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
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
/// Divide a collection into smaller chunks of a specified size,
/// preserving the order of elements.
///
/// This function takes a slice of items and splits it into multiple
/// chunks, each with a maximum of `size` elements. The order of elements
/// is preserved, and the last chunk may contain fewer elements if the
/// total number of elements is not perfectly divisible by `size`.
///
/// **Panics:**
/// Panics if `size` is less than or equal to 0.
///
/// **Time Complexity:**
/// O(n), where n is the number of elements in the collection.
///
/// # Arguments
///
/// * `collection` - A slice of items to be divided into chunks.
/// * `size` - The maximum number of elements each chunk should contain.
///
/// # Type Parameters
///
/// * `T` - The type of elements in the collection. Must implement `Clone`.
///
/// # Returns
///
/// * `Vec<Vec<T>>` - A vector of chunks, where each chunk is a vector of elements.
///
/// # Examples
///
/// ```rust
/// use lowdash::chunk;
///
/// let numbers = vec![1, 2, 3, 4, 5, 6, 7];
/// let chunks = chunk(&numbers, 3);
/// assert_eq!(
/// chunks,
/// vec![vec![1, 2, 3], vec![4, 5, 6], vec![7]]
/// );
/// ```
///
/// ```rust
/// use lowdash::chunk;
///
/// #[derive(Debug, PartialEq, Clone)]
/// struct Person {
/// name: String,
/// age: u32,
/// }
///
/// let people = vec![
/// Person { name: "Alice".to_string(), age: 25 },
/// Person { name: "Bob".to_string(), age: 30 },
/// Person { name: "Carol".to_string(), age: 35 },
/// Person { name: "Dave".to_string(), age: 40 },
/// ];
///
/// let chunks = chunk(&people, 2);
/// assert_eq!(
/// chunks,
/// vec![
/// vec![
/// Person { name: "Alice".to_string(), age: 25 },
/// Person { name: "Bob".to_string(), age: 30 },
/// ],
/// vec![
/// Person { name: "Carol".to_string(), age: 35 },
/// Person { name: "Dave".to_string(), age: 40 },
/// ],
/// ]
/// );
/// ```
pub fn chunk<T>(collection: &[T], size: usize) -> Vec<Vec<T>>
where
T: Clone,
{
if size == 0 {
panic!("Chunk size must be greater than 0");
}
let mut result: Vec<Vec<T>> = Vec::new();
let mut start = 0;
while start < collection.len() {
let end = if start + size > collection.len() {
collection.len()
} else {
start + size
};
let chunk = collection[start..end].to_vec();
result.push(chunk);
start += size;
}
result
}
#[cfg(test)]
mod tests {
use super::*;
#[derive(Debug, PartialEq, Clone)]
struct Person {
name: String,
age: u32,
}
#[derive(Debug, PartialEq, Clone)]
struct Item {
id: u32,
value: String,
}
#[test]
fn test_chunk_integers_exact_division() {
let numbers = vec![1, 2, 3, 4, 5, 6];
let chunks = chunk(&numbers, 2);
assert_eq!(chunks, vec![vec![1, 2], vec![3, 4], vec![5, 6]]);
}
#[test]
fn test_chunk_integers_non_exact_division() {
let numbers = vec![1, 2, 3, 4, 5, 6, 7];
let chunks = chunk(&numbers, 3);
assert_eq!(chunks, vec![vec![1, 2, 3], vec![4, 5, 6], vec![7]]);
}
#[test]
fn test_chunk_strings_exact_division() {
let strings = vec!["a", "b", "c", "d"];
let chunks = chunk(&strings, 2);
assert_eq!(chunks, vec![vec!["a", "b"], vec!["c", "d"]]);
}
#[test]
fn test_chunk_strings_non_exact_division() {
let strings = vec!["apple", "banana", "cherry"];
let chunks = chunk(&strings, 2);
assert_eq!(chunks, vec![vec!["apple", "banana"], vec!["cherry"]]);
}
#[test]
fn test_chunk_with_structs() {
let people = vec![
Person {
name: "Alice".to_string(),
age: 25,
},
Person {
name: "Bob".to_string(),
age: 30,
},
Person {
name: "Carol".to_string(),
age: 35,
},
Person {
name: "Dave".to_string(),
age: 40,
},
];
let chunks = chunk(&people, 3);
assert_eq!(
chunks,
vec![
vec![
Person {
name: "Alice".to_string(),
age: 25
},
Person {
name: "Bob".to_string(),
age: 30
},
Person {
name: "Carol".to_string(),
age: 35
},
],
vec![Person {
name: "Dave".to_string(),
age: 40
},],
]
);
}
#[test]
fn test_chunk_with_empty_collection() {
let empty: Vec<i32> = vec![];
let chunks = chunk(&empty, 3);
assert_eq!(chunks, Vec::<Vec<i32>>::new());
}
#[test]
fn test_chunk_with_size_larger_than_collection() {
let numbers = vec![1, 2];
let chunks = chunk(&numbers, 5);
assert_eq!(chunks, vec![vec![1, 2]]);
}
#[test]
#[should_panic(expected = "Chunk size must be greater than 0")]
fn test_chunk_with_zero_size() {
let numbers = vec![1, 2, 3];
let _chunks = chunk(&numbers, 0);
}
#[test]
fn test_chunk_with_size_one() {
let numbers = vec![1, 2, 3];
let chunks = chunk(&numbers, 1);
assert_eq!(chunks, vec![vec![1], vec![2], vec![3]]);
}
#[test]
fn test_chunk_with_mixed_types() {
let items = vec![
Item {
id: 1,
value: "one".to_string(),
},
Item {
id: 2,
value: "two".to_string(),
},
Item {
id: 3,
value: "three".to_string(),
},
Item {
id: 4,
value: "four".to_string(),
},
Item {
id: 5,
value: "five".to_string(),
},
];
let chunks = chunk(&items, 2);
assert_eq!(
chunks,
vec![
vec![
Item {
id: 1,
value: "one".to_string()
},
Item {
id: 2,
value: "two".to_string()
},
],
vec![
Item {
id: 3,
value: "three".to_string()
},
Item {
id: 4,
value: "four".to_string()
},
],
vec![Item {
id: 5,
value: "five".to_string()
},],
]
);
}
#[test]
fn test_chunk_preserves_order() {
let numbers = vec![5, 4, 3, 2, 1];
let chunks = chunk(&numbers, 2);
assert_eq!(chunks, vec![vec![5, 4], vec![3, 2], vec![1]]);
}
#[test]
fn test_chunk_with_optionals() {
let collection = vec![Some(1), None, Some(2), None, Some(3)];
let chunks = chunk(&collection, 2);
assert_eq!(
chunks,
vec![vec![Some(1), None], vec![Some(2), None], vec![Some(3)],]
);
}
#[test]
fn test_chunk_with_nan_floats() {
let float_collection = vec![std::f64::NAN, 2.2, std::f64::NAN, 4.4, 5.5];
let chunks = chunk(&float_collection, 2);
assert_eq!(chunks.len(), 3);
assert_eq!(chunks[0].len(), 2);
assert!(chunks[0][0].is_nan());
assert_eq!(chunks[0][1], 2.2);
assert_eq!(chunks[1].len(), 2);
assert!(chunks[1][0].is_nan());
assert_eq!(chunks[1][1], 4.4);
assert_eq!(chunks[2], vec![5.5]);
}
}