Unlike statements

[turbofib]

Example

-----------
public class P1: Indicator ========> there is an indicator

.............
'instruction '
............
------------

What is the difference between

1)

public class USingP1: Strategy

Private P1 var1; ====>I declare a variable of the type above


2)

public class USingP1: Strategy

Add(P1(var1,var2)); ====>I use a variable of the type above




IN both statements recall an earlier indicator ... but which is the difference?

[NinjaTrader_Bertrand]

turbofib, I'm sorry - you mean adding the indicator in for display via the Add()?

var1 and var2 would be part of the indicator constructor needed for deciding which parameters to use for the call.

Case 1 is also used to assign the indicator to a variable to be able to call it easier and more efficiently, since you just refer to the var name instead of calling the full overload again in your code.

[turbofib]

ok
but Why when i call the indicator and pass the value of the variables...it give me error :

Private P1 var1;


Print(var1(Input,2).Num);
// ( "2 " is variable passed because the indicator accepts 1 inputs numerical )
// (Num is field output)

Error:the name "var1" does not exist in the current context

[NinjaTrader_Bertrand]

Looks to me like you never assign the indicator to your variable?

Here's a quick example with a basic SMA -

public class Test : Indicator
    {        
        private SMA sma1;
       
        protected override void Initialize()
        {
            Overlay				= true;
        }
				
        protected override void OnBarUpdate()
        {
            if (CurrentBar == 0)
	  sma1 = SMA(Close, 20);
			
            Value.Set(sma1[0]);
        }
        
    }

[turbofib]

IN A NUTSHELL:

double g1=0;
g1=P1(2).Num;
Print(g1); ==========================>is correct..
it run correctly

Private P1 var1;
Print(var1(2).Num; ============> is not correct...give me an error

[turbofib]

OK ...i understand my error..

Thanks you

[turbofib]

Looks to me like you never assign the indicator to your variable?

Here's a quick example with a basic SMA -

public class Test : Indicator
    {        
        private SMA sma1;
       
        protected override void Initialize()
        {
            Overlay                = true;
        }
                
        protected override void OnBarUpdate()
        {
            if (CurrentBar == 0)
      sma1 = SMA(Close, 20);
            
            Value.Set(sma1[0]);
        }
        
    }

i ask a question :
when the following instruction "sma1 = SMA(Close, 20);" i can put it in "Initialize" instead in Onbarupdate?

what changes? I have examples where 'indifferent where I put it .. gives me the same result

I understand if I put it in Initialize is executed only 1 time ..

In onbarupdate runs in each bar---then is more efficient algorithm in the first case

Is correct?



I

[NinjaTrader_ChelseaB]

Hi turbofib,

It looks like the first bar of historical data is available at startup.

I think adding that to OnStartUp() would be a better idea.


Also, you are using a period of 20 but on the first bar. That would be the same as just using the Close price as there is only going to be one bar in the dataseries..

[turbofib]

with OnStartUp() do you mean
OnBarUpdate()?


i dont' undertand you last sentence:
"Also, you are using a period of 20 but on the first bar. That would be the same as just using the Close price as there is only going to be one bar in the dataseries.. "

you can explain it better?

[NinjaTrader_ChelseaB]

Hello turbofib,

Below is a link to the help guide on OnStartUp().
http://www.ninjatrader.com/support/h.../onstartup.htm


The SMA is an average (Simple Moving Average). The period will be the number of bars used for the average. So if the period is 20, 20 bars should be used for the average. That is if there are 20 bars of data.

If you call SMA(Close, 20)[0] with only 1 bar of data (as in CurrentBar is 0 like at startup) then only 1 bar will be used for the average. In other words it will not really be an average. If you are doing this at startup SMA(Close, 20)[0] will always equal Close[0].

Try printing the following in OnBarUpdate():
if(CurrentBar == 0)
Print(SMA(Close, 20)[0]+" - "+Close[0]);

[turbofib]

yes...i try it and SMA(Close, 20)[0=Close[0]

but i don't understand that :

"
OnstartUp :

This method is called only once immediately prior to the start of your script processing its logic in OnBarUpdate(),
"

But the instruction of the plot is call to every candle ... not just the first candle ...
Then I see him more logical in
OnBarUpdate()


or not?

[koganam]

i ask a question :
when the following instruction "sma1 = SMA(Close, 20);" i can put it in "Initialize" instead in Onbarupdate?

what changes? I have examples where 'indifferent where I put it .. gives me the same result

I understand if I put it in Initialize is executed only 1 time ..

In onbarupdate runs in each bar---then is more efficient algorithm in the first case

Is correct?



I

You declared your named instance of the SMA. You now need to intialize it ONCE. If you put the initialization statement in OBU, you are reinitializing your named instance each time the barUpdate event is handled. You need to initialize your named instance in either Initialize(), OnStartUp(), or delimited to (CurrrentBar == 0).

[NinjaTrader_ChelseaB]

Hi turbofib,

i ask a question :
when the following instruction "sma1 = SMA(Close, 20);" i can put it in "Initialize" instead in Onbarupdate?

what changes? I have examples where 'indifferent where I put it .. gives me the same result

I understand if I put it in Initialize is executed only 1 time ..

In onbarupdate runs in each bar---then is more efficient algorithm in the first case

Is correct?

You were understanding this correctly (mostly). The Initialize() is run when the indicators window is opened, when an indicator instance is added to a chart and when you click OK on the indicator window. In other words it runs 3 times when you are adding an indicator.

OnBarUpdate is run at the close of each bar.

You had asked if it would be more efficient to set sma1 = SMA(Close, 20)[0] in Initialize() or OnBarUpdate.
This depends on what you are trying to do.

If you set this variable in Initialize() that would cause it to be run once only for the first bar and it would not keep updating. In other words its set once and done.
That being said, it would be more efficient to put it in OnStartUp() vs Initialize().

If you are wanting to set this value on every bar, then it will need to go in OnBarUpdate.

Below are a few links to the help guide:
Initialize() - http://www.ninjatrader.com/support/h...initialize.htm
OnStartUp() - http://www.ninjatrader.com/support/h.../onstartup.htm
OnBarUpdate() - http://www.ninjatrader.com/support/h...nbarupdate.htm

[turbofib]

thanks you all.... you always explain the concept in a comprehensive manner

[turbofib]

if I add an indicator whose parameters change at every bar .. need to put it in onbarupdate ..

Ex:
..
protected override void OnBarUpdate()
{
...
sma1 = SMA(Close/CurrentBar, 20);
..
}

Is correct?