plotters/data/
quartiles.rs

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1/// The quartiles
2#[derive(Clone, Debug)]
3pub struct Quartiles {
4    lower_fence: f64,
5    lower: f64,
6    median: f64,
7    upper: f64,
8    upper_fence: f64,
9}
10
11impl Quartiles {
12    // Extract a value representing the `pct` percentile of a
13    // sorted `s`, using linear interpolation.
14    fn percentile_of_sorted<T: Into<f64> + Copy>(s: &[T], pct: f64) -> f64 {
15        assert!(!s.is_empty());
16        if s.len() == 1 {
17            return s[0].into();
18        }
19        assert!(0_f64 <= pct);
20        let hundred = 100_f64;
21        assert!(pct <= hundred);
22        if (pct - hundred).abs() < std::f64::EPSILON {
23            return s[s.len() - 1].into();
24        }
25        let length = (s.len() - 1) as f64;
26        let rank = (pct / hundred) * length;
27        let lower_rank = rank.floor();
28        let d = rank - lower_rank;
29        let n = lower_rank as usize;
30        let lo = s[n].into();
31        let hi = s[n + 1].into();
32        lo + (hi - lo) * d
33    }
34
35    /// Create a new quartiles struct with the values calculated from the argument.
36    ///
37    /// - `s`: The array of the original values
38    /// - **returns** The newly created quartiles
39    ///
40    /// ```rust
41    /// use plotters::prelude::*;
42    ///
43    /// let quartiles = Quartiles::new(&[7, 15, 36, 39, 40, 41]);
44    /// assert_eq!(quartiles.median(), 37.5);
45    /// ```
46    pub fn new<T: Into<f64> + Copy + PartialOrd>(s: &[T]) -> Self {
47        let mut s = s.to_owned();
48        s.sort_unstable_by(|a, b| a.partial_cmp(b).unwrap());
49
50        let lower = Quartiles::percentile_of_sorted(&s, 25_f64);
51        let median = Quartiles::percentile_of_sorted(&s, 50_f64);
52        let upper = Quartiles::percentile_of_sorted(&s, 75_f64);
53        let iqr = upper - lower;
54        let lower_fence = lower - 1.5 * iqr;
55        let upper_fence = upper + 1.5 * iqr;
56        Self {
57            lower_fence,
58            lower,
59            median,
60            upper,
61            upper_fence,
62        }
63    }
64
65    /// Get the quartiles values.
66    ///
67    /// - **returns** The array [lower fence, lower quartile, median, upper quartile, upper fence]
68    ///
69    /// ```rust
70    /// use plotters::prelude::*;
71    ///
72    /// let quartiles = Quartiles::new(&[7, 15, 36, 39, 40, 41]);
73    /// let values = quartiles.values();
74    /// assert_eq!(values, [-9.0, 20.25, 37.5, 39.75, 69.0]);
75    /// ```
76    pub fn values(&self) -> [f32; 5] {
77        [
78            self.lower_fence as f32,
79            self.lower as f32,
80            self.median as f32,
81            self.upper as f32,
82            self.upper_fence as f32,
83        ]
84    }
85
86    /// Get the quartiles median.
87    ///
88    /// - **returns** The median
89    ///
90    /// ```rust
91    /// use plotters::prelude::*;
92    ///
93    /// let quartiles = Quartiles::new(&[7, 15, 36, 39, 40, 41]);
94    /// assert_eq!(quartiles.median(), 37.5);
95    /// ```
96    pub fn median(&self) -> f64 {
97        self.median
98    }
99}
100
101#[cfg(test)]
102mod test {
103    use super::*;
104
105    #[test]
106    #[should_panic]
107    fn test_empty_input() {
108        let empty_array: [i32; 0] = [];
109        Quartiles::new(&empty_array);
110    }
111
112    #[test]
113    fn test_low_inputs() {
114        assert_eq!(
115            Quartiles::new(&[15.0]).values(),
116            [15.0, 15.0, 15.0, 15.0, 15.0]
117        );
118        assert_eq!(
119            Quartiles::new(&[10, 20]).values(),
120            [5.0, 12.5, 15.0, 17.5, 25.0]
121        );
122        assert_eq!(
123            Quartiles::new(&[10, 20, 30]).values(),
124            [0.0, 15.0, 20.0, 25.0, 40.0]
125        );
126    }
127}
plotters/data/quartiles.rs

plotters/data/
quartiles.rs
