Code structure + a couple more questions

[thestranger]

Hi,

I have performed a quick search on here and the KnowledgeBase for a guide/pointers on the "correct" way to structure/indent code. Unfortunately with no luck. Does anyone have any suggestions?

Also in the following code;

1) Will nTradeEntryPrice obtain the purchase price of my trade?
2) And I want to use the atr value, (var atrLevel) at the point when the purchase is made, as the basis of my stop loss point. Is this calculated in the correct section of the code?

Thanks for any help in advance.
-----------------------------------------------------------------------------------

var vDonch = null;
var vDonch2 = null;
var nSignal;
var nTradeEntryPrice;
var nStopLevel;
var atrLevel;
var inTrade;
var nNewTrade;

function preMain() {

    setPriceStudy(true);
    setStudyTitle("Donchian");
    setCursorLabelName("20 Day High", 0);
    setCursorLabelName("20 Day Low", 1);
    setCursorLabelName("10 day High Exit", 2);
    setCursorLabelName("10 day Low Exit", 3);
    setColorPriceBars(true);
    setDefaultBarFgColor (Color. blue, 0);
    setDefaultBarFgColor (Color. red, 1);
    setDefaultBarFgColor (Color. green, 2);
    setDefaultBarFgColor (Color. green, 3);
    setDefaultBarThickness(1, 0);
    setDefaultBarThickness(1, 1);
    setDefaultBarThickness(1, 2);
    setDefaultBarThickness(1, 3);
    setDefaultPriceBarColor(Color.black);

}

function main() {

    if (vDonch == null) vDonch = new DonchianStudy (20,0);
    if (vDonch2 == null) vDonch2 = new DonchianStudy (10,0);
    

// identify entry price

if (nNewTrade == 1) {
    nTradeEntryPrice = open();
    nNewTrade = 0;
    atrLevel = atr(20);
    inTrade = 1;

    if (Strategy.isLong() == true) setPriceBarColor(Color.green);
    if (Strategy.isShort() == true) setPriceBarColor(Color.red);

}

// stop loss/profit exit

if (inTrade == 1 && nSignal > 0) {
    if (low() <= (nTradeEntryPrice - nStopLevel)) {

    Strategy.doSell("Stop Sell", Strategy.LIMIT, Strategy.THISBAR, Strategy.ALL, nStopLevel);

    inTrade = 0; 
    }
}

else if (low() <= vDonch2.getValue(DonchianStudy.LOWER, -1)) { 
    var longExit = vDonch2.getValue(DonchianStudy.LOWER, -1);
    if (open() < longExit) longExit = open(); {

    Strategy.doSell("10 day low",Strategy.LIMIT,Strategy.THISBAR,Strategy.ALL,longExit);

    inTrade = 0;  
    }
}

if (inTrade == 1 && nSignal < 0) {
    if (high() >= (nTradeEntryPrice + nStopLevel)) {

    Strategy.doCover("Cover",Strategy.LIMIT, Strategy,THISBAR,Strategy.ALL,nStopLevel);

    inTrade = 0;
    }
}

else if (high() >= vDonch2.getValue(DonchianStudy.UPPER, -1)) {
    var shortExit = vDonch2.getValue(DonchianStudy.UPPER, -1);
    if (open() > shortExit) shortExit = open(); {

Strategy.doSell("10 day low",Strategy.LIMIT,Strategy.THISBAR,Strategy.ALL,shortExit);

    inTrade = 0;
    }
}

//identify entry signal

if (inTrade == 0) {
if (high() >= vDonch.getValue(DonchianStudy.UPPER, -1)) {
    nSignal = 1;
    nNewTrade = 1;
    }
}

if (inTrade == 0) {
if (low() <= vDonch.getValue(DonchianStudy.LOWER, -1)) {
    nSignal = -1;
    nNewTrade = 1;
    }
}

//execute trade

if  ((nNewTrade == 1) && (nSignal > 0)) {

    Strategy.doLong("Long", Strategy.MARKET, Strategy.NEXTBAR);
    nStopLevel = nTradeEntryPrice -  (atrLevel * 2);
    
}

if  ((nNewTrade == 1) && (nSignal < 0)) {

    Strategy.doShort("Short", Strategy.MARKET, Strategy.NEXTBAR);
    nStopLevel = nTradeEntryPrice +  (atrLevel * 2);
    
}

return new Array 

(vDonch.getValue (DonchianStudy.UPPER),
vDonch.getValue (DonchianStudy.LOWER),
vDonch2.getValue (DonchianStudy.UPPER),
vDonch2.getValue (DonchianStudy.LOWER));

} 

[Guest]

theStranger,

Here are two links regarding some standards used in writing code ...


CamelCase - http://en.wikipedia.org/wiki/Intercap

Programming Style - http://en.wikipedia.org/wiki/Coding_standard

[eSignal_JasonK]

Re: Code structure + a couple more questions

Hello thestranger,

Originally posted by thestranger
Hi,

I have performed a quick search on here and the KnowledgeBase for a guide/pointers on the "correct" way to structure/indent code. Unfortunately with no luck. Does anyone have any suggestions?

Also in the following code;

1) Will nTradeEntryPrice obtain the purchase price of my trade?
2) And I want to use the atr value, (var atrLevel) at the point when the purchase is made, as the basis of my stop loss point. Is this calculated in the correct section of the code?

Thanks for any help in advance.
-----------------------------------------------------------------------------------

1) Yes, because your entry calls are using MARKET/NEXTBAR constants. Keep in mind this is only during the back test.
2) The location where you're setting the value of atrLevel is incorrect. What is happening is that the atrLevel will be using the value of the atr at the close of the bar following the previous trade signal. You should move the assignment for atrLevel to the top of main outside of any conditional statements. Also, using the following would be the proper way to get the value you need from the atr series.

atrLevel = atr(20, 0);

[thestranger]

Thanks a lot for the links stevehare2003. Hopefully i can improve my structuring.

And thanks once again JasonK. Just one more question on my code. In relation to the atr(20, 0) series. Should i declare atrLevel as null in the global variables and then put if (atrLevel == null) atrLevel = atr(20, 0) in the first part of the main; Or is this not necessary?

I'm thinking the same for the donchian study. Is this null statement necessary? Or can i simply put vDonch = new DonchianStudy (20, 0);

Thanks

[eSignal_JasonK]

Hello thestranger,

Originally posted by thestranger
Thanks a lot for the links stevehare2003. Hopefully i can improve my structuring.

And thanks once again JasonK. Just one more question on my code. In relation to the atr(20, 0) series. Should i declare atrLevel as null in the global variables and then put if (atrLevel == null) atrLevel = atr(20, 0) in the first part of the main; Or is this not necessary?

No. Remember this rule of thumb when working with the EFS2 built-in studies. If you specify a bar index in the parameter list, the return result will be a single value. If you do not ask for a specific bar index, a Series Object of the study will be created and assigned to your variable, or container.

var atrLevel = atr(20, 0); // This retrieves one value

var xAtr = atr(20); // Creates a Series Object of the atr() study.

As it pertains to your specific formula, you do not have any need for using the Series of the atr, so just retrieve the specific bar's value that you need. It would not make much difference if atrLevel were global or local. Local will work just fine.

If you were to do this:

var atrLevel = null;

function main() {
    if (atrLevel == null) atrLevel = atr(20, 0);
    ....
} 

atrLevel would be set to the first (oldest) bar's value of the atr() study and would never change. If you wanted to work with the Series Object of the atr() study, this is how you would do it.

var xAtr = null;  // This will contain a Series Object.

function main() {
    if (xAtr == null) xAtr = atr(20);  // this happens only once.

    var atrLevel = xAtr.getValue(0);  // retrieve the current value of the xAtr study.
    ....
} 

The above accomplishes the same thing as just asking for the bar index of the atr() study. It's just a little more code.

I'm thinking the same for the donchian study. Is this null statement necessary? Or can i simply put vDonch = new DonchianStudy (20, 0);

Thanks

You're on the right track, however, you're using the EFS1 Donchian study object, which does not create a Series Object. You should use the following.

function main() {
    var nDonch_Upper  = upperDonchian(20, 0);  // current value
    var nDonch_Upper2 = upperDonchian(10, 0);  // current value
    var nDonch_Lower  = lowerDonchian(20, 0);  // current value
    var nDonch_Lower2 = lowerDonchian(10, 0);  // current value

    // use the above variables in your conditional statements

    ....

    return new Array(nDonch_Upper, nDonch_Lower, nDonch_Upper2, nDonch_Lower2);
} 

[thestranger]

JasonK you have been a great help again. I think i'm slowly picking things up. I didnt pick up the differences between EFS1 & EFS2.

[thestranger]

I spoke too soon

I have made the changes you suggested. However i now get an error "nDonch_Lower2 has no properties". I tried to dissect the code to just use the entry section, still no luck. It seems to me that the donchian values are not being delivered. After having a quick search on the forum i noticed a similar thread. I therefore tried to insert a line of code directly after this part;

var nDonch_Upper = upperDonchian (20, 0);
var nDonch_Upper2 = upperDonchian (10, 0);
var nDonch_Lower = lowerDonchian (20, 0);
var nDonch_Lower2 = lowerDonchian (10, 0);

if(nDonch_Upper || nDonch_Upper2 || nDonch_Lower || nDonch_Lower2 == null) return;

Although it removed the error in the syntax check my chart is blank and no entries are triggered. I tried a few variations of the above but without success.

Any ideas?

var nSignal;
var nTradeEntryPrice;
var nStopLevel;
var atrLevel = null;
var inTrade;
var nNewTrade;

function preMain() {

    setPriceStudy(true);
    setStudyTitle("Donchian");
    setCursorLabelName("20 Day High", 0);
    setCursorLabelName("10 Day High", 1);
    setCursorLabelName("20 day Low", 2);
    setCursorLabelName("10 day Low", 3);
    setColorPriceBars(true);
    setDefaultBarFgColor (Color.blue, 0);
    setDefaultBarFgColor (Color.red, 1);
    setDefaultBarFgColor (Color.green, 2);
    setDefaultBarFgColor (Color.green, 3);
    setDefaultBarThickness(1, 0);
    setDefaultBarThickness(1, 1);
    setDefaultBarThickness(1, 2);
    setDefaultBarThickness(1, 3);
    setDefaultPriceBarColor(Color.black);

}

function main() {

    var nDonch_Upper = upperDonchian (20, 0);
    var nDonch_Upper2 = upperDonchian (10, 0);
    var nDonch_Lower  = lowerDonchian (20, 0);
    var nDonch_Lower2 = lowerDonchian (10, 0);
    if (atrLevel == null) atrLevel = atr(20, 0);
    

// identify entry price

if (nNewTrade == 1) {
    nTradeEntryPrice = open();
    nNewTrade = 0;
    inTrade = 1;

}

// stop loss/profit exit

if (inTrade == 1 && nSignal > 0) {
    if (low() <= (nTradeEntryPrice - nStopLevel)) {

    Strategy.doSell("Stop Sell", Strategy.LIMIT, Strategy.THISBAR, Strategy.ALL,nStopLevel);

    inTrade = 0; 
    }
}

else if (low() <= nDonch_Lower2.getValue(-1)) { 
    var longExit = nDonch_Lower2.getValue(-1);
    if (open() < longExit) longExit = open(); {

    Strategy.doSell("10 day low",Strategy.LIMIT,Strategy.THISBAR,Strategy.ALL,longExit);

    inTrade = 0;  
    }
}

if (inTrade == 1 && nSignal < 0) {
    if (high() >= (nTradeEntryPrice + nStopLevel)) {

    Strategy.doCover("Cover",Strategy.LIMIT, Strategy.THISBAR,Strategy.ALL,nStopLevel);

    inTrade = 0;
    }
}

else if (high() >= nDonch_Upper2.getValue(-1)) {
    var shortExit = nDonch_Upper2.getValue(-1);
    if (open() > shortExit) shortExit = open(); {

Strategy.doSell("10 day low",Strategy.LIMIT,Strategy.THISBAR,Strategy.ALL,shortExit);

    inTrade = 0;
    }
}

//identify entry signal

if (inTrade == 0) {
if (high() >= nDonch_Upper, -1) {
    nSignal = 1;
    nNewTrade = 1;
    }
}

if (inTrade == 0) {
if (low() <= nDonch_Lower, -1) {
    nSignal = -1;
    nNewTrade = 1;
    }
}

//execute trade

if  ((nNewTrade == 1) && (nSignal > 0)) {

    Strategy.doLong("Long", Strategy.MARKET, Strategy.NEXTBAR);
    setPriceBarColor(Color.green);
    nStopLevel = nTradeEntryPrice -  (atrLevel * 2);
    
}

if  ((nNewTrade == 1) && (nSignal < 0)) {

    Strategy.doShort("Short", Strategy.MARKET, Strategy.NEXTBAR);
    setPriceBarColor(Color.red);
    nStopLevel = nTradeEntryPrice +  (atrLevel * 2);
    
}

return new Array (nDonch_Upper, nDonch_Lower, nDonch_Upper2, nDonch_Lower2);

} 

[ACM]

thestranger
There are several errors in the script. For example the following
var nDonch_Upper = upperDonchian (20, 0);
var nDonch_Upper2 = upperDonchian (10, 0);
var nDonch_Lower = lowerDonchian (20, 0);
var nDonch_Lower2 = lowerDonchian (10, 0);
are all values and not series objects hence you cannot later in the script use nDonch_Upper2.getValue(-1) or nDonch_Lower2.getValue(-1) in your conditions.
As Jason explained in his reply in order to be able to use the getValue() method you must have declared the series object first. So either you declare nDonch_Upper, nDonch_Upper2, etc as series ie
var nDonch_Upper = upperDonchian (20);
var nDonch_Upper2 = upperDonchian (10);
var nDonch_Lower = lowerDonchian (20);
var nDonch_Lower2 = lowerDonchian (10);
in which case you can then use the getValue() method to retrieve the values from the series (as you are currently doing in your script) or you retrieve the value of the study directly inside the conditions by using the barIndex parameter ie upperDonchian(20,-1). For example
else if (high() >= upperDonchian(20,-1)) {
Also later in the script you have a couple of conditions that are incorrect for example if (high() >= nDonch_Upper, -1). Depending on the solution you decide to implement you will need to correct these conditions with the appropriate syntax.
Alex

[thestranger]

Admittedly that was a daft mistake! Thanks for your help.