3

I am trying to create a histogram with ZedGraph.

The bars and data are all good, the only thing needed is my bars to be between the tics instead of directly on the tics.

Sample data:

1, 4
2, 8
3, 1

Means that I have:

4 items that are >= 0 and < 1
8 items that are >= 1 and < 2
1 item that is >= 2 and < 3

So currently my bars are of course appearing directly on the tics (x values) 1, 2 and 3.

But I would like to see:

  • the first bar between the tics 0 and 1,
  • the second bar between the tics 1 and 2 and
  • the third bar between the tics 2 and 3

What is the property to tweak in order to achieve that? I am currently looking in XAxis and XAxis.Scale, but I haven't found anything yet...

Bruno
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1 Answers1

3

You probably can't do it with normal BarItem. I use the BoxObj objects to create the histogram.

If histList is the PointPairList containing your pairs of histogram values (breakpoint and value) you can use:

for (int i = 0; i < histList.Count - 1; i++)
{
BoxObj box = new BoxObj(histList[i].X, histList[i].Y, histList[i + 1].X - histList[i].X, histList[i].Y);
box.IsClippedToChartRect = true;
box.Fill.Color = myColor;
pane.GraphObjList.Add(box);
}

Using the BoxObj you have full control on where the bar is located etc. More info in documentation

EDIT
Remember that when using BoxObj (or any GraphObj in general) the X and Y scales are not going to be set automatically. You need to set the scale ranges manually:

pane.XAxis.Scale.Min = ...
pane.XAxis.Scale.Max = ...
pane.YAxis.Scale.Min = ...
pane.YAxis.Scale.Max = ...
Gacek
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  • Hi, the chart starts zoomed up too much and many bars are outside of the visible area (zooming out we can see them). Would you be aware of how to fix it? – Bruno Oct 11 '10 at 15:40