C#：如何向列表中已存在的值添加新值<object> ?

Question

I have two lists including string values and percentage . I want to have duplicate string values once in my list and sum up their percentage. I don't know how can i access that specific place ( in reasonsName ) in the list ( reasonsPercent ).

List<object> reasonsPercent = new List<object>();
List<string> reasonsName = new List<string>();

foreach (var item in lvShareRateListSorted)
{

    string reasonName = "";
    reasonName = item.EventReasonTitle;

    if (reasonsName.Contains(reasonName))
    {
        // here i want to add item.TotalPercent to a TotalPercent of reasonName which exists in reasonsName
    }
    else
    {
        reasonsName.Add(reasonName);
        reasonsPercent.Add(item.TotalPercent);
    }
}

Answer 1

How about using dictionary ?

dictionary is Key-Value collection type

//You can add Content like 
dictionary.Add(key, value);
//remove
dictionary.Remove(key);
//access
dictionary[key]

        var nameAndPercentages = new Dictionary<string, List<int>>();

        foreach (var item in lvShareRateListSorted)
        {
            string reasonName = item.EventReasonTitle;
            
            //if the name is not present in dictionary add and initalize list for percentages
            if (!nameAndPercentages.ContainsKey(reasonName))
            {
                nameAndPercentages.Add(reasonName, new List<int>());
            }
            //add percentage value to list which initialized above
            nameAndPercentages[reasonName].Add(item.TotalPercent);
        }

        foreach (var nameAndPercentage in nameAndPercentages)
        {
            Console.WriteLine($"Name: {nameAndPercentage.Key}, Sum: {nameAndPercentage.Value.Sum()}");
            //Same with Console.WriteLine("Name: " + nameAndPercentage.Key + ", Sum: " + nameAndPercentage.Value.Sum());
        }

Answer 2

In this case, you can use a model for the list.

First of all, we declare a class:

public class Item
{
    public string ReasonTitle { get; set; }
    public float TotalPercent { get; set; }

}

next, declare a list of this class:

private static List<Item> items { get; set; } = new List<Item>();

and then, we need to find every item in the list. If it is found, we update it. If not, we add the item to the list:

public void AddOrEdit(Item  item)
{
    string reasonName = item.ReasonTitle;

    var searchResult = items.Find(x => x.ReasonTitle == reasonName);
    if (searchResult != null) // It is in the list
    {
        searchResult.TotalPercent += item.TotalPercent;
    }
    else
    {
        items.Add(item);
    }
}

Answer 3

if you want two lists and a percentage of float or double or int

var groupedList = lvShareRateListSorted
    .GroupBy(x => x.EventReasonTitle)
    .Select(x => new { EventReasonTitle = x.Key, TotalPercent= x.Sum(y => y.TotalPercent) });

reasonsPercent = groupedList.Select(x => x.TotalPercent).ToList();
reasonsName = groupedList.Select(x => x.EventReasonTitle).ToList();

or with a dictionary

var groupedList = lvShareRateListSorted
    .GroupBy(x => x.EventReasonTitle)
    .Select(x => new { EventReasonTitle = x.Key, TotalPercent= x.Sum(y => y.TotalPercent) });    

var dictionary = groupedList.ToDictionary(x => x.EventReasonTitle, y => y.TotalPercent);