exposing the wavetrend indicator for strategy builder

[bltdavid]

I assume Chelsea has advised you that only Plots are 'exposed' for
use in Strategy Builder.

Which means, that it's very important to understand how you intend
for this 'reversal' variable to be employed inside Strategy Builder.

Perhaps what you're wanting to do is not possible?

[ezrollin]

I assume Chelsea has advised you that only Plots are 'exposed' for
use in Strategy Builder.

I've been told so many times by everyone.

May I suggest you describe in very specific terms exactly what
you're wanting to do?

Do you really want every bar to have it's own 'reversal' value
associated with it? Or do you want a single global 'reversal'
setting, like a knob, that the user can turn on and off?

I want to tell strategy builder what the indicator is doing.
In this case, the topic of this thread is the wavetrend indicator.
If theres a wavetrend crossover either way, I want the strategy to react to it.

[bltdavid]

Can you post a link to the wavetrend indicator?

[ezrollin]

https://ninjatraderecosystem.com/user-app-share-download/wave-trend-oscillator-2/

I'm asking for any indicator, not just that one.
I want to have the ability to modify other indicators so I can use them with strategy builder or coding strategies manually

[NinjaTrader_ChelseaB]

Hello ezrollin,

The code you have:
public Series<bool> reversal

Will not work. This is a public Series<bool> not a public Series<double>.

A bools series is not a plot series. You need to be returning the Values[plot index] with a public Series<double>.

Its not going to work until you have exactly what is shown in the example I provided you.

Please try returning Values[0] with a public Series<double>.

I am copying and pasting the code from my example, as I do not believe you have looked at it.

[Browsable(false)]
[XmlIgnore]
public Series<double> SignalPlot
{
get { return Values[0]; }
}

[ezrollin]

OK, this is what I have now:

public Series<double> reversal;   // in parameters

reversal = new Series<double>(this);     // in setdefaults

reversal[0]    = 1;     //true
reversal[0]    = 0;    //false

[Browsable(false)]        // in properties
[XmlIgnore]
public Series<double> Reversal
{
get { return reversal[0]; }
}

I tried using "reversal" instead of "values" because I didnt want values to conflict with anything else in the script but it should probably be "values" huh?
I didnt add an ADDPLOT because you didnt tell me to.
What am I doing wrong? thanks

[ezrollin]

I'm getting a "cannot convert double to series double" on that property ( get {return reversal[0]; )

[NinjaTrader_Jesse]

Hello ezrollin,

One item is that your backing variable should be private, this is currently exposed which will have errors:

public Series<double> reversal; // in parameters

that should be

private Series<double> reversal; // in parameters

The public property is also returning a series not a single double value so you just need to pass the variable that is a Series<double> object:

[Browsable(false)] // in properties
[XmlIgnore]
public Series<double> Reversal
{
    get { return reversal; }
}

[ezrollin]

That got it to show up in the strategy.
I cant get the strategy to run though. I'm on playback, I click on the radio button to enable it but it immediately unchecks it.
I get this error in the Output: "Strategy 'Scalp': Error on calling 'OnBarUpdate' method on bar 40: Object reference not set to an instance of an object."
I've made NO changes to the OnBarUpdate section...
Also its been hard to get the indicator to show its original plots.
I even copied over a fresh install manually and reentered our edits.

[NinjaTrader_ChelseaB]

Hello ezrollin,

Object reference not set to instance of an object means there was a variable with a null value.

https://ninjatrader.com/support/helpGuides/nt8/checking_for_null_references.htm

What variable is causing the error? What method is this being used from?

[ezrollin]

it only happens when I add my added reversal


private Series<double> reversal;

[Browsable(false)] // in properties [XmlIgnore] public Series<double> Reversal { get { return reversal; } }

SO I think I need to assign a value to the reversal somewhere other than in my IF THEN condition?

[NinjaTrader_ChelseaB]

Hello ezrollin,

Testing this does not cause an error on my end. Are you certain this is the code causing the error?

If this code is commented out, does the error stop?

[ezrollin]

Are you certain this is the code causing the error?
If this code is commented out, does the error stop?

it only happens when I add my added reversal

Yes.
The code you sent me allowed me to figure it out.
I didnt have that stuff in the Data Loaded section. I didnt have a data loaded section at all
I noticed it doesnt have anything about a plot?
Thanks

[NinjaTrader_ChelseaB]

Hello ezrollin,

This is a custom series. Which has to be instantiated in State.DataLoaded as specified in the help guide.

Returning a plot series does not require making a custom series as shown in post# 20.

[ezrollin]

Hey Chelsea,
Thanks for your script. It helped me figure out how to expose it but I guess its not returning the variable correctly.
I sent my script to Paul and he said I have to use AddPlot and add an output in region properties. (if I added a property, I'm not sure I would be doing it right)
Can you update your example to show that please?
Thanks,
ezrollin

This is what he said:

The issue here is that the Strategy builder can only work with a plot.

It will not work with an exposed double variable.

You would need to add a plot using AddPlot(). You can set the plot as a transparent plot so it is not visible on the chart but will still provide a value to the strategy builder.

You would assign your values in the same way that you have with the exposed double series. You will also need to add an output for it in region Properties, just like the Up[Trend and DownTrend plots, as you are adding a third plot then you would be using Values[2].