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How to get filtered item by value index in C# Dictionary? – Asp.net

I am trying to write a method which should return the item value based on value index and condition.

For example, in the below, if I pass index value as 0, it should return keys and first value from integer array which is not having value 5.

public static Dictionary<string, int[]> _dict = new Dictionary<string, int[]>()
    {
        {"A", [1,0,3] },
        {"B", [5,1,5] },
        {"C", [7,11,5] },
        {"D", [0,1,5]},
        {"E", [14,0,5] },
        {"F", [5,1,5] }
    };

Expected O/P:

if I pass index value 0, and condition as != 5 then O/P should be

    {
        {"A", 1 },
        {"C", 7 },
        {"D", 0 },
        {"E", 14}
    };
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2

Answers


  1. 0

    You could achieve this in two steps:

    1. Get those items that do not start with 5
    var res = _dict.Where(a => a.Value[0] !=5);
    1. Then populate a new Dictionary with the remaining keys and the first entry in their integer array
    foreach(KeyValuePair<string,int[]> keyValuePair in res)
{
    result.Add(keyValuePair.Key, keyValuePair.Value[0]);
}

    or using LINQ

    result = res.ToDictionary(keyValue => keyValue.Key, keyValue => keyValue.Value[valueIndex]);

    Complete code would look something like

    public static Dictionary<string, int[]> _dict = new Dictionary<string, int[]>()
{
    {"A", new int[] {1,0,3 } },
    {"B", new int[] {5,1,5} },
    {"C", new int[] {7,11,5} },
    {"D", new int[] {0,1,5}},
    {"E", new int[] {14,0,5} },
    {"F", new int[] {5,1,5} }
};

static Dictionary<string, int> GetResult(int valueIndex, Func<KeyValuePair<string, int[]>, bool> predicate) =>
            _dict.Where(predicate)
                 .ToDictionary(keyValue => keyValue.Key, keyValue => keyValue.Value[valueIndex]);

    GetResult(valueIndex: 0, predicate: a => a.Value[0] != 5) then gives the result you want

    {
    {"A", 1 },
    {"C", 7 },
    {"D", 0 },
    {"E", 14}
};
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  2. 0

    One line code using LINQ

    var result = _dict.Where(x => x.Value[0] != 5).ToDictionary(x => x.Key, y => y.Value[0]);
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