我有一個類似的物件陣列：
class StateVisitor
{
string FirstName { get; set; }
string LastName { get; set; }
string StateViseted { get; set; }
}
StateVisitor[] StateVisitors = {
new() { FirstName = "Bob", LastName = "Smith", StateViseted = "AL" },
new() { FirstName = "Bob", LastName = "Smith", StateViseted = "AK" },
new() { FirstName = "Bob", LastName = "Jones", StateViseted = "AL" },
new() { FirstName = "Sam", LastName = "Smith", StateViseted = "UT" }
}
我想做這樣的事情：
class VisitorsWithCombinedStates {
string FirstName { get; set; }
string LastName { get; set; }
string[] StatesVisetedArray { get; set; }
}
VisitorsWithCombinedStates[] visitorsWithCombinedStates = StateVisitors... /* Linq magic? */
visitorsWithCombinedStates.ForEach(v
=> Console.WriteLine($"{v.FirstName} {v.LastName} visited {string.Join(", ",v.StatesVisitedArray)}"));
// "Bob Smith visited AL, AK"
// "Bob Jones visited AL"
// "Sam Smith visited UT"
有沒有一種簡單的方法，在 C# 中（可能使用 LINQ）將第一個陣列展平為第二個陣列，在其中創建一個訪問狀態的陣列？
uj5u.com熱心網友回復：
您想按名字和姓氏的組合對專案進行分組，并將分組結果投影為訪問過的狀態
var groups = stateVisitors.GroupBy(sv => new
{
sv.FirstName,
sv.LastName,
},
sv => sv.StateVisited );
輸出：
foreach(var g in groups)
{
// g.Key.FirstName
// g.Key.LastName
// g is IEnumerable<string> of visited states
}
uj5u.com熱心網友回復：
一個示例，填充您的VisitorWithCombinedStates類：
VisitorsWithCombinedStates[] visitorsWithCombinedStates = StateVisitors.GroupBy(x => new { x.FirstName, x.LastName},x => x.StateViseted)
.Select(x => new VisitorsWithCombinedStates { FirstName = x.Key.FirstName, LastName = x.Key.LastName, StatesVisetedArray = x.ToArray() }).ToArray();
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