Limit plot to X number of bars back

[waynecd]

Hi,

The enclosed efs uses the DrawTextCtr variable to control the number of bars back used to plot the DrawTextRelative(...). This reduces overhead resources.
It draws small colored squares at the bottom of the chart. I found this method via a forum search.

Problem: Initially it plots as intended (LookBack of 300 bars back) but it soon starts to erase the plotted squares from left to right until only one square remains.

I would like it to keep the last 300 squares so that as a new square is plotted, the square at the begining is erased (now 301 bars back).
I'm sure it's a simple solution but it escapes me.

Thanks in advance.

Wayne

debugClear();
var bInit = false; 
var aFPArray = new Array(); 

function preMain() {
    setPriceStudy(true);
var x=0; 
    aFPArray[x] = new FunctionParameter( "Interval0", FunctionParameter.STRING); 
    with( aFPArray[x++] ) { 
        setName( "Price Interval" ); 
        setDefault(  ); 
    }   
}
var myStudy0 = null; 
var myStudy1 = null; 
var DrawTextCntr = 0;
var LookBack = 300;

function main(Interval0) { 

    var myVar0,myVar1; 
    var TempColor = Color.white;


    if ( bInit == false ) { 
        setDefaultBarFgColor(Color.blue, 0);
        setDefaultBarFgColor(Color.red, 1);
        if(Interval0 == null) Interval0 = getInterval();
        if(myStudy0 == null) myStudy0 = sma( 9, inv(Interval0) ); 
        myStudy0 = getSeries(myStudy0); 
        if(myStudy1 == null) myStudy1 = sma( 13, inv(Interval0) ); 
        myStudy1 = getSeries(myStudy1); 
        bInit = true; 
    }
    var Close0 = close(0);
    var myVar0 = myStudy0.getValue(0); 
    var myVar1 = myStudy1.getValue(0); 

    if(Close0 > myVar0 && myVar0 > myVar1) TempColor = Color.green;//Price is above MA0 & MA0 is above MA1
    if(Close0 > myVar0 && myVar0 < myVar1) TempColor = Color.red;//Price is above MA0 & MA0 is below MA1
    if(Close0 < myVar0 && myVar0 < myVar1) TempColor = Color.RGB(218,218,165);//Price is below MA1 & MA0 is below MA1
    if(Close0 < myVar0 && myVar0 > myVar1) TempColor = Color.RGB(255,230,195);//Price is below MA1 & MA0 is above MA1

    drawTextRelative(0,1,"n",TempColor,null,Text.VCENTER | Text.RELATIVETOBOTTOM |Text.CENTER|Text.BOLD,"Wingdings",10,"n0"+ DrawTextCntr++);
    if (DrawTextCntr > LookBack) DrawTextCntr = 0;

   return new Array( myStudy0, myStudy1 ); 
} 

[ACM]

Re: Limit plot to X number of bars back

waynecd
You are incrementing drawTextCntr on every tick whereas you should do it only once per bar
Alex

Originally posted by waynecd
Hi,

The enclosed efs uses the DrawTextCtr variable to control the number of bars back used to plot the DrawTextRelative(...). This reduces overhead resources.
It draws small colored squares at the bottom of the chart. I found this method via a forum search.

Problem: Initially it plots as intended (LookBack of 300 bars back) but it soon starts to erase the plotted squares from left to right until only one square remains.

I would like it to keep the last 300 squares so that as a new square is plotted, the square at the begining is erased (now 301 bars back).
I'm sure it's a simple solution but it escapes me.

Thanks in advance.

Wayne

debugClear();
var bInit = false; 
var aFPArray = new Array(); 

function preMain() {
    setPriceStudy(true);
var x=0; 
    aFPArray[x] = new FunctionParameter( "Interval0", FunctionParameter.STRING); 
    with( aFPArray[x++] ) { 
        setName( "Price Interval" ); 
        setDefault(  ); 
    }   
}
var myStudy0 = null; 
var myStudy1 = null; 
var DrawTextCntr = 0;
var LookBack = 300;

function main(Interval0) { 

    var myVar0,myVar1; 
    var TempColor = Color.white;


    if ( bInit == false ) { 
        setDefaultBarFgColor(Color.blue, 0);
        setDefaultBarFgColor(Color.red, 1);
        if(Interval0 == null) Interval0 = getInterval();
        if(myStudy0 == null) myStudy0 = sma( 9, inv(Interval0) ); 
        myStudy0 = getSeries(myStudy0); 
        if(myStudy1 == null) myStudy1 = sma( 13, inv(Interval0) ); 
        myStudy1 = getSeries(myStudy1); 
        bInit = true; 
    }
    var Close0 = close(0);
    var myVar0 = myStudy0.getValue(0); 
    var myVar1 = myStudy1.getValue(0); 

    if(Close0 > myVar0 && myVar0 > myVar1) TempColor = Color.green;//Price is above MA0 & MA0 is above MA1
    if(Close0 > myVar0 && myVar0 < myVar1) TempColor = Color.red;//Price is above MA0 & MA0 is below MA1
    if(Close0 < myVar0 && myVar0 < myVar1) TempColor = Color.RGB(218,218,165);//Price is below MA1 & MA0 is below MA1
    if(Close0 < myVar0 && myVar0 > myVar1) TempColor = Color.RGB(255,230,195);//Price is below MA1 & MA0 is above MA1

    drawTextRelative(0,1,"n",TempColor,null,Text.VCENTER | Text.RELATIVETOBOTTOM |Text.CENTER|Text.BOLD,"Wingdings",10,"n0"+ DrawTextCntr++);
    if (DrawTextCntr > LookBack) DrawTextCntr = 0;

   return new Array( myStudy0, myStudy1 ); 
} 

[waynecd]

Alex,

Thanks.

I changed line 59 right above the return statement to:

    if(getBarState() == BARSTATE_NEWBAR) if (DrawTextCntr > LookBack) DrawTextCntr = 0; 

But it still does it.

Is that what you meant?

Wayne

[ACM]

waynecd
That is not what I said.
You are incrementing the DrawTextCntr variable inside the drawTextRelative() command which is executed on every tick.
You need to instead increment it inside a conditional statement that checks for BARSTATE_NEWBAR (same as the one you show in your example). Then inside the drawTextRelative() command you just use the DrawTextCntr variable
Inside that same BARSTATE_NEWBAR conditional statement you can then also have the lines of code shown in your example since they only need to be evaluated/executed once per bar
Alex

Originally posted by waynecd
Alex,

Thanks.

I changed line 59 right above the return statement to:

    if(getBarState() == BARSTATE_NEWBAR) if (DrawTextCntr > LookBack) DrawTextCntr = 0; 

But it still does it.

Is that what you meant?

Wayne

[waynecd]

Alex,

That worked perfectly. From your last explanation I see how computing on every tick can affect some of my other scripts.

I really appreciate the explanation.

Wayne

[ACM]

Wayne
You are welcome
Alex

Originally posted by waynecd
Alex,

That worked perfectly. From your last explanation I see how computing on every tick can affect some of my other scripts.

I really appreciate the explanation.

Wayne