1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
use crate::percentile;
/// Calculate the median value of a collection.
/// The median is the 50th percentile of a collection.
/// For collections with an even number of elements, the median is the average of the two middle values.
/// The collection will be sorted before calculation.
///
/// # Arguments
/// * `collection` - A slice of items to calculate the median from
///
/// # Returns
/// * `Option<f64>` - The median value, or None if the collection is empty
///
/// # Examples
/// ```rust
/// use lowdash::median;
/// let numbers = vec![1, 3, 5, 2, 4];
/// let result = median(&numbers);
/// assert!((result.unwrap() - 3.0).abs() < f64::EPSILON);
/// ```
///
/// ```rust
/// use lowdash::median;
/// let numbers = vec![1, 2, 3, 4];
/// let result = median(&numbers);
/// assert!((result.unwrap() - 2.5).abs() < f64::EPSILON);
/// ```
pub fn median<T>(collection: &[T]) -> Option<f64>
where
T: Copy + Into<f64> + PartialOrd,
{
percentile(collection, 50.0)
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test_median_odd() {
let numbers = vec![1, 3, 5, 2, 4];
let result = median(&numbers);
assert!((result.unwrap() - 3.0).abs() < f64::EPSILON);
}
#[test]
fn test_median_even() {
let numbers = vec![1, 2, 3, 4];
let result = median(&numbers);
assert!((result.unwrap() - 2.5).abs() < f64::EPSILON);
}
#[test]
fn test_median_empty() {
let empty: Vec<i32> = vec![];
assert_eq!(median(&empty), None);
}
#[test]
fn test_median_single() {
let numbers = vec![42];
let result = median(&numbers);
assert!((result.unwrap() - 42.0).abs() < f64::EPSILON);
}
#[test]
fn test_median_unsorted() {
let numbers = vec![5, 2, 1, 4, 3];
let result = median(&numbers);
assert!((result.unwrap() - 3.0).abs() < f64::EPSILON);
}
#[test]
fn test_median_with_duplicates() {
let numbers = vec![1, 2, 2, 3, 3];
let result = median(&numbers);
assert!((result.unwrap() - 2.0).abs() < f64::EPSILON);
}
#[test]
fn test_median_float() {
let numbers = vec![1.5, 2.5, 3.5];
let result = median(&numbers);
assert!((result.unwrap() - 2.5).abs() < f64::EPSILON);
}
#[test]
fn test_median_negative() {
let numbers = vec![-5, -2, -1, -4, -3];
let result = median(&numbers);
assert!((result.unwrap() - (-3.0)).abs() < f64::EPSILON);
}
}