General Question about Charts (1 Viewer)

[zooropa67]

I've got a chart that i want to display some Yield data
(class = MSGraph.Chart.8)
Eventually this could run into hundreds if not thousands of values. That would be too many points to display at one time. I was amazed to find out (correct me if i'm wrong) that there is no horizontal scrollbar built into the chart control to allow you to scroll back through the plotted data. I probably wouldn't want any more than 30 data points showing at a time as i want to be able to see the x-axis label values for every point. I did find a scrollbar component that i guess could be used to requery the tables and update the chart on the fly but that seems like a very inefficient way to do it and i can't find any source code to achieve this. Could anyone give me any pointers? It feels like i'm missing the obvious. Surely a basic requirement of a line chart is to be able to scroll back through it???

 

[Privateer]

You can build a form in landscape and get about 22 inches out of it. The horizontal scroll bar is on the form. So if the graph is twenty inches wide and the form is only eight inches wide, displaying eight inches of the graph, as you move left or right you will see the other sections of the graph.

 

[ChrisO]

As far as I know a chart can not have more than about 4000 data points. However, it is pointless in trying to display more than one point per pixel.

The largest dataset I’ve had to deal with was 35 samples every 30 seconds for one month. That comes to around 3,000,000 records. So even with a scroll bar it would become impossible to scroll with sufficient precision to see each point.

So other methods need to be employed. That involves the X axis jumping back and forth by whole pages of data, predefined blocks of data and jogging the X axis by single point if necessary. You may also want to slide across the surface of the chart to produce a limited zoom of the dataset in another chart. You may also want to produce Reports based on the selected dataset.

The simplest way to do this is to modify the SQL feeding the chart(s).

There is an Access 2003 demo attached which uses date/time as the X axis. It uses a double data type, rather than a date/time data type, because Afrikaans in regional settings caused a problem.

When started, the demo will generate 2880 samples for testing. I hope it still works in your version of Access.

Chris.