Help!!! array.

[nickwrs]

Okay here is how it goes,

I have a data tracking program, and it records data to a file, I have decided to allow an option of viewing this data via ms chart during the data tracking.

But the amount of data is changing and I only know how to add data to mschart via an array, but since I have an undefined amount of data, I can't very well use an array,

any suggestions or is there a better way to do this?

I had considered using microsoft excel, but I don't know how to use it to make a chart, and or how to add data to it infinitely.

Please help.


Nicholas spencer

[MartinLiss]

I may not completely understand your problem, but what I would do is to first find out how may records are going to be added to the array, dimension the array accordingly, and then interface with mschart (which I've never done).

[nickwrs]

That is the point, I don't know the eventual amount of records, there for I cannot dimension an array.

I am looking for another solution.

[MartinLiss]

Why don't you know the number of records? Could you create a trailer record for the file and write the number of records to it? Then when you open the file, read the last record first and then dimension the array. If I'm still off the mark, email me and I'd be happy to "talk" with you about it.

[PaulLewis]

Is the plan to have the chart update dynamically while the data is "coming in" so to speak?

Or will the user have to hit a refresh button to get the chart to update?

The data being tracked is not recorded, only the tracking information is this correct?

ON your comment about only knowing how to add data via an array, I took an example out of the help for MS Chart and slightly ammended it to give the following example.

Private Sub Command2_Click()
  With MSChart1
    Dim column, row, index1, index2, index3, index4 As Integer
    .RowCount = .RowCount + 1
    .row = .RowCount
    .Data = .RowCount * 7.5
  End With
End Sub
Private Sub Command1_Click()
  With MSChart1
    ' Displays a 3d chart with 8 columns and 8 rows
    ' data.
    Dim column, row, index1, index2, index3, index4 As Integer
    .chartType = VtChChartType3dBar
    .ColumnCount = 1
    .RowCount = 8
    For column = 1 To 1
      For row = 1 To 8
        .column = column
        .row = row
        .Data = row * 10
      Next row
    Next column
    ' Use the chart as the backdrop of the legend.
    .ShowLegend = True
    .SelectPart VtChPartTypePlot, index1, index2, index3, index4
    .EditCopy
    .SelectPart VtChPartTypeLegend, index1, index2, index3, index4
    .EditPaste
  End With
End Sub

Please don't mention the variable names and the pointless for next loop - as I said I ripped it out of the help and used it more or less as is.

If you create a form with an MS Chart, Command1 and Command2, try hitting command1 which will update the chart with some data.

Then each time you hit command2, the data will get a new row added.

Obviously you would want this to be done on a timer event to give the effect of real time updates...

Does this help in any way?

Regards
Paul Lewis

[nickwrs]

That's sounds reasonable, I'll try it!! :-)

[Guv]

I do not fully understand what you are doing, but do you know about Redim?

Redim allows you to change the dimensions of an array. It has an option which allows making an array larger without losing data already in the array.

Perhaps you could work with an array that you Redim as required, and an array into which you read new data. Read more data into second array, Redim the other array, copy data from second to first. Repeat as often as required.

I copied the following from my MSDN Library documentation.

To create a dynamic array

Declare the array with a Public statement (if you want the array to be public) or Dim statement at the module level (if you want the array to be module level), or a Static or Dim statement in a procedure (if you want the array to be local). You declare the array as dynamic by giving it an empty dimension list.
Dim DynArray()

Allocate the actual number of elements with a ReDim statement.
ReDim DynArray(X + 1)

The ReDim statement can appear only in a procedure. Unlike the Dim and Static statements, ReDim is an executable statement — it makes the application carry out an action at run time.

ReDim [Preserve] varname(subscripts)

Redim uses sames syntax as Dim. It has a "Preserve" option if array contains data when Redim is executed.

Hope the above helps.