Break a list into fixed-size pieces
A bulk API takes at most a hundred records per call, so a long list has to be handed over in pieces.
- Every piece is the given size except possibly the last, which takes what is left.
- A size of zero or less gives an empty result.
- An empty input gives an empty result, not a list holding one empty piece.
ChunkList(values: list<int>, perChunk: int) → list<list<int>>
C# needs a compiler and Drill does not host one yet, so this page is the reference rather than an exercise: the problem, worked examples, and the solution in full. To type it out, the same problem runs in Python.
Where you start
public List<List<int>> ChunkList(List<int> values, int perChunk) {
}Worked examples
| Call | Result |
|---|---|
ChunkList(new List<int> { 1, 2, 3, 4, 5 }, 2) | new List<List<int>> { new List<int> { 1, 2 }, new List<int> { 3, 4 }, new List<int> { 5 } } |
ChunkList(new List<int> { 1, 2, 3, 4 }, 2) | new List<List<int>> { new List<int> { 1, 2 }, new List<int> { 3, 4 } } |
ChunkList(new List<int> { 1 }, 5) | new List<List<int>> { new List<int> { 1 } } |
ChunkList(new List<int> { }, 2) | new List<List<int>> { } |
Hint
Step the index forward by the chunk size and slice, rather than pushing one item at a time.
Reference solution in C#
public List<List<int>> ChunkList(List<int> values, int perChunk) {
var result = new List<List<int>>();
if (perChunk <= 0) return result;
for (int i = 0; i < values.Count; i += perChunk) {
result.Add(values.GetRange(i, Math.Min(perChunk, values.Count - i)));
}
return result;
}