[英]Linq Grouping by Date (month)
I would like to know how I could group some data by month and sum a field. 我想知道如何按月对一些数据进行分组并总结一个字段。 For example I have a list of MyObjects(DateTimeField, AmountField)
. 例如,我有一个MyObjects(DateTimeField, AmountField)
列表MyObjects(DateTimeField, AmountField)
。 I want to group by DateTimeField
, but not entire date, just by month, and then sum the AmountField
for each month. 我想按DateTimeField
分组,但不是整个日期,只是按月AmountField
,然后将每月的AmountField
相加。
I don't know why the objectgrouped
is null? 我不知道为什么objectgrouped
是null?
IEnumerable<MyObject> objectList= GetMyObject();
var ObjectGrouped = objectList.GroupBy(l => l.ObjectDate.GetValueOrDefault().Month)
.Select(lg =>
new
{
CurrentMonth = lg.Key,
Total = lg.Sum(w => w.ObjectAmount)
});
ObjectDate ObjectAmount
1/1/2013 3.3
3/1/2013 6.9
13/2/2013 5
3/4/2013 3.6
13/4/2013 15.2
I assume by "month" you mean "month and year":
我假设“月”表示“月份和年份”:
To ignore null values: 要忽略空值:
var query = myList.Where(i => i.DateTimeField.HasValue)
.GroupBy(i => i.DateTimeField.Value.Month)
.Select(g => new {
Month=g.Key,
Total=g.Sum(i=>i.AmountField)
});
to put null values in a separate bucket ("0" month): 将空值放在一个单独的存储桶中(“0”月):
var query = myList.GroupBy(i => i.DateTimeField.HasValue ? i.DateTimeField.Value.Month : 0)
.Select(g => new {
Month=g.Key,
Total=g.Sum(i=>i.AmountField)
});
Try this: 试试这个:
List<DateTime> list = new List<DateTime>();
var grouppedResult = list.GroupBy(x => x.Month);
var groups = list.GroupBy(l => l.DateTimeField.Year * 12 + l.DateTimeField.Month)
.Select(g => new {
Month=g.First().DateTimeField,
Sum=g.Select(a=>a.AmountField).Sum()
})
.ToList();
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.