extend line to the left

arnie · Postby **arnie** » 20 May 2015

I'm having an issue here regarding extending a line to the left.
What am I missing? I'd like the line to extend to the first bar of the chart or at least 3 or 4 days ago, not only half of yesterday's.

Code: Select all

inputs:

	Color					(white),

	RightShift				(50),

	ExtendLeft				(true),

	ExtendRight				(true);

	

variables:

	firstBar				(0),

	intrabarpersist	lastPrice	(0);



if currentbar = 1 then 

	firstBar = currentbar;



lastPrice = close;



if ExtendLeft = true then begin

	for value1 = 0 to (currentbar - firstBar) begin

		plot1[value1](lastPrice,"lastPrice", Color);

	end;

end;



if ExtendRight = true then begin

	for value1 = 0 to RightShift begin

		Plot1[-value1](lastPrice, "lastPrice", Color);

	end;

end;



noplot(1);

JoshM · Postby **JoshM** » 20 May 2015

I'm having an issue here regarding extending a line to the left.
What am I missing? I'd like the line to extend to the first bar of the chart or at least 3 or 4 days ago, not only half of yesterday's.

It's due to MaxBarsBack of the indicator. When I change the following of your code:

Code: Select all


if (LastBarOnChart_s) then begin 



	if (ExtendLeft = true) then begin



		Print("length: ", Symbol_Length, ", maxbarsback: ", MaxBarsBack);



		for value1 = 0 to Symbol_Length - MaxBarsBack begin

		

	      plot1[value1](lastPrice, "lastPrice", Color);

	      

	   end;

	   

	end;



end;

I get the following output:

length: 173.00 maxbarsback: 0.00
length: 173.00 maxbarsback: 6.00
length: 173.00 maxbarsback: 12.00
length: 173.00 maxbarsback: 21.00
length: 173.00 maxbarsback: 35.00
length: 173.00 maxbarsback: 58.00
length: 173.00 maxbarsback: 95.00

So MaxBarsBack automatically increments when set to Auto-detect (as it should). What I find odd, however, is that setting the MaxBarsBack setting explicitly to a low value (like 10), I get this output:

length: 174.00, maxbarsback: 10.00
length: 174.00, maxbarsback: 17.00
length: 174.00, maxbarsback: 29.00
length: 174.00, maxbarsback: 48.00
length: 174.00, maxbarsback: 79.00
length: 174.00, maxbarsback: 129.00
length: 174.00, maxbarsback: 129.00
length: 174.00, maxbarsback: 129.00
length: 174.00, maxbarsback: 129.00

That's odd because the script starts calculating with a MaxBarsBack of 10 (like I specified), but then automatically increments it exactly as specified in the documentation.

In this situation, I'd expect the script to throw the "Tried to reference back more bars. Please increase the Max Bars Back setting" error message, and not to override the manual setting.

(Although I might misunderstand how MaxBarsBack set to 'User Specified' should work).

JoshM · Postby **JoshM** » 20 May 2015

Of course, we can always use a trend line to draw a line to the beginning of the chart, although that still requires a little gap for the `MaxBarsBack` value. I, at least, couldn't draw/update a trend line to the very first bar on the chart.

Code: Select all


Inputs:

   Color(red),

   RightShift(50),

   ExtendLeft(true),

   ExtendRight(true);

   

Variables:

   intrabarpersist lastPrice(0),

   pastLine(0), futureLine(0), barsBack(0);

   

if (CurrentBar = 2) then begin



	pastLine = TL_New_s(Date[1], Time_s[1], Close[1],

		Date, Time_s, Close);



	TL_SetColor(pastLine, Color);

	

end;



lastPrice = close;



if (LastBarOnChart_s) then begin 



	barsBack = Symbol_Length - MaxBarsBack;



	if (ExtendLeft = true) then begin



		TL_SetEnd_s(pastLine, Date, 

			Time_s, lastPrice);

		

		TL_SetBegin_s(pastLine, Symbol_Date[barsBack], 

			Symbol_Time_s[barsBack], lastPrice);

			   

	end;



end;

arnie · Postby **arnie** » 20 May 2015

Of course, we can always use a trend line to draw a line to the beginning of the chart,

The problem with the trendline is that annoying lag that exist between last price and when the trendline actualy move to the last price.
A line does not show that lag which is more suited for the purpose of this study.

extend line to the left

extend line to the left

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Re: extend line to the left

Re: extend line to the left