Using eval with .getValue

[waynecd]

In order to use an array for several different moving averages I need to eval() a variable containing text with .getValue(0). However I get a null response when I debugPrintln().

How do I correct the following script to output the correct .getValue(0) and .getValue(-1).

Thank you.

var myStudy = null;
var vInit = false;
function main(){
if(vInit == false){
vCommonVar6 = ema( 34 , close(sym("ibm,5")));
vSymbol = getSymbol() + ","
vInit=true
}

var vCommonVar7 = vCommonVar6 + ".getValue(0)"
var vCommonVar8 = vCommonVar6 + ".getValue(-1)"
debugPrintln(eval(vCommonVar7));
debugPrintln(eval(vCommonVar8));
}

[eSignal_JasonK]

Hello Wayne,

The key is to make vCommonVar6 a string when declaring your vCommonVar7 and 8 variables. The entire expression needs to be a string. Surround the object name with quotes ( i.e. "vCommonVar6" ). Try the following.

var myStudy = null;
var vInit = false;
var vCommonVar6 = null;  // add to globals

function main(){
    if(vInit == false){
        vCommonVar6 = ema( 34 , close(sym("ibm,5"))); 
        vSymbol = getSymbol() + ","
        vInit=true
    }

    var vCommonVar7 = "vCommonVar6" + ".getValue(0)"
    var vCommonVar8 = "vCommonVar6" + ".getValue(-1)"
    debugPrintln("7: " + eval(vCommonVar7));
    debugPrintln("8: " + eval(vCommonVar8));
    
} 

[waynecd]

Thanks Jason,

It worked.

I still have a problem though. I would like the attached script to draw a table in a non-price pane but the last array does not seem to work or maybe the moving averages are not really defined. I'm not sure what is wrong.

If you have time I would appreciate your help.
The sample code is below, I also attached it as an efs.

Thank you.

Wayne

debugClear();
var vMAArray = new Array();
var myStudy = null;
var bInit = false;
var vSymbol = null;
var avgTR = null;
var highestC = null;
var lowestC = null;
var avgTR = null;
var iInterval1 = 1;
var iInterval2 = 5;
var iInterval3 = 15;
var iInterval4 = 60;
var iInterval5 = "D";
var iInterval6 = "W";
var iInterval7 = "M"; 
var iAvgType1 = null;
var iLength1 = null; 
var iAvgType2 = null;
var iLength2 = null; 
var iAvgType3 = null;
var iLength3 = null;
var iAvgType4 = null;
var iLength4 = null;
for (var i=1;i<=1;i++){
    for (var j=1;j<=4;j++){
        var vCommonVar = ("var xAvgr" + i + "c" + j +" = null");
        eval(vCommonVar);
    }
}
function main(){
    if(bInit==false){
        vSource = "close()";
        avgTR      = wma(21,atr(1));
        highestC   = upperDonchian(21,close());
        lowestC    = lowerDonchian(21,close());
        if(vSymbol == null) vSymbol = getSymbol().toUpperCase();
        //defines the symbol,interval to use in the next array to define the moving averages
        for (var i=1;i<=7;i++){
            var vCommonVar1 = "xSymbol" + i + " = vSymbol + \",\" + iInterval" + i;
            eval(vCommonVar1);
        }
        //defines the MOVING AVERAGE VARIABLES
        for (var i=1;i<=7;i++){
            var vCommonVar2 = "iInterval" + i;
                for (var j=1;j<=4;j++){
                    var vCommonVar3 = ("xAvgr" + i + "c" + j +
                                       " = offsetSeries(eval(iAvgType" + j + ")(iLength" + j + 
                                       ",eval(vSource)(sym(xSymbol" + i + "))),Offset)");
                //debugPrintln(vCommonVar3);
                vMAArray.push(eval(vCommonVar3));
//I CAN'T TELL IF THE MOVING AVERAGES WERE DEFINED AND STORED
//dfgh = vMAArray[i][1];                
//debugPrint(dfgh+"\n");
                }
        }
        bInit=true;
    } // bInit 
//HERE I WOULD LIKE TO USE THE DEFINED MOVING AVERAGE VARIABLES TO RUN THROUGH THE CODE
//BUT HOW DO I CREATE AN ARRAY TO RUN THROUGH AND RECOGNIZE THE DEFINED MOVING AVERAGES   
for (var k=1;k<=7;k++){
    var vCommonVar4 = "iInterval" + k;
    if(eval(vCommonVar4) != 0){
        var vCommonVar5 = "xAvgr" + k;
        if(k > 1){
            nX = inputXstart;
            nY -= nFontCY; ;
        }
        for (var l=1;l<=5;l++){
            var vCommonVar6 = "vCommonVar5" + "c" + l;
            var vCommonVar7 = "vCommonVar6" + ".getValue(0)"
            var vCommonVar8 = "vCommonVar6" + ".getValue(-1)"
//debugPrintln(eval(vCommonVar7));//does not output anything?????
           if(l < 5){
                var RowCol_Number = "Row" + k + "Col" + l
                if(eval(vCommonVar7) > eval(vCommonVar8)){
                    xFGColor = Color.black; 
                    xBGColor = Color.green; 
                    sStr     = "+" ;  
                }else if(eval(vCommonVar7) < eval(vCommonVar8)){
                    xFGColor = Color.black; 
                    xBGColor = Color.red; 
                    sStr     = "-" ;
                }else{
                    xFGColor = Color.black; 
                    xBGColor = Color.yellow; 
                    sStr     = "=" ; 
                }
                if(l = 1){
                    drawTextPixel(nX, nY, sStr, xFGColor, xBGColor,
                    Text.FRAME | Text.CENTER | Text.VCENTER | Text.BOLD,
                    null, nFontSize, RowCol_Number, nColWidth, nRowThickness);
                }else if(l > 1 &&  l < 5) {
                    drawTextPixel(nX+=nFontCX, nY, sStr, xFGColor, xBGColor,
                    Text.FRAME | Text.CENTER | Text.VCENTER | Text.BOLD,
                    null, nFontSize, RowCol_Number, nColWidth, nRowThickness);
                }                
            }else if(l == 5){
                sStr     = ""+ vCommonVar4 ;
                drawTextPixel(nX+=nFontCX, nY, sStr, Color.white, Color.black,
                Text.FRAME | Text.CENTER | Text.VCENTER | Text.BOLD,
                null, nFontSize, RowCol_Number, nColWidth, nRowThickness);
            }
        }
    }
}
    
//return vMAArray[1][1];
} 

[waynecd]

I had a typo in the first array but once corrected it still locks up in "Loading Data".

Here is the correction:

debugClear();
var vMAArray = new Array();
var myStudy = null;
var bInit = false;
var vSymbol = null;
var avgTR = null;
var highestC = null;
var lowestC = null;
var avgTR = null;
var iInterval1 = 1;
var iInterval2 = 5;
var iInterval3 = 15;
var iInterval4 = 60;
var iInterval5 = "D";
var iInterval6 = "W";
var iInterval7 = "M"; 
var iAvgType1 = null;
var iLength1 = null; 
var iAvgType2 = null;
var iLength2 = null; 
var iAvgType3 = null;
var iLength3 = null;
var iAvgType4 = null;
var iLength4 = null;
for (var i=1;i<=7;i++){
    for (var j=1;j<=4;j++){
        var vCommonVar = ("var xAvgr" + i + "c" + j +" = null");
        eval(vCommonVar);
    }
}
function preMain(){

}
function main(){
    if(bInit==false){
        vSource = "close()";
        avgTR      = wma(21,atr(1));
        highestC   = upperDonchian(21,close());
        lowestC    = lowerDonchian(21,close());
        if(vSymbol == null) vSymbol = getSymbol().toUpperCase();
        //defines the symbol,interval to use in the next array to define the moving averages
        for (var i=1;i<=7;i++){
            var vCommonVar1 = "xSymbol" + i + " = vSymbol + \",\" + iInterval" + i;
            eval(vCommonVar1);
        }
        //defines the MOVING AVERAGE VARIABLES
        for (var i=1;i<=7;i++){
            var vCommonVar2 = "iInterval" + i;
                for (var j=1;j<=4;j++){
                    var vCommonVar3 = ("xAvgr" + i + "c" + j +
                                       " = offsetSeries(eval(iAvgType" + j + ")(iLength" + j + 
                                       ",eval(vSource)(sym(xSymbol" + i + "))),Offset)");
                //debugPrintln(vCommonVar3);
                vMAArray.push(eval(vCommonVar3));
//I CAN'T TELL IF THE MOVING AVERAGES WERE DEFINED AND STORED
//dfgh = vMAArray[i][1];                
//debugPrint(dfgh+"\n");
                }
        }
        bInit=true;
    } // bInit 
//HERE I WOULD LIKE TO USE THE DEFINED MOVING AVERAGE VARIABLES TO RUN THROUGH THE CODE
//BUT HOW DO I CREATE AN ARRAY TO RUN THROUGH AND RECOGNIZE THE DEFINED MOVING AVERAGES   
for (var k=1;k<=7;k++){
    var vCommonVar4 = "iInterval" + k;
    if(eval(vCommonVar4) != 0){
        var vCommonVar5 = "xAvgr" + k;
        if(k > 1){
            nX = inputXstart;
            nY -= nFontCY; ;
        }
        for (var l=1;l<=5;l++){
            var vCommonVar6 = "vCommonVar5" + "c" + l;
            var vCommonVar7 = "vCommonVar6" + ".getValue(0)"
            var vCommonVar8 = "vCommonVar6" + ".getValue(-1)"
//debugPrintln(eval(vCommonVar7));//does not output anything?????
           if(l < 5){
                var RowCol_Number = "Row" + k + "Col" + l
                if(eval(vCommonVar7) > eval(vCommonVar8)){
                    xFGColor = Color.black; 
                    xBGColor = Color.green; 
                    sStr     = "+" ;  
                }else if(eval(vCommonVar7) < eval(vCommonVar8)){
                    xFGColor = Color.black; 
                    xBGColor = Color.red; 
                    sStr     = "-" ;
                }else{
                    xFGColor = Color.black; 
                    xBGColor = Color.yellow; 
                    sStr     = "=" ; 
                }
                if(l = 1){
                    drawTextPixel(nX, nY, sStr, xFGColor, xBGColor,
                    Text.FRAME | Text.CENTER | Text.VCENTER | Text.BOLD,
                    null, nFontSize, RowCol_Number, nColWidth, nRowThickness);
                }else if(l > 1 &&  l < 5) {
                    drawTextPixel(nX+=nFontCX, nY, sStr, xFGColor, xBGColor,
                    Text.FRAME | Text.CENTER | Text.VCENTER | Text.BOLD,
                    null, nFontSize, RowCol_Number, nColWidth, nRowThickness);
                }                
            }else if(l == 5){
                sStr     = ""+ vCommonVar4 ;
                drawTextPixel(nX+=nFontCX, nY, sStr, Color.white, Color.black,
                Text.FRAME | Text.CENTER | Text.VCENTER | Text.BOLD,
                null, nFontSize, RowCol_Number, nColWidth, nRowThickness);
            }
        }
    }
}
    
return xAvgr1c1;
} 

[eSignal_JasonK]

Hello Wayne,

The central problem is the string that you are building with this line of code.

var vCommonVar3 = ("xAvgr" + i + "c" + j +
                " = offsetSeries(eval(iAvgType" + j + ")(iLength" + j + 
                ",eval(vSource)(sym(xSymbol" + i + "))),Offset)"); 

The resulting string has embedded eval() calls in it. That in itself is not illegal, but I think it is adding a layer of complexity for you. The syntax of the resulting string is invalid for two reasons. You can see the values of your strings by adding a debugPrintln(vCommonVar3) on the following line.



First, you have references to three variable that are not yet defined, iAvgType#, iLength# and Offset. Secondly, the vSource variable is defined as "close()," which causes the syntax problem. The string, "close()," is getting concatenated to the front of your "sym(.." string, which results in "close()sym(..." Remove the () function call parameters from your variable declaration (i.e. var vSource = "close" ; ) and embed them in their appropriate places when building your string.

What I would do instead of including the eval() statements as text in this string is to execute these evals while building this string. That way, the values of those variables get embedded properly into the string, which will be evaluated by your eval() statement in the Array.push(). Doing it this way helps when debugging because you can pass the string to debugPrintln() and visually check the syntax to make sure everything is good to go from that point.

Here's an example of what it should look like. Please note that this will generate an error in your formula because of the undefined variable references. However, once you get those defined, it should work.

                var vCommonVar3 = ("xAvgr" + i + "c" + j +
                                   " = offsetSeries(" + eval("iAvgType" + j) + "(" + eval("iLength" + j) + 
                                   "," + vSource + "((sym(" + eval("xSymbol" + i) + "))))," + Offset + ");"); 

[waynecd]

Everything works fine now.

Thanks again.

[eSignal_JasonK]

Wayne, you're most welcome. Thanks for the update.