我查看过其他帖子，包括Group by variable integer range using Linq
但是我没有发现任何与我的问题类似的东西......我试图将整数序列分组为不连续的整数范围。例如，如果我有一组1-100的连续整数然后我的设置跳过101，我想创建一个记录，记录＃1和＃100记录的日期，其中记录＃1的日期是开始日期，＃100是结束日期。
每个连续整数范围都会创建一个新记录，以添加到记录列表中，以指示范围开始和结束时的日期。如果范围只包含一个整数值（例如，整数范围从1-100,102和104-200），则单个整数范围将具有相同的开始和结束日期。
有什么建议吗？
答案 0 :(得分：7)
您可以制作一个扩展方法来执行此操作：
static class EnumerableIntExtensions {
public static IEnumerable<IEnumerable<T>> ToContiguousSequences<T>(
this IEnumerable<T> sequence,
Func<T, T> next
) {
Contract.Requires(sequence != null);
Contract.Requires(next != null);
var e = sequence.GetEnumerator();
if (!e.MoveNext()) {
throw new InvalidOperationException("Sequence is empty.");
}
var currentList = new List<T> { e.Current };
while (e.MoveNext()) {
T current = e.Current;
if (current.Equals(next(currentList.Last()))) {
currentList.Add(current);
}
else {
yield return currentList;
currentList = new List<T> { current };
}
}
yield return currentList;
}
}
用法：
var sequence = Enumerable.Range(1, 100)
.Concat(new[] { 102 })
.Concat(Enumerable.Range(104, 97));
var sequences = sequence.ToContiguousSequences(n => n + 1);
foreach(var contiguousSequence in sequences) {
Console.WriteLine(String.Join(", ", contiguousSequence.Select(n => n.ToString())));
}
输出：
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
102
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
答案 1 :(得分：0)
我不知道您是否能够使用提供的LINQ函数执行此操作，但以下函数：
public static IEnumerable<IEnumerable<T>> GroupWhile<T>(this IEnumerable<T> values, Func<Int32, Boolean> predicate)
{
var i = 0;
var currentSet = new List<T>();
while (i < values.Count())
{
if (predicate(i))
currentSet.Add(values.Skip(i).First());
else
{
yield return currentSet;
currentSet = new List<T>(new[] {values.Skip(i).First()});
}
i++;
}
yield return currentSet;
}
使用如下：
var ints = new[] {1, 2, 4, 5, 7, 8};
var groups = ints.GroupWhile(i => i == 0 || ints[i - 1] == ints[i] - 1).ToList();
可能适合该法案。
答案 2 :(得分：0)
这是我创建的可能有用的示例类。它将整数序列转换为一组范围。该代码适用于LINQPad。
void Main()
{
ContiguousNumberLine line = new ContiguousNumberLine();
List<Int64> testItems = new List<Int64>() { 1, 2, 4, 5, 7, 9, 11, 10, 3, 6, 8, 8 };
foreach(Int64 item in testItems)
{
line.Add(item);
line.numberLine.Dump(string.Format("After adding {0}", item));
}
line.Add(new List<Int64>() { 12, 14, 15, 16 });
line.numberLine.Dump("After adding 12, 14, 15, 16");
line.Add(new List<Int64>() { 17, 18, 19, 20 });
line.numberLine.Dump("After adding 17, 18, 19, 20");
foreach(var item in line.numberLine)
{
Console.WriteLine(string.Format("{0}\t{1}", item.Key, item.Value));
}
}
// Define other methods and classes here
public class ContiguousNumberLine
{
public SortedList<Int64, Int64> numberLine { get; private set; }
public ContiguousNumberLine()
{
numberLine = new SortedList<Int64, Int64>();
}
public bool IsPresent(Int64 input)
{
if (numberLine.ContainsKey(input))
{
return true;
}
else
{
foreach(var numRange in numberLine)
{
if (numRange.Key > input)
{
return false;
}
if (numRange.Value < input)
{
continue;
}
if (numRange.Key <= input && input <= numRange.Value)
{
return true;
}
}
return false;
}
}
public bool IsPresent(List<Int64> input)
{
if (IsContiguous(input))
{
return IsPresentRange(input.First(), input.Last());
}
else
{
foreach(Int64 item in input)
{
if (this.IsPresent(item))
{
return true;
}
}
}
return false;
}
public bool IsPresentRange(Int64 first, Int64 last)
{
// naive implementation
for(Int64 i = first; i <= last; i++)
{
if (this.IsPresent(i))
{
return true;
}
}
return false;
}
public bool IsContiguous(List<Int64> input)
{
Int64? first = null;
Int64? last = null;
foreach(Int64 item in input)
{
if (first == null)
{
first = item;
last = item;
continue;
}
if (last.Value +1 == item)
{
last = item;
continue;
}
else
{
return false;
}
}
return true;
}
public bool Add(Int64 input)
{
if (IsPresent(input))
{
return false;
}
else
{
//numberLine.Add(input, input);
// extend the last number of an existing range, then check if it bridges the gap to the next range
KeyValuePair<Int64, Int64>? itemToRemove1 = null;
KeyValuePair<Int64, Int64>? itemToRemove2 = null;
KeyValuePair<Int64, Int64> itemToAdd = new KeyValuePair<Int64, Int64>(input, input) ;
foreach(var numRange in numberLine)
{
if (numRange.Value + 1 == input)
{
itemToRemove1 = numRange;
itemToAdd = new KeyValuePair<Int64, Int64>(numRange.Key, numRange.Value + 1);
continue;
} else if (itemToRemove1 != null && numRange.Key -1 == input)
{
itemToRemove2 = new KeyValuePair<Int64, Int64>(numRange.Key, numRange.Value);
KeyValuePair<Int64, Int64> newRange = new KeyValuePair<Int64, Int64>(itemToAdd.Key, numRange.Value);
itemToAdd = newRange;
break;
} else if (numRange.Key - 1 == input)
{
itemToRemove1 = numRange;
itemToAdd = new KeyValuePair<Int64, Int64>(input, numRange.Value);
break;
} else if (numRange.Key > input)
{
itemToAdd = new KeyValuePair<Int64, Int64>(input, input);
break;
}
}
if (itemToRemove1 != null)
{
numberLine.Remove(itemToRemove1.Value.Key);
}
if (itemToRemove2 != null)
{
numberLine.Remove(itemToRemove2.Value.Key);
}
numberLine.Add(itemToAdd.Key, itemToAdd.Value);
return true;
}
}
public bool Add(List<Int64> input)
{
// check if we can use the optimized version
if (IsContiguous(input))
{
return this.AddRange(input.First(), input.Last());
}
else
{
if(IsPresent(input))
{
return false;
}
foreach(Int64 item in input)
{
this.Add(item);
}
return true;
}
}
public bool AddRange(Int64 first, Int64 last)
{
//throw new NotImplementedException();
if(IsPresentRange(first, last))
{
return false;
}
// naive implementation below (TODO: write optimized version)
for(Int64 i = first; i <= last; i++)
{
this.Add(i);
}
return true;
}
}