How to return the items that are difference in TWO DICTIONARIES (DICTIONARY<STRING, LIST<Runs>>) in c#?

Question

Hello,

I have 2 dictionaries -- DICTIONARY<STRING, LIST<Details>>

internal class Details
        {
            
            public DateTime StartDate { get; set; }
            public DateTime EndDate { get; set; }
            public string Gender{ get; set; }
  }

old dictionary:

{"Mary", [{"2022-10-30", "2022-11-30", "F"}]}

{"Peter", [{"2022-11-30", "2022-12-30", "M"}]}

new dictionary:

{"Mary", [{"2022-10-30", "2022-12-30", "F"}]}

{"Peter", [{"2022-11-30", "2022-12-30", "M"}]}

As the example above, I want to return the item/list, as "EndDate" of the "Mary" in the new dictionary is different.

Is there a way to do it in C#? Please note the dictionary would be very large.

Thanks

Answer 1

Hi @Wanda , Welcome to Microsoft Q&A,

You can use LinQ to write comparison code neatly and quickly.

as follows:

using System;
using System.Collections.Generic;
using System.Linq;

namespace _11_2_x
{
    internal class Details
    {
        public DateTime StartDate { get; set; }
        public DateTime EndDate { get; set; }
        public string Gender { get; set; }
    }
    internal class Program
    {
        static void Main(string[] args)
        {
            Dictionary<string, List<Details>> oldDictionary = new Dictionary<string, List<Details>>();
            Dictionary<string, List<Details>> newDictionary = new Dictionary<string, List<Details>>();

            // Initialize old and new dictionaries with your data

            // Example:
            oldDictionary["Mary"] = new List<Details>
        {
            new Details { StartDate = DateTime.Parse("2022-10-30"), EndDate = DateTime.Parse("2022-11-30"), Gender = "F" }
        };
            oldDictionary["Peter"] = new List<Details>
        {
            new Details { StartDate = DateTime.Parse("2022-11-30"), EndDate = DateTime.Parse("2022-12-30"), Gender = "M" }
        };

            newDictionary["Mary"] = new List<Details>
        {
            new Details { StartDate = DateTime.Parse("2022-10-30"), EndDate = DateTime.Parse("2022-12-30"), Gender = "F" }
        };
            newDictionary["Peter"] = new List<Details>
        {
            new Details { StartDate = DateTime.Parse("2022-11-30"), EndDate = DateTime.Parse("2022-12-30"), Gender = "M" }
        };


            var differentItems = newDictionary
            .Where(newKV =>
                oldDictionary.TryGetValue(newKV.Key, out var oldDetailsList) &&
                newKV.Value.Count == oldDetailsList.Count &&
                newKV.Value.Zip(oldDetailsList, (newDetails, oldDetails) => new { New = newDetails, Old = oldDetails })
                    .Any(pair => pair.New.StartDate == pair.Old.StartDate && pair.New.EndDate != pair.Old.EndDate))
            .ToDictionary(kv => kv.Key, kv => kv.Value);

            foreach (var kvp in differentItems)
            {
                Console.WriteLine($"Key: {kvp.Key} has different EndDates in newDictionary:");
                foreach (var detail in kvp.Value)
                {
                    Console.WriteLine($"StartDate: {detail.StartDate}, EndDate: {detail.EndDate}, Gender: {detail.Gender}");
                }
            }
            Console.ReadLine();
        }
    }
}

Best Regards,

Jiale

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