C# 计数出现次数 dataGridView

Question

I'm trying to count the occurrences of some given numbers as the picture shows.

Giving 5 numbers to the program i want it to output

Número - Frequência R - Frequência A (1 - 2 - 0.4) (2 - 1 - 0.2) (3 - 2 - 0.4)

Frequência R is the number of times that the number appears.

My problem is counting the occurrences of the numbers and setting up the cells with the correct value.

Frequência A is the same since I need the amount of times it appears to divide by the total number of rows.

How would I do this?

Answer 1

Assuming dataGridView1 is bound to a DataTable ( dt in my example), or can be, you can do some Linq kung fu to project another collection that can be bound to the second grid:

var projection = dt.AsEnumerable()
    .Select(n => n.Field<decimal>("Nome"))
    .GroupBy(d => d)
    .Select(d => new { Numero = d.Key, FrequenciaR = d.Count(), FrequenciaA = (decimal)d.Count() / dt.Rows.Count })
    .ToList();

This code gets the list of Nomes and groups them by their value. At this point you will have 3 IGroupings. Then Select projects the key of the group (the number), the count of how many are in the group and finally the number divided by the number of rows in the table.

projection is a list you can bind to the second data grid. You could of course project into a class type you define.

UPDATE

You can work directly with the gridview rows though it is a bit more awkward. I encourage you to consider reading up on data binding collections, but try this which does the same as my first example, it just does it against the DataGridViewRowCollection instead:

var projection2 = dataGridView1.Rows.Cast<DataGridViewRow>()
    .Where(dgvr => dgvr.Cells[0].Value != null) // don't count blank rows
    .Select(dgvr => (decimal)dgvr.Cells[0].Value )
    .GroupBy(d => d)
    .Select(d => new { Numero = d.Key, FrequenciaR = d.Count(), FrequenciaA = (decimal)d.Count() / (dataGridView1.Rows.Count - 1) }) // count - 1 to exclude last edit row
    .ToList();

If you have LINQPad you can run my example