均衡数据字典

Question

Dictionary<DateTime, int> data1
Dictionary<DateTime, int> data2

未排序

 if the dates in data1 is from **1/1/2000 - 1/1/2009** and the dates in data2 is from **1/1/2001 - 1/1/2007** then both Dictionaries<> should have the date ranging from **1/1/2001 - 1/1/2007** 

相反。

bascailly我需要删除较小范围之外的条目，如何使用C＃和linq做到这一点？

Answer 1

DateTime min1 = data1.Keys.Min();
DateTime min2 = data2.Keys.Min();
DateTime max1 = data1.Keys.Max();
DateTime max2 = data1.Keys.Max();
if(min1 < min2 && max1 > max2) {
    data1 = ShrinkDictionary(data1, min2, max2);
}
else if(min2 < min1 && max2 > max1) {
    data2 = ShrinkDictionary(data2, min1, max1);
}
else {
    // this should never happen
    throw new Exception();
}

这里ShrinkDictionary是：

public Dictionary<DateTime, int> ShrinkDictionary(
    Dictionary<DateTime, int> dict, DateTime min, DateTime max) {
    return dict.Where(kvp => InRange(kvp.Key, min, max))
               .ToDictionary(kvp => kvp.Key, kvp => kvp.Value);
}

InRange是易于推广的方法：

public bool InRange(DateTime date, DateTime min, DateTime max) {
    return (date >= min) && (date <= max);
}

Answer 2

我假设您只需要从data2中删除条目（而不是合并2个字典）

var min = data1.Keys.Min();
var max = data1.Keys.Max();
data2 = data2
    .Where(pair => pair.Key >= min && pair.Key < max)
    .ToDictionary(pair => pair.Key, pair => pair.Value);