在 C# 中的另一个列表中搜索列表中的项目

Question

I want to match any string items in the list with substring items in another list, then put substring and repetition in the dictionary without for loop because the substring list contains 24345000 cells.

 string[] folders = Directory.GetDirectories(@"..\Raw Data", "*");
 Dictionary<string, int> freq = new Dictionary<string, int>();
 var letters= File.ReadAllLines(@"..\letters.txt").ToList();
 foreach (string folder in folders)
        {
            string name_folder = Path.GetFileName(folder);

            string[] N_F = Directory.GetFiles(@"..\items\" + folder, "*.txt");
            foreach (string f in N_F)
            {
                List<string> s = File.ReadAllText(f).Split(' ').ToList();
                s.RemoveAll(string.IsNullOrWhiteSpace);
                foreach(string t in letters)
                    if(s.Contains(t))
                if (freq.ContainsKey(t))
                        freq[t]++;
                    else
                        freq[t] = 1;
            }
}

Answer 1

You are looking for a way to search count of occurrence of words from a list in another list.

// Sample Data 
var letters = new string[] { "Apple", "Orange", "Mango", "Cherry" };
var masterList = new string[] 
                { "Apple", "Tea", "Mango", "Apple", "Wheat", "Mango",
                  "Bread", "Orange", "Mango", "Apple", "Orange", "Mango",
                  "Apple", "Bread", "Mango", "Apple", "Bread", "Tea"
                }; 

You can try:

var freq = words.Select(w => new { Word = w, Count = masterList.Count(m => m == w) })
                              .ToList();

freq will contain:

Word = Apple    Count = 5
Word = Orange    Count = 2
Word = Mango    Count = 5
Word = Cherry    Count = 0