WebJan 21, 2024 · Assuming I have this data loaded into a collection of IEnumerable called books, I can then use GroupBy to group items by various properties by specifying the key selector.. For example, I’ll group by author by using books.GroupBy(b => b.Author). This results in an IEnumerable>.Don’t let that return type scare you … WebThe values of an IGrouping are accessed much as the elements of an IEnumerable are accessed. For example, you can access the values by using a foreach in Visual C# or For Each in Visual Basic loop to iterate through the IGrouping object. The Example section contains a code example that …

c# - How to get value from IGrouping where key and value in …

Web分组时使用XML PATH操作行数据 [英]Using XML PATH to manipulate row data when grouping WebSep 1, 2015 · 方法是使用reset_index。. 利用 group by对dataframe 分组 并写入csv文件. group by: 实现dataframe某一列相等的行的其他列的聚合（ 分组 ） group by 分组 后，通过apply (list)可以把column_index（1个值）对应的column_1（1个或多个值）变为list格式，输出为len (column_index)个 ( 一个index+1 ... earth magnets ebay

C# 获得；“价值”；iGroup中的属性_C#_Linq_Data …

WebApr 1, 2024 · Solution 3. If you want to stick with the List> approach, grouping by the first value and summing the second, something like this should work: C#. return userTxns.GroupBy (u => u [0], (key, values) => new List { key, values.Select (l => l [1]).Sum () }).ToList (); Personally, I'd be inclined to use a dictionary instead: Web得票数 -1. 只需执行以下操作：. // this will "split" the list into groups var groups = list.GroupBy(x => x.ID); // groups is a "collection of lists" foreach (var sublist in groups) { … WebMar 2, 2024 · You're iterating through a list, and you want to find the index of the current item in the list? Just use a for loop instead of a foreach loop: C#. for ( int index = 0; index < sectionlist.Count; index++) { IGrouping section = sectionlist [index]; Console.WriteLine ( "The index of ' {0}' is {1}.", section.Key, index); ... ctifl balandran bellegarde