let x = d
             .get_item("x")

examples/simple-extension/tests/test_ext.py → examples/simple/tests/test_ext.py

@@ -7,10 +7,6 @@ def test_axpy():
     y = np.array([3.0, 3.0, 3.0])
     z = axpy(3.0, x, y)
     np.testing.assert_array_almost_equal(z, np.array([6.0, 9.0, 12.0]))
-    x = np.array([1.0, 2.0, 3.0, 4.0])
-    y = np.array([3.0, 3.0, 3.0, 3.0])
-    z = axpy(3.0, x, y)
-    np.testing.assert_array_almost_equal(z, np.array([6.0, 9.0, 12.0, 15.0]))
 
 
 def test_mult():
@@ -26,5 +22,5 @@ def test_conj():
 
 def test_extract():
     x = np.arange(5.0)
-    d = { "x": x }
+    d = {"x": x}
     np.testing.assert_almost_equal(extract(d), 10.0)