pyo3/conversions/
indexmap.rs

1#![cfg(feature = "indexmap")]
2
3//!  Conversions to and from [indexmap](https://docs.rs/indexmap/)’s
4//! `IndexMap`.
5//!
6//! [`indexmap::IndexMap`] is a hash table that is closely compatible with the standard [`std::collections::HashMap`],
7//! with the difference that it preserves the insertion order when iterating over keys. It was inspired
8//! by Python's 3.6+ dict implementation.
9//!
10//! Dictionary order is guaranteed to be insertion order in Python, hence IndexMap is a good candidate
11//! for maintaining an equivalent behaviour in Rust.
12//!
13//! # Setup
14//!
15//! To use this feature, add this to your **`Cargo.toml`**:
16//!
17//! ```toml
18//! [dependencies]
19//! # change * to the latest versions
20//! indexmap = "*"
21#![doc = concat!("pyo3 = { version = \"", env!("CARGO_PKG_VERSION"),  "\", features = [\"indexmap\"] }")]
22//! ```
23//!
24//! Note that you must use compatible versions of indexmap and PyO3.
25//! The required indexmap version may vary based on the version of PyO3.
26//!
27//! # Examples
28//!
29//! Using [indexmap](https://docs.rs/indexmap) to return a dictionary with some statistics
30//! about a list of numbers. Because of the insertion order guarantees, the Python code will
31//! always print the same result, matching users' expectations about Python's dict.
32//! ```rust
33//! use indexmap::{indexmap, IndexMap};
34//! use pyo3::prelude::*;
35//!
36//! fn median(data: &Vec<i32>) -> f32 {
37//!     let sorted_data = data.clone().sort();
38//!     let mid = data.len() / 2;
39//!     if data.len() % 2 == 0 {
40//!         data[mid] as f32
41//!     }
42//!     else {
43//!         (data[mid] + data[mid - 1]) as f32 / 2.0
44//!     }
45//! }
46//!
47//! fn mean(data: &Vec<i32>) -> f32 {
48//!     data.iter().sum::<i32>() as f32 / data.len() as f32
49//! }
50//! fn mode(data: &Vec<i32>) -> f32 {
51//!     let mut frequency = IndexMap::new(); // we can use IndexMap as any hash table
52//!
53//!     for &element in data {
54//!         *frequency.entry(element).or_insert(0) += 1;
55//!     }
56//!
57//!     frequency
58//!         .iter()
59//!         .max_by(|a, b| a.1.cmp(&b.1))
60//!         .map(|(k, _v)| *k)
61//!         .unwrap() as f32
62//!   }
63//!
64//! #[pyfunction]
65//! fn calculate_statistics(data: Vec<i32>) -> IndexMap<&'static str, f32> {
66//!     indexmap! {
67//!        "median" => median(&data),
68//!        "mean" => mean(&data),
69//!        "mode" => mode(&data),
70//!     }
71//! }
72//!
73//! #[pymodule]
74//! fn my_module(m: &Bound<'_, PyModule>) -> PyResult<()> {
75//!     m.add_function(wrap_pyfunction!(calculate_statistics, m)?)?;
76//!     Ok(())
77//! }
78//! ```
79//!
80//! Python code:
81//! ```python
82//! from my_module import calculate_statistics
83//!
84//! data = [1, 1, 1, 3, 4, 5]
85//! print(calculate_statistics(data))
86//! # always prints {"median": 2.0, "mean": 2.5, "mode": 1.0} in the same order
87//! # if another hash table was used, the order could be random
88//! ```
89
90use crate::conversion::IntoPyObject;
91use crate::types::*;
92use crate::{Bound, FromPyObject, PyErr, PyObject, Python};
93#[allow(deprecated)]
94use crate::{IntoPy, ToPyObject};
95use std::{cmp, hash};
96
97#[allow(deprecated)]
98impl<K, V, H> ToPyObject for indexmap::IndexMap<K, V, H>
99where
100    K: hash::Hash + cmp::Eq + ToPyObject,
101    V: ToPyObject,
102    H: hash::BuildHasher,
103{
104    fn to_object(&self, py: Python<'_>) -> PyObject {
105        let dict = PyDict::new(py);
106        for (k, v) in self {
107            dict.set_item(k.to_object(py), v.to_object(py)).unwrap();
108        }
109        dict.into_any().unbind()
110    }
111}
112
113#[allow(deprecated)]
114impl<K, V, H> IntoPy<PyObject> for indexmap::IndexMap<K, V, H>
115where
116    K: hash::Hash + cmp::Eq + IntoPy<PyObject>,
117    V: IntoPy<PyObject>,
118    H: hash::BuildHasher,
119{
120    fn into_py(self, py: Python<'_>) -> PyObject {
121        let dict = PyDict::new(py);
122        for (k, v) in self {
123            dict.set_item(k.into_py(py), v.into_py(py)).unwrap();
124        }
125        dict.into_any().unbind()
126    }
127}
128
129impl<'py, K, V, H> IntoPyObject<'py> for indexmap::IndexMap<K, V, H>
130where
131    K: IntoPyObject<'py> + cmp::Eq + hash::Hash,
132    V: IntoPyObject<'py>,
133    H: hash::BuildHasher,
134{
135    type Target = PyDict;
136    type Output = Bound<'py, Self::Target>;
137    type Error = PyErr;
138
139    fn into_pyobject(self, py: Python<'py>) -> Result<Self::Output, Self::Error> {
140        let dict = PyDict::new(py);
141        for (k, v) in self {
142            dict.set_item(k, v)?;
143        }
144        Ok(dict)
145    }
146}
147
148impl<'a, 'py, K, V, H> IntoPyObject<'py> for &'a indexmap::IndexMap<K, V, H>
149where
150    &'a K: IntoPyObject<'py> + cmp::Eq + hash::Hash,
151    &'a V: IntoPyObject<'py>,
152    H: hash::BuildHasher,
153{
154    type Target = PyDict;
155    type Output = Bound<'py, Self::Target>;
156    type Error = PyErr;
157
158    fn into_pyobject(self, py: Python<'py>) -> Result<Self::Output, Self::Error> {
159        let dict = PyDict::new(py);
160        for (k, v) in self {
161            dict.set_item(k, v)?;
162        }
163        Ok(dict)
164    }
165}
166
167impl<'py, K, V, S> FromPyObject<'py> for indexmap::IndexMap<K, V, S>
168where
169    K: FromPyObject<'py> + cmp::Eq + hash::Hash,
170    V: FromPyObject<'py>,
171    S: hash::BuildHasher + Default,
172{
173    fn extract_bound(ob: &Bound<'py, PyAny>) -> Result<Self, PyErr> {
174        let dict = ob.downcast::<PyDict>()?;
175        let mut ret = indexmap::IndexMap::with_capacity_and_hasher(dict.len(), S::default());
176        for (k, v) in dict {
177            ret.insert(k.extract()?, v.extract()?);
178        }
179        Ok(ret)
180    }
181}
182
183#[cfg(test)]
184mod test_indexmap {
185
186    use crate::types::*;
187    use crate::{IntoPyObject, Python};
188
189    #[test]
190    fn test_indexmap_indexmap_into_pyobject() {
191        Python::with_gil(|py| {
192            let mut map = indexmap::IndexMap::<i32, i32>::new();
193            map.insert(1, 1);
194
195            let py_map = (&map).into_pyobject(py).unwrap();
196
197            assert!(py_map.len() == 1);
198            assert!(
199                py_map
200                    .get_item(1)
201                    .unwrap()
202                    .unwrap()
203                    .extract::<i32>()
204                    .unwrap()
205                    == 1
206            );
207            assert_eq!(
208                map,
209                py_map.extract::<indexmap::IndexMap::<i32, i32>>().unwrap()
210            );
211        });
212    }
213
214    #[test]
215    fn test_indexmap_indexmap_into_dict() {
216        Python::with_gil(|py| {
217            let mut map = indexmap::IndexMap::<i32, i32>::new();
218            map.insert(1, 1);
219
220            let py_map = map.into_py_dict(py).unwrap();
221
222            assert_eq!(py_map.len(), 1);
223            assert_eq!(
224                py_map
225                    .get_item(1)
226                    .unwrap()
227                    .unwrap()
228                    .extract::<i32>()
229                    .unwrap(),
230                1
231            );
232        });
233    }
234
235    #[test]
236    fn test_indexmap_indexmap_insertion_order_round_trip() {
237        Python::with_gil(|py| {
238            let n = 20;
239            let mut map = indexmap::IndexMap::<i32, i32>::new();
240
241            for i in 1..=n {
242                if i % 2 == 1 {
243                    map.insert(i, i);
244                } else {
245                    map.insert(n - i, i);
246                }
247            }
248
249            let py_map = (&map).into_py_dict(py).unwrap();
250
251            let trip_map = py_map.extract::<indexmap::IndexMap<i32, i32>>().unwrap();
252
253            for (((k1, v1), (k2, v2)), (k3, v3)) in
254                map.iter().zip(py_map.iter()).zip(trip_map.iter())
255            {
256                let k2 = k2.extract::<i32>().unwrap();
257                let v2 = v2.extract::<i32>().unwrap();
258                assert_eq!((k1, v1), (&k2, &v2));
259                assert_eq!((k1, v1), (k3, v3));
260                assert_eq!((&k2, &v2), (k3, v3));
261            }
262        });
263    }
264}
pyo3/conversions/indexmap.rs

pyo3/conversions/
indexmap.rs
