Comparing the difference between the values ​​in the dictionary

Question

I have a Dictionary<string, float> and you want to select KeyValuePairs from where the difference between the float values ​​is less than a certain amount.

This is a dictionary:

 Dictionary<string, float> heights = new Dictionary<string, float> (); 

sample entries:

 "first", 61.456 "second", 80.567 "third", 62.456 "4", 59.988 "5", 90.34 "6", 82.123 

I need these elements with a small difference in their values, for example. “first”, “third” and “4” in the list or something similar. difference is the set value of the float, say 3.5

Is it possible to achieve this Linq?

I tried to do this with loops, but it really gets messy ...

Answer 1

You can create your own method that searches for close values ​​and takes two parameters: a dictionary that contains values ​​and float, which are used to store the maximum search range:

  static Dictionary<string, float> FindRange(Dictionary<string, float> dict, float precision) { Dictionary<string, float> temp = new Dictionary<string, float>(); List<int> counter = new int[dict.Count].ToList(); float[] values = dict.Values.ToArray(); for (int i = 0; i < values.Length; i++) for (int i2 = 0; i2 < values.Length; i2++) if (i2 != i && Math.Abs(values[i] - values[i2]) < precision) counter[i]++; for (int i = 0; i < values.Length; i++) if (Math.Abs(values[i] - values[counter.IndexOf(counter.Max())]) < precision) temp.Add(dict.FirstOrDefault(kv => kv.Value == values[i]).Key, values[i]); return temp; } 

Usage example:

 static void Main() { Dictionary<string, float> heights = new Dictionary<string, float>() { {"first", 61.456f}, {"second", 80.567f}, {"third", 62.456f}, {"4", 59.988f}, {"5", 90.34f}, {"6", 82.123f} }; // returns max sequence of elements with difference less than 3f var newDict = FindRange(heights, 3f); foreach (var item in newDict) { Console.WriteLine(item.Key + " " + item.Value); } } 

Exit:

 first 61,456 third 62,456 4 59,988 

Answer 2

You can sort the records by value first, and then it will be easier to compare the neighboring records.

 var list = heights.ToList(); list.Sort((a,b) => {return a.Value.CompareTo(b.Value);}); bool first = true; for (int i = 1; i < list.Count; ++i) { if (Math.Abs(list[i-1].Value - list[i].Value) < threshold) { if (first) { first = false; Console.WriteLine(list[i-1]); } Console.WriteLine(list[i]); } } 

A working example on dotnetfiddle is here .

Answer 3

Sort of:

 List<KeyValuePair<string,float>> matching = new List<KeyValuePair<string,float>>(); int i = 0; var all = _dict.Select(kvp => kvp).ToList().OrderBy(kvp => kvp.Value); all.ForEach(kvp => { if(i < all.Count() - 1 && Math.Abs(all[i+1].Value - kvp.Value) < threshhold) { matching.Add(kvp); if(i == all.Count() - 1) matching.add(all[i+1]); // Need to manually add the final entry if it a match } i++; });