Group users by age for stats

Question

first thing first my question is very similar to this one. In fact, it's the same thing, except that I need to group every user like this below:

1. Everyone under 12 (exclusive)
2. Then, from 12 - 19
3. Then, from 20 - 29
4. ...
5. More than 80 (inclusive)

Based on the answer from dasblinkenlight in the other question, I was able to do:

var ageStats = vModel
                          .GroupBy(l => 10 * (l.Age / 10))
                          .OrderBy(x => x.Key)
                          .Select(g => new
                          {
                              Name = g.Key,
                              Count = g.Select(l => l.Age).Count()
                          }).ToList();

For a result set of :

1. 0-9
2. 10-19
3. 20-29
4. ...

So what should I do to accomplish the pattern I have to ?

Thank you very much !!

Answer 1

var ages = new[] { 12, 19, 29, 80 };

var grouped = ages.Select(r => new {
                Name = r,
                Count = vModel.Count(x => x.Age >= r)
            });

Answer 2

try this, but i don't know the performance

var ages = new int[12, 19, 29, 80];
var func = new Func<int, int>(a=>{

    for(var i = 0; i<ages.Length; i++){
        if(a<ages[i])
            continue;
        return i;
    }
    return 0;
});
vModel.GroupBy(m=>func(m.Age))....

Answer 3

You could use approach mentioned here and use this code:

var ages = new List<int> { 12, 19, 29, 39, 49, 59, 69, 80, int.MaxValue};
var categories = vModel.GroupBy(item => ages.FirstOrDefault(ceil => ceil >= item));