plotters/coord/ranged1d/combinators/
group_by.rs

1use crate::coord::ranged1d::{
2    AsRangedCoord, DiscreteRanged, KeyPointHint, NoDefaultFormatting, Ranged, ValueFormatter,
3};
4use std::ops::Range;
5
6/// Grouping the value in the coordinate specification.
7///
8/// This combinator doesn't change the coordinate mapping behavior. But it changes how
9/// the key point is generated, this coordinate specification will enforce that only the first value in each group
10/// can be emitted as the bold key points.
11///
12/// This is useful, for example, when we have an X axis is a integer and denotes days.
13/// And we are expecting the tick mark denotes weeks, in this way we can make the range
14/// spec grouping by 7 elements.
15/// With the help of the GroupBy decorator, this can be archived quite easily:
16///```rust
17///use plotters::prelude::*;
18///let mut buf = vec![0;1024*768*3];
19///let area = BitMapBackend::with_buffer(buf.as_mut(), (1024, 768)).into_drawing_area();
20///let chart = ChartBuilder::on(&area)
21///    .build_cartesian_2d((0..100).group_by(7), 0..100)
22///    .unwrap();
23///```
24///
25/// To apply this combinator, call [ToGroupByRange::group_by](trait.ToGroupByRange.html#tymethod.group_by) method on any discrete coordinate spec.
26#[derive(Clone)]
27pub struct GroupBy<T: DiscreteRanged>(T, usize);
28
29/// The trait that provides method `Self::group_by` function which creates a
30/// `GroupBy` decorated ranged value.
31pub trait ToGroupByRange: AsRangedCoord + Sized
32where
33    Self::CoordDescType: DiscreteRanged,
34{
35    /// Make a grouping ranged value, see the documentation for `GroupBy` for details.
36    ///
37    /// - `value`: The number of values we want to group it
38    /// - **return**: The newly created grouping range specification
39    fn group_by(self, value: usize) -> GroupBy<<Self as AsRangedCoord>::CoordDescType> {
40        GroupBy(self.into(), value)
41    }
42}
43
44impl<T: AsRangedCoord + Sized> ToGroupByRange for T where T::CoordDescType: DiscreteRanged {}
45
46impl<T: DiscreteRanged> DiscreteRanged for GroupBy<T> {
47    fn size(&self) -> usize {
48        (self.0.size() + self.1 - 1) / self.1
49    }
50    fn index_of(&self, value: &Self::ValueType) -> Option<usize> {
51        self.0.index_of(value).map(|idx| idx / self.1)
52    }
53    fn from_index(&self, index: usize) -> Option<Self::ValueType> {
54        self.0.from_index(index * self.1)
55    }
56}
57
58impl<T, R: DiscreteRanged<ValueType = T> + ValueFormatter<T>> ValueFormatter<T> for GroupBy<R> {
59    fn format(value: &T) -> String {
60        R::format(value)
61    }
62}
63
64impl<T: DiscreteRanged> Ranged for GroupBy<T> {
65    type FormatOption = NoDefaultFormatting;
66    type ValueType = T::ValueType;
67    fn map(&self, value: &T::ValueType, limit: (i32, i32)) -> i32 {
68        self.0.map(value, limit)
69    }
70    fn range(&self) -> Range<T::ValueType> {
71        self.0.range()
72    }
73    // TODO: See issue issue #88
74    fn key_points<HintType: KeyPointHint>(&self, hint: HintType) -> Vec<T::ValueType> {
75        let range = 0..(self.0.size() + self.1) / self.1;
76        //let logic_range: RangedCoordusize = range.into();
77
78        let interval =
79            ((range.end - range.start + hint.bold_points() - 1) / hint.bold_points()).max(1);
80        let count = (range.end - range.start) / interval;
81
82        let idx_iter = (0..hint.bold_points()).map(|x| x * interval);
83
84        if hint.weight().allow_light_points() && count < hint.bold_points() * 2 {
85            let outer_ticks = idx_iter;
86            let outer_tick_size = interval * self.1;
87            let inner_ticks_per_group = hint.max_num_points() / outer_ticks.len();
88            let inner_ticks = (outer_tick_size + inner_ticks_per_group - 1) / inner_ticks_per_group;
89            let inner_ticks: Vec<_> = (0..(outer_tick_size / inner_ticks))
90                .map(move |x| x * inner_ticks)
91                .collect();
92            let size = self.0.size();
93            return outer_ticks
94                .flat_map(|base| inner_ticks.iter().map(move |&ofs| base * self.1 + ofs))
95                .take_while(|&idx| idx < size)
96                .map(|x| self.0.from_index(x).unwrap())
97                .collect();
98        }
99
100        idx_iter
101            .map(|x| self.0.from_index(x * self.1).unwrap())
102            .collect()
103    }
104}
105
106#[cfg(test)]
107mod test {
108    use super::*;
109    #[test]
110    fn test_group_by() {
111        let coord = (0..100).group_by(10);
112        assert_eq!(coord.size(), 11);
113        for (idx, val) in (0..).zip(coord.values()) {
114            assert_eq!(val, idx * 10);
115            assert_eq!(coord.from_index(idx as usize), Some(val));
116        }
117    }
118}
plotters/coord/ranged1d/combinators/group_by.rs

plotters/coord/ranged1d/combinators/
group_by.rs
