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
use std::ops::{Add, Div};
/// Calculates the arithmetic mean of a collection of numbers.
/// If the collection is empty, returns zero.
///
/// # Arguments
/// * `collection` - A slice of numbers.
///
/// # Returns
/// * `T` - The arithmetic mean of the collection.
///
/// # Examples
/// ```rust
/// use lowdash::mean;
/// let numbers = vec![1.0, 2.0, 3.0, 4.0, 5.0];
/// let result = mean(&numbers);
/// assert_eq!(result, 3.0);
/// ```
///
/// ```rust
/// use lowdash::mean;
/// let numbers = vec![1, 2, 3, 4, 5];
/// let result = mean(&numbers);
/// assert_eq!(result, 3);
/// ```
///
/// ```rust
/// use lowdash::mean;
/// let empty: Vec<f64> = vec![];
/// let result = mean(&empty);
/// assert_eq!(result, 0.0);
/// ```
pub fn mean<T>(collection: &[T]) -> T
where
T: Add<Output = T> + Div<Output = T> + From<u8> + Copy,
{
let length = collection.len();
if length == 0 {
return T::from(0);
}
let sum = collection.iter().fold(T::from(0), |acc, &x| acc + x);
sum / T::from(length as u8)
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test_mean_integers() {
let numbers = vec![1, 2, 3, 4, 5];
assert_eq!(mean(&numbers), 3);
}
#[test]
fn test_mean_floats() {
let numbers = vec![1.0, 2.0, 3.0, 4.0, 5.0];
assert_eq!(mean(&numbers), 3.0);
}
#[test]
fn test_mean_empty() {
let empty: Vec<f64> = vec![];
assert_eq!(mean(&empty), 0.0);
}
#[test]
fn test_mean_single_element() {
let numbers = vec![42];
assert_eq!(mean(&numbers), 42);
}
#[test]
fn test_mean_negative_numbers() {
let numbers = vec![-1.0, -2.0, -3.0, -4.0, -5.0];
assert_eq!(mean(&numbers), -3.0);
}
#[test]
fn test_mean_mixed_positive_negative() {
let numbers = vec![-2, -1, 0, 1, 2];
assert_eq!(mean(&numbers), 0);
}
#[test]
fn test_mean_decimal_result() {
let numbers = vec![1.0, 2.0, 3.0];
assert_eq!(mean(&numbers), 2.0);
}
}