Finding Y value from X value in MSChart Series - mschart

Question

I have created a Line chart using MSChart 2008.I have Dates on the x axis and Double values on y axis.Now I need to find Y value on Todays Date(Which will be my x value)..Can anybody help me to achieve this.
Thanks

Answer 1

I use a similar approach to this with cursors: I wanted to find the closest record to where the vertical cursor was added and show the value for that (as opposed to the value of the cursor coordinates):
If you swap out e.NewPosition with your query value (eg. today's date), the code should do what you want.
// Cursor Position Changing Event
private void chart1_CursorPositionChanged(object sender, CursorEventArgs e)
{
//Get the nearest record and use its X value as the position
double coercedPosition = chart1.Series[0].Points.Aggregate((x, y) => Math.Abs(x.XValue - e.NewPosition) < Math.Abs(y.XValue - e.NewPosition) ? x : y).XValue;
//Set cursor to the coerced position
chart1.ChartAreas[0].CursorX.Position = coercedPosition;
SetPosition(e.Axis, coercedPosition);
}
// Update the labels with the values at the indicated position
private void SetPosition(Axis axis, double position)
{
if (double.IsNaN(position))
return;
if (axis.AxisName == AxisName.X)
{
//Get the value at the position
DateTime dt = DateTime.FromOADate(position);
//set the timestamp label
lbl_CursorTimestampValue.Text = dt.ToString();
//get the point at that timestamp (x value)
var point = chart1.Series[0].Points.FindByValue(position, "X");
//set the y value label
lbl_CursorYValue.Text = point.IsEmpty == true ? "--" : point.YValues[0].ToString();
}
}
Also note that if you will want to convert your DateTime to an OA value:
double yourOADate = yourDateTime.ToOADate();