C# LINQ选择多个列作为单独的数组
我有表4列C# LINQ选择多个列作为单独的数组,c#,visual-studio-2010,performance,linq,linq-to-sql,C#,Visual Studio 2010,Performance,Linq,Linq To Sql,我有表4列 JobId StateId Salary Expense 1 1 35,000 31,000 1 1 33,000 25,000 1 2 28,000 26,000 2 2 7,000 16,000 2 2 6,000 20,000 2
JobId StateId Salary Expense
1 1 35,000 31,000
1 1 33,000 25,000
1 2 28,000 26,000
2 2 7,000 16,000
2 2 6,000 20,000
2 1 9,000 22,000
2 1 15,000 29,000
通过在C中使用LINQ,我希望按JobId和StateId组合进行分组。对于每个组合,我需要一个薪水数组和费用数组
我可以得到一列作为一个数组,通过使用
(from r in myTable.AsEnumerable()
group r by new {
jobId = r.Field<int>("JobId"),
stateId = r.Field<int>("StateId")
}).ToDictionary(
l => Tuple.Create(l.Key.jobId, l.Key.stateId),
l=> (from i in l select i.Field<double>("Salary")).AsEnumerable()
);
我怎样才能在两个数组中为每个组设置薪资和费用
我的目标是找到每个组合的平均工资和平均费用,并进行其他操作。或者至少告诉我如何选择多个列作为单独的数组
注意:我不希望为每个组合收集匿名对象。不要将LINQ用于此类语句。如果您需要计算分组和计算某种平均工资/费用,您可以尝试列出:
List<myType> myList = new List<myType>();
//add stuff to myList
List<myType> JobID1 = new List<myType();
List<myType> JobID2 = new List<myType();
foreach(var item in myList)
{
if(item.JobID == 1)
JobID1.add(item);
if(item.JobID == 2)
JobID2.add(item);
}
int avgSalOne;
foreach(var item in JobID1)
{
avgSalOne += item.Salary;
}
avgSalOne = avgSaleOne / JobID2.Count;
//Note that you get Job Id 2 average salary the same way, and also the Expense by changing item. Salary to item.Expense
不要将LINQ用于此类语句。如果您需要计算分组和计算某种平均工资/费用,您可以尝试列出:
List<myType> myList = new List<myType>();
//add stuff to myList
List<myType> JobID1 = new List<myType();
List<myType> JobID2 = new List<myType();
foreach(var item in myList)
{
if(item.JobID == 1)
JobID1.add(item);
if(item.JobID == 2)
JobID2.add(item);
}
int avgSalOne;
foreach(var item in JobID1)
{
avgSalOne += item.Salary;
}
avgSalOne = avgSaleOne / JobID2.Count;
//Note that you get Job Id 2 average salary the same way, and also the Expense by changing item. Salary to item.Expense
要在查询中选择两个不同的列作为集合,可以执行以下操作:
var result =
(from r in myTable.AsEnumerable()
group r by new
{
jobId = r.Field<int>("JobId"),
stateId = r.Field<int>("StateId")
} into g
select new
{
g.Key,
Salaries = g.Select(x => x.Field<double>("Salary")),
Expenses = g.Select(x => x.Field<double>("Expense"))
})
.ToDictionary(
l => Tuple.Create(l.Key.jobId, l.Key.stateId),
l => new { l.Salaries, l.Expenses }
);
但如果你真正需要的只是平均数,那么这就行了:
var result =
(from r in myTable.AsEnumerable()
group r by new
{
jobId = r.Field<int>("JobId"),
stateId = r.Field<int>("StateId")
} into g
select new
{
g.Key,
AverageSalary = g.Average(x => x.Field<double>("Salary")),
AverageExpense = g.Average(x => x.Field<double>("Expense"))
})
.ToDictionary(
l => Tuple.Create(l.Key.jobId, l.Key.stateId),
l => new { l.AverageSalary, l.AverageExpense }
);
要在查询中选择两个不同的列作为集合,可以执行以下操作:
var result =
(from r in myTable.AsEnumerable()
group r by new
{
jobId = r.Field<int>("JobId"),
stateId = r.Field<int>("StateId")
} into g
select new
{
g.Key,
Salaries = g.Select(x => x.Field<double>("Salary")),
Expenses = g.Select(x => x.Field<double>("Expense"))
})
.ToDictionary(
l => Tuple.Create(l.Key.jobId, l.Key.stateId),
l => new { l.Salaries, l.Expenses }
);
但如果你真正需要的只是平均数,那么这就行了:
var result =
(from r in myTable.AsEnumerable()
group r by new
{
jobId = r.Field<int>("JobId"),
stateId = r.Field<int>("StateId")
} into g
select new
{
g.Key,
AverageSalary = g.Average(x => x.Field<double>("Salary")),
AverageExpense = g.Average(x => x.Field<double>("Expense"))
})
.ToDictionary(
l => Tuple.Create(l.Key.jobId, l.Key.stateId),
l => new { l.AverageSalary, l.AverageExpense }
);
如果他开始将JobID与StateID进行组合,将会有很多IF语句。我有一个非常大的数组,我想利用LINQ的延迟执行以及并行execution@KhanSharp这里不会有并行执行,如果他开始组合执行我有一个非常大的数组,我想利用LINQ的延迟执行和并行execution@KhanSharp你不会在这里并行执行谢谢你的回答。除了平均水平外,我还需要做一些额外的工作。在后面的过程中,我想为一个特定的组合选择费用/薪水数组,并做一些调整processing@KhanSharp在这种情况下,您可以使用我的第一个代码示例。为了完整起见,我提供了更多的信息。谢谢你的回答。除了平均水平外,我还需要做一些额外的工作。在后面的过程中,我想为一个特定的组合选择费用/薪水数组,并做一些调整processing@KhanSharp在这种情况下,您可以使用我的第一个代码示例。为了完整起见,我已经包含了更多的信息。