ndhistogram/axis/
uniform.rs

1use std::fmt::{Debug, Display};
2
3use num_traits::{Float, Num, NumCast, NumOps};
4
5use crate::error::AxisError;
6
7use super::{Axis, BinInterval};
8
9/// An axis with equal sized bins.
10///
11/// An axis with N equally spaced, equal sized, bins between [low, high).
12/// Below (above) this range is an underflow (overflow) bin.
13/// Hence this axis has N+2 bins.
14///
15/// For floating point types, positive and negative infinities map to overflow
16/// and underflow bins respectively. NaN maps to the overflow bin.
17///
18/// # Example
19/// Create a 1D histogram with 10 uniform bins between -5.0 and 5.0, plus overflow and underflow bins.
20/// ```rust
21///    use ndhistogram::{ndhistogram, Histogram};
22///    use ndhistogram::axis::{Axis, Uniform, BinInterval};
23///    # fn main() -> Result<(), ndhistogram::Error> {
24///    let hist = ndhistogram!(Uniform::new(10, -5.0, 5.0)?);
25///    let axis = &hist.axes().as_tuple().0;
26///    assert_eq!(axis.bin(0), Some(BinInterval::underflow(-5.0)));
27///    assert_eq!(axis.bin(1), Some(BinInterval::new(-5.0, -4.0)));
28///    assert_eq!(axis.bin(11), Some(BinInterval::overflow(5.0)));
29///    # Ok(()) }
30/// ```
31#[derive(Default, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug)]
32#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
33pub struct Uniform<T = f64> {
34    num: usize,
35    low: T,
36    high: T,
37    step: T,
38}
39
40impl<T> Uniform<T>
41where
42    T: PartialOrd + Num + NumCast + NumOps + Copy,
43{
44    /// Factory method to create an axis with num uniformly spaced bins in the range [low, high). Under/overflow bins cover values outside this range.
45    ///
46    /// Only implemented for [Float]. Use [Uniform::with_step_size] for integers.
47    ///
48    pub fn new(num: usize, low: T, high: T) -> Result<Self, AxisError>
49    where
50        T: Float,
51    {
52        if num == 0 {
53            return Err(AxisError::InvalidNumberOfBins);
54        }
55        if low == high {
56            return Err(AxisError::InvalidAxisRange);
57        }
58        let (low, high) = if low > high { (high, low) } else { (low, high) };
59        let step = (high - low) / T::from(num).ok_or(AxisError::InvalidNumberOfBins)?;
60        Ok(Self {
61            num,
62            low,
63            high,
64            step,
65        })
66    }
67
68    /// Factory method to create an axis with num uniformly spaced bins in the range [low, low+num*step). Under/overflow bins cover values outside this range.
69    ///
70    /// The number of bins and step size must both be greater than zero, otherwise an error is returned.
71    /// The number of bins must be representable in the type T, otherwise an error is returned.
72    pub fn with_step_size(num: usize, low: T, step: T) -> Result<Self, AxisError> {
73        let high = T::from(num).ok_or(AxisError::InvalidNumberOfBins)? * step + low;
74        if num == 0 {
75            return Err(AxisError::InvalidNumberOfBins);
76        }
77        if step <= T::zero() {
78            return Err(AxisError::InvalidStepSize);
79        }
80        let (low, high) = if low > high { (high, low) } else { (low, high) };
81        Ok(Self {
82            num,
83            low,
84            high,
85            step,
86        })
87    }
88}
89
90impl<T> Uniform<T> {
91    /// Low edge of axis (excluding underflow bin).
92    pub fn low(&self) -> &T {
93        &self.low
94    }
95
96    /// High edge of axis (excluding overflow bin).
97    pub fn high(&self) -> &T {
98        &self.high
99    }
100}
101
102// TODO: relax float restriction or add implementation for Integers
103impl<T: PartialOrd + NumCast + NumOps + Copy> Axis for Uniform<T> {
104    type Coordinate = T;
105    type BinInterval = BinInterval<T>;
106
107    #[inline]
108    fn index(&self, coordinate: &Self::Coordinate) -> Option<usize> {
109        if coordinate < &self.low {
110            return Some(0);
111        }
112        if coordinate >= &self.high {
113            return Some(self.num + 1);
114        }
115        let steps = (*coordinate - self.low) / (self.step);
116        Some(steps.to_usize().unwrap_or(self.num) + 1)
117    }
118
119    fn num_bins(&self) -> usize {
120        self.num + 2
121    }
122
123    fn bin(&self, index: usize) -> std::option::Option<<Self as Axis>::BinInterval> {
124        if index == 0 {
125            return Some(Self::BinInterval::underflow(self.low));
126        } else if index == (self.num + 1) {
127            return Some(Self::BinInterval::overflow(self.high));
128        } else if index > (self.num + 1) {
129            return None;
130        }
131        let start =
132            self.low + (T::from(index - 1)?) * (self.high - self.low) / (T::from(self.num)?);
133        let end = self.low + (T::from(index)?) * (self.high - self.low) / (T::from(self.num)?);
134        Some(Self::BinInterval::new(start, end))
135    }
136
137    fn indices(&self) -> Box<dyn Iterator<Item = usize>> {
138        Box::new(0..self.num_bins())
139    }
140}
141
142impl<T: Display> Display for Uniform<T> {
143    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
144        write!(
145            f,
146            "Axis{{# bins={}, range=[{}, {}), class={}}}",
147            self.num,
148            self.low,
149            self.high,
150            stringify!(Uniform)
151        )
152    }
153}
154
155impl<'a, T> IntoIterator for &'a Uniform<T>
156where
157    Uniform<T>: Axis,
158{
159    type Item = (usize, <Uniform<T> as Axis>::BinInterval);
160    type IntoIter = Box<dyn Iterator<Item = Self::Item> + 'a>;
161
162    fn into_iter(self) -> Self::IntoIter {
163        self.iter()
164    }
165}
ndhistogram/axis/uniform.rs

ndhistogram/axis/
uniform.rs
