Using once custom indicator inside other my indicator

[Globus000]

Hello
I've got one custom indicator - USCPIMonthly
The code looks like this:

protected override void OnBarUpdate()
        {
            DateTime dtNow = Time[0];
			int index = _helper.GetDateIndex(dtNow);
			if(index != null)
			{
				for(int i = 0; i < _helper.Series.Count; ++i)
				{
					Values[i].Set( _helper.Series[i].Values[index] );
				}
			}
        }

- so nothing special here - just getting the value for each date and setting to indicator

Here I'm trying to reference it in another my indicator

protected override void OnBarUpdate()
        {
			if(USCPIMonthly().Count > 0)
			{
				double currCpi = USCPIMonthly()[0];
				Print("USCPIMonthly()[0] = " + currCpi);
				double currCpiPrev = USCPIMonthly()[1]; // EXCEPTION HERE!
				Print("USCPIMonthly()[1] = " + currCpiPrev);
				
				Values[0].Set( (currCpi - currCpiPrev)/currCpiPrev * 100 );
				
			}
        }

The problem is that I can only reference the first value - but when I'm trying to get the previous one I'm getting an exception that array is out of range etc.
My question: why I cannot get the indicator value for the previous bar?

[NinjaTrader_ChelseaB]

Hello Globus000,

If in the USCPIMonthly indicator there is a plot added with the Add() call in Initialize, this plot will have a value for each bar. If you call a bar that doesn't have a value set, the close price should be returned instead. (.ContainsValue(int barsAgo) is used to check if there was a value set or not)
http://ninjatrader.com/support/helpG...ries_class.htm


Was there a plot added to the USCPIMonthly indicator in Initialize that is being set?
Is there an update being called that would cause that plot to recalculate when called for previous bars?

(As an example try calling SMA(14)[1]. This script should be able to return the previous bar without issue.)

[Globus000]

Yes, the plot was added on initialize, but how to call the update in order to recalc the indicator and get values for barsAgo?

[NinjaTrader_ChelseaB]

Hello Globus000,

After each bar is set in OnBarUpdate, this does not get unset automatically. The data series will continue to hold the set value for each bar historically. You will not have to update the script to get historical values.

I am asking if there is an update that might be unsetting these values, so that I may direct you to removing this update which would be causing this issue.

May I confirm that you have tried calling the SMA(14)[1] and this did not work as expected?

[Globus000]

Hello

Sorry, for responding with delay.
Regarding SMA - I'm facing the same error - here is the code:

protected override void OnBarUpdate()
{
if(USCPIMonthly().Count > 0)
{
double currCpi = USCPIMonthly()[0];
Print("USCPIMonthly()[0] = " + currCpi);
double prevSma = SMA(14)[1];
Print("SMA(14)[1] = " + prevSma);
double currCpiPrev = USCPIMonthly()[1];
Print("USCPIMonthly()[1] = " + currCpiPrev);

Values[0].Set( (currCpi - currCpiPrev)/currCpiPrev * 100 );

}
}

And here is the output:

USCPIMonthly()[0] = 237.423
Error on calling 'OnBarUpdate' method for indicator 'USCPIPercMonthly' on bar 0: You are accessing an index with a value that is invalid since its out of range. I.E. accessing a series [barsAgo] with a value of 5 when there are only 4 bars on the chart.

[NinjaTrader_ChelseaB]

Hello Globus000,

To check one bar ago, there must be a bar one bar ago.

Try:

if (CurrentBar > 0)
{
Print(SMA(14)[1]);
}

Does this give you an error?

[Globus000]

Hi Chelsea,

Yes, you're absolutely right - I missed this. Now it works fine. Thanks!