[RESOLVED] getting an average in a datagridview

[limelight]

Hi all
Below I have code to sum up a list of numbers in a specific column in my datagridview,but is there a way I can take the first five numbers of the column and find the average figure,and then place that average figure into a text box on my form.

 Private Sub Button7_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button7.Click
        Dim sum As Double = 0
        Dim i As Single
        For i = 0 To DataGridView1.RowCount - 1
            sum +=
            DataGridView1.Rows(i).Cells("examfigs").Value()
        Next
        TextBox1.Text = sum      

    End Sub

kind regards
al

[jmcilhinney]

I don't think that you have really thought this through. You have a loop that goes from 0 to the index of the last row in the grid. If you only want to use five rows then does it not make sense to change the upper limit of the lop to the index of the fifth row in the grid, i.e. 4?

[limelight]

Hi,
Thanks for your reply.I see what you mean but what code would I use to actually average the numbers up.
Kind regards
al

[jmcilhinney]

Again, think it through. We all learned how to calculate an average in school. You simply add the values together and divide by the number of values. You're already doing the first part.

[limelight]

Hi JM,
got it I think
This works but does it look OK to an expert like yourself.Many thanks for your suggestions encouragement.

Private Sub Button7_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button7.Click
        Dim sum As Double = 0
        Dim i As Single
        For i = 1 to 5
            sum +=
            DataGridView1.Rows(i).Cells("examfigs").Value()
        Next
        TextBox1.Text = sum      
        TextBox1.Text = sum/5
    End Sub

[jmcilhinney]

If 'i' is being used to store Integer values then why is it declared as type Single?

You were starting your loop counter at 0 before and you have now changed it to 1. Why is that? Do you want to start at the second row?

There's no point setting the Text of the TextBox to 'sum' if what you actually want it set to is 'sum/5' and that's what you actually set it to immediately afterwards. If you want a wall painted blue, would you paint it red first and then immediately paint it blue over the top?

[limelight]

Hi Jm,
Thanks for the reply.Starting the loop at zero only took the first 4 numbers in,1 to 5 took the five numbers in.Good point about setting the sum.I never thought of that.Do you mean like this?

Private Sub Button7_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button7.Click
        Dim sum As Double = 0
        Dim i As Single
        For i = 1 to 5
            sum +=
            DataGridView1.Rows(i).Cells("examfigs").Value()
        Next
        TextBox1.Text = sum/5      
       
    End Sub

What would you set the i int to, perhaps a double.?

Kind Regards
albert

[bmwpete]

If you look at the DataGridView1.RowCount value you will note it is an integer. You would use an integer to iterate through collections/arrays like this and which all are zero index based i.e. the first index position starts at 0. In your case the first row will be 0.

You can include the count variable in the construction of the for/loop like this,

For i as integer = 0 to 4 ' process the first 5 rows 
sum +=  DataGridView1.Rows(i).Cells("examfigs").Value()  ' Do something with each row
Next

[ChrisE]

Hi,

if you use a Datatable, you can use this...

I want to get the avg. Frachtkosten from my Datatable loaded to my Datagridview

the Function..

 Public Function Mittelwert(ByVal TB As DataTable) As Single
        Dim SumVal As Single = 0
        For Each Rw As DataRow In TB.Rows
            SumVal += Convert.ToSingle(Rw("Frachtkosten"))
        Next
        Return SumVal / TB.Rows.Count
    End Function

then to call it...

 
MsgBox(Mittelwert(objDataTable))

regards
Chris

[kpmc]

Hi,

if you use a Datatable, you can use this...

I want to get the avg. Frachtkosten from my Datatable loaded to my Datagridview

the Function..

 Public Function Mittelwert(ByVal TB As DataTable) As Single
        Dim SumVal As Single = 0
        For Each Rw As DataRow In TB.Rows
            SumVal += Convert.ToSingle(Rw("Frachtkosten"))
        Next
        Return SumVal / TB.Rows.Count
    End Function

then to call it...

 
MsgBox(Mittelwert(objDataTable))

regards
Chris

I would opt for this method, however I would build a condition to remove NULL values from the AVG. I am not sure what the default behavior is when getting average via aggregate avg function from sql or datacolumn expression, but I am thinking NULLS are not included in the results. I could be wrong