vortex_mask/
intersect_by_rank.rs

1// SPDX-License-Identifier: Apache-2.0
2// SPDX-FileCopyrightText: Copyright the Vortex contributors
3
4use crate::{AllOr, Mask};
5
6impl Mask {
7    /// Take the intersection of the `mask` with the set of true values in `self`.
8    ///
9    /// We are more interested in low selectivity `self` (as indices) with a boolean buffer mask,
10    /// so we don't optimize for other cases, yet.
11    ///
12    /// Note: we might be able to accelerate this function on x86 with BMI, see:
13    /// <https://www.microsoft.com/en-us/research/uploads/prod/2023/06/parquet-select-sigmod23.pdf>
14    ///
15    /// # Examples
16    ///
17    /// Keep the third and fifth set values from mask `m1`:
18    /// ```
19    /// use vortex_mask::Mask;
20    ///
21    /// let m1 = Mask::from_iter([true, false, false, true, true, true, false, true]);
22    /// let m2 = Mask::from_iter([false, false, true, false, true]);
23    /// assert_eq!(
24    ///     m1.intersect_by_rank(&m2),
25    ///     Mask::from_iter([false, false, false, false, true, false, false, true])
26    /// );
27    /// ```
28    pub fn intersect_by_rank(&self, mask: &Mask) -> Mask {
29        assert_eq!(self.true_count(), mask.len());
30
31        match (self.indices(), mask.indices()) {
32            (AllOr::All, _) => mask.clone(),
33            (_, AllOr::All) => self.clone(),
34            (AllOr::None, _) => Self::new_false(0),
35            (_, AllOr::None) => Self::new_false(self.len()),
36            (AllOr::Some(self_indices), AllOr::Some(mask_indices)) => {
37                Self::from_indices(
38                    self.len(),
39                    mask_indices
40                        .iter()
41                        .map(|idx|
42                            // This is verified as safe because we know that the indices are less than the
43                            // mask.len() and we known mask.len() <= self.len(),
44                            // implied by `self.true_count() == mask.len()`.
45                            unsafe{*self_indices.get_unchecked(*idx)})
46                        .collect(),
47                )
48            }
49        }
50    }
51}
52
53#[cfg(test)]
54mod test {
55    use arrow_buffer::BooleanBuffer;
56    use rstest::rstest;
57
58    use crate::Mask;
59
60    #[test]
61    fn mask_bitand_all_as_bit_and() {
62        let this = Mask::from_buffer(BooleanBuffer::from_iter(vec![true, true, true, true, true]));
63        let mask = Mask::from_buffer(BooleanBuffer::from_iter(vec![
64            false, true, false, true, true,
65        ]));
66        assert_eq!(
67            this.intersect_by_rank(&mask),
68            Mask::from_indices(5, vec![1, 3, 4])
69        );
70    }
71
72    #[test]
73    fn mask_bitand_all_true() {
74        let this = Mask::from_buffer(BooleanBuffer::from_iter(vec![
75            false, false, true, true, true,
76        ]));
77        let mask = Mask::from_buffer(BooleanBuffer::from_iter(vec![true, true, true]));
78        assert_eq!(
79            this.intersect_by_rank(&mask),
80            Mask::from_indices(5, vec![2, 3, 4])
81        );
82    }
83
84    #[test]
85    fn mask_bitand_true() {
86        let this = Mask::from_buffer(BooleanBuffer::from_iter(vec![
87            true, false, false, true, true,
88        ]));
89        let mask = Mask::from_buffer(BooleanBuffer::from_iter(vec![true, false, true]));
90        assert_eq!(
91            this.intersect_by_rank(&mask),
92            Mask::from_indices(5, vec![0, 4])
93        );
94    }
95
96    #[test]
97    fn mask_bitand_false() {
98        let this = Mask::from_buffer(BooleanBuffer::from_iter(vec![
99            true, false, false, true, true,
100        ]));
101        let mask = Mask::from_buffer(BooleanBuffer::from_iter(vec![false, false, false]));
102        assert_eq!(this.intersect_by_rank(&mask), Mask::from_indices(5, vec![]));
103    }
104
105    #[rstest]
106    #[case::all_true_with_all_true(
107        Mask::new_true(5),
108        Mask::new_true(5),
109        vec![0, 1, 2, 3, 4]
110    )]
111    #[case::all_true_with_all_false(
112        Mask::new_true(5),
113        Mask::new_false(5),
114        vec![]
115    )]
116    #[case::all_false_with_any(
117        Mask::new_false(10),
118        Mask::new_true(0),
119        vec![]
120    )]
121    #[case::indices_with_all_true(
122        Mask::from_indices(10, vec![2, 5, 7, 9]),
123        Mask::new_true(4),
124        vec![2, 5, 7, 9]
125    )]
126    #[case::indices_with_all_false(
127        Mask::from_indices(10, vec![2, 5, 7, 9]),
128        Mask::new_false(4),
129        vec![]
130    )]
131    fn test_intersect_by_rank_special_cases(
132        #[case] base_mask: Mask,
133        #[case] rank_mask: Mask,
134        #[case] expected_indices: Vec<usize>,
135    ) {
136        let result = base_mask.intersect_by_rank(&rank_mask);
137
138        match result.indices() {
139            crate::AllOr::All => assert_eq!(expected_indices.len(), result.len()),
140            crate::AllOr::None => assert!(expected_indices.is_empty()),
141            crate::AllOr::Some(indices) => assert_eq!(indices, &expected_indices[..]),
142        }
143    }
144
145    #[test]
146    fn test_intersect_by_rank_example() {
147        // Example from the documentation
148        let m1 = Mask::from_iter([true, false, false, true, true, true, false, true]);
149        let m2 = Mask::from_iter([false, false, true, false, true]);
150        let result = m1.intersect_by_rank(&m2);
151        let expected = Mask::from_iter([false, false, false, false, true, false, false, true]);
152        assert_eq!(result, expected);
153    }
154
155    #[test]
156    #[should_panic]
157    fn test_intersect_by_rank_wrong_length() {
158        let m1 = Mask::from_indices(10, vec![2, 5, 7]); // 3 true values
159        let m2 = Mask::new_true(5); // 5 true values - doesn't match
160        let _ = m1.intersect_by_rank(&m2);
161    }
162
163    #[rstest]
164    #[case::single_element(
165        vec![3],
166        vec![true],
167        vec![3]
168    )]
169    #[case::single_element_masked(
170        vec![3],
171        vec![false],
172        vec![]
173    )]
174    #[case::alternating(
175        vec![0, 2, 4, 6, 8],
176        vec![true, false, true, false, true],
177        vec![0, 4, 8]
178    )]
179    #[case::consecutive(
180        vec![5, 6, 7, 8, 9],
181        vec![false, true, true, true, false],
182        vec![6, 7, 8]
183    )]
184    fn test_intersect_by_rank_patterns(
185        #[case] base_indices: Vec<usize>,
186        #[case] rank_pattern: Vec<bool>,
187        #[case] expected_indices: Vec<usize>,
188    ) {
189        let base = Mask::from_indices(10, base_indices);
190        let rank = Mask::from_iter(rank_pattern);
191        let result = base.intersect_by_rank(&rank);
192
193        match result.indices() {
194            crate::AllOr::Some(indices) => assert_eq!(indices, &expected_indices[..]),
195            crate::AllOr::None => assert!(expected_indices.is_empty()),
196            _ => panic!("Unexpected result"),
197        }
198    }
199}
vortex_mask/intersect_by_rank.rs

vortex_mask/
intersect_by_rank.rs
