statrs/statistics/
traits.rs

1use ::num_traits::float::Float;
2
3/// The `Min` trait specifies than an object has a minimum value
4pub trait Min<T> {
5    /// Returns the minimum value in the domain of a given distribution
6    /// if it exists, otherwise `None`.
7    ///
8    /// # Examples
9    ///
10    /// ```
11    /// use statrs::statistics::Min;
12    /// use statrs::distribution::Uniform;
13    ///
14    /// let n = Uniform::new(0.0, 1.0).unwrap();
15    /// assert_eq!(0.0, n.min());
16    /// ```
17    fn min(&self) -> T;
18}
19
20/// The `Max` trait specifies that an object has a maximum value
21pub trait Max<T> {
22    /// Returns the maximum value in the domain of a given distribution
23    /// if it exists, otherwise `None`.
24    ///
25    /// # Examples
26    ///
27    /// ```
28    /// use statrs::statistics::Max;
29    /// use statrs::distribution::Uniform;
30    ///
31    /// let n = Uniform::new(0.0, 1.0).unwrap();
32    /// assert_eq!(1.0, n.max());
33    /// ```
34    fn max(&self) -> T;
35}
36pub trait DiscreteDistribution<T: Float> {
37    /// Returns the mean, if it exists.
38    fn mean(&self) -> Option<T> {
39        None
40    }
41    /// Returns the variance, if it exists.
42    fn variance(&self) -> Option<T> {
43        None
44    }
45    /// Returns the standard deviation, if it exists.
46    fn std_dev(&self) -> Option<T> {
47        self.variance().map(|var| var.sqrt())
48    }
49    /// Returns the entropy, if it exists.
50    fn entropy(&self) -> Option<T> {
51        None
52    }
53    /// Returns the skewness, if it exists.
54    fn skewness(&self) -> Option<T> {
55        None
56    }
57}
58
59pub trait Distribution<T: Float> {
60    /// Returns the mean, if it exists.
61    ///
62    /// # Examples
63    ///
64    /// ```
65    /// use statrs::statistics::Distribution;
66    /// use statrs::distribution::Uniform;
67    ///
68    /// let n = Uniform::new(0.0, 1.0).unwrap();
69    /// assert_eq!(0.5, n.mean().unwrap());
70    /// ```
71    fn mean(&self) -> Option<T> {
72        None
73    }
74    /// Returns the variance, if it exists.
75    ///
76    /// # Examples
77    ///
78    /// ```
79    /// use statrs::statistics::Distribution;
80    /// use statrs::distribution::Uniform;
81    ///
82    /// let n = Uniform::new(0.0, 1.0).unwrap();
83    /// assert_eq!(1.0 / 12.0, n.variance().unwrap());
84    /// ```
85    fn variance(&self) -> Option<T> {
86        None
87    }
88    /// Returns the standard deviation, if it exists.
89    ///
90    /// # Examples
91    ///
92    /// ```
93    /// use statrs::statistics::Distribution;
94    /// use statrs::distribution::Uniform;
95    ///
96    /// let n = Uniform::new(0.0, 1.0).unwrap();
97    /// assert_eq!((1f64 / 12f64).sqrt(), n.std_dev().unwrap());
98    /// ```
99    fn std_dev(&self) -> Option<T> {
100        self.variance().map(|var| var.sqrt())
101    }
102    /// Returns the entropy, if it exists.
103    ///
104    /// # Examples
105    ///
106    /// ```
107    /// use statrs::statistics::Distribution;
108    /// use statrs::distribution::Uniform;
109    ///
110    /// let n = Uniform::new(0.0, 1.0).unwrap();
111    /// assert_eq!(0.0, n.entropy().unwrap());
112    /// ```
113    fn entropy(&self) -> Option<T> {
114        None
115    }
116    /// Returns the skewness, if it exists.
117    ///
118    /// # Examples
119    ///
120    /// ```
121    /// use statrs::statistics::Distribution;
122    /// use statrs::distribution::Uniform;
123    ///
124    /// let n = Uniform::new(0.0, 1.0).unwrap();
125    /// assert_eq!(0.0, n.skewness().unwrap());
126    /// ```
127    fn skewness(&self) -> Option<T> {
128        None
129    }
130}
131
132/// The `Mean` trait implements the calculation of a mean.
133// TODO: Clarify the traits of multidimensional distributions
134pub trait MeanN<T> {
135    fn mean(&self) -> Option<T>;
136}
137
138// TODO: Clarify the traits of multidimensional distributions
139pub trait VarianceN<T> {
140    fn variance(&self) -> Option<T>;
141}
142
143/// The `Median` trait returns the median of the distribution.
144pub trait Median<T> {
145    /// Returns the median.
146    ///
147    /// # Examples
148    ///
149    /// ```
150    /// use statrs::statistics::Median;
151    /// use statrs::distribution::Uniform;
152    ///
153    /// let n = Uniform::new(0.0, 1.0).unwrap();
154    /// assert_eq!(0.5, n.median());
155    /// ```
156    fn median(&self) -> T;
157}
158
159/// The `Mode` trait specifies that an object has a closed form solution
160/// for its mode(s)
161pub trait Mode<T> {
162    /// Returns the mode, if one exists.
163    ///
164    /// # Examples
165    ///
166    /// ```
167    /// use statrs::statistics::Mode;
168    /// use statrs::distribution::Uniform;
169    ///
170    /// let n = Uniform::new(0.0, 1.0).unwrap();
171    /// assert_eq!(Some(0.5), n.mode());
172    /// ```
173    fn mode(&self) -> T;
174}
statrs/statistics/traits.rs

statrs/statistics/
traits.rs
