AFL for multiple Bollinger Bands

AFL Programming
1

A follower asked about plotting multiple sets of Bollinger Bands in AFL. I had a little spare time this morning, so here you go:

// AFL to plot three sets of Bollinger Bands®
// By John Bollinger
// https://www.BollingerBands.com
// Copyright Bolinger Capital Management 2018
//
// Data to use, deafault to close
P = ParamField("Price field", -1 );
// User BB period selection
Periods1 = Param("Periods 1", 10, 2, 100, 1 );
Periods2 = Param("Periods 2", 20, 2, 100, 1 );
Periods3 = Param("Periods 3", 50, 2, 100, 1 );
// User BB width selection
Width1 = Param("Width 1", 2, 0, 10, 0.05 );
Width2 = Param("Width 2", 2, 0, 10, 0.05 );
Width3 = Param("Width 3", 2, 0, 10, 0.05 );
// User BB color selection
ColorUpper = ParamColor("Color 1", colorRed );
ColorMiddle = ParamColor("Color 2", colorBlue );
ColorLower = ParamColor("Color 3", colorGreen );
// User BB line selection
Style1 = ParamStyle("Style 1", styleDots );
Style2 = ParamStyle("Style 2", styleLine );
Style3 = ParamStyle("Style 3", styleDashed );
// Plot the first set of bands
Plot( BBandTop( P, Periods1, Width1 ), "upperBB1", ColorUpper, Style1 );
Plot( MA(P, Periods1), "middleBB1", ColorMiddle, Style1 );
Plot( BBandBot( P, Periods1, Width1 ), "lowerBB1", ColorLower, Style1 );
// Plot the second set of bands
Plot( BBandTop( P, Periods2, Width2 ), "upperBB2", ColorUpper, Style2 );
Plot( MA(P, Periods2), "middleBB2", ColorMiddle, Style2 );
Plot( BBandBot( P, Periods2, Width2 ), "lowerBB2", ColorLower, Style2 );
// Plot the third set of bands
Plot( BBandTop( P, Periods3, Width3 ), "upperBB3", ColorUpper, Style3 );
Plot( MA(P, Periods3), "middleBB3", ColorMiddle, Style3 );
Plot( BBandBot( P, Periods3, Width3 ), "lowerBB3", ColorLower, Style3 );
// That's all folks!

Enjoy,

John

bb3

11 Likes
2

Thank you John for your contribution

2 Likes
3

And here is way more simplified version doing same thing.

/// AFL to plot three sets of Bollinger Bands®
/// By fxshrat@gmail.com
/// @link https://forum.amibroker.com/t/afl-for-multiple-bollinger-bands/8225/3

SetChartOptions( 0, chartShowDates | chartShowArrows | chartWrapTitle );

P = ParamField("Price field", -1 );

// default periods and styles
per1 = 10;	st1 = styleDots;
per2 = 20;	st2 = styleLine;
per3 = 50;	st3 = styleDashed;

for ( i = 1; i <= 3; i++ ) {
	// Set Param BB periods
	VarSet( "Periods" + i, Param("Periods " + i, VarGet("per" + i), 2, 100, 1 ));
	// Set Param BB width 
	VarSet( "Width" + i, Param("Width " + i, 2, 0, 10, 0.05 ) );
	// Set Param BB line style
	VarSet( "Style" + i, ParamStyle("Style " + i, VarGet("st" + i) ));
}

for ( i = 1; i <= 3; i++ ) {
	// Plot the set of bands
	vg_period = VarGet("Periods" + i);
	vg_style = VarGet("Style" + i);
	vg_width = VarGet("Width" + i);
	Plot( BBandTop( P, vg_period, vg_width), "upperBB" +i, ParamColor("Color 1", colorRed ), vg_style );
	Plot( MA(P, vg_period), "middleBB" + i, ParamColor("Color 2", colorBlue ), vg_style );
	Plot( BBandBot( P, vg_period, vg_width ), "lowerBB" +i, ParamColor("Color 3", colorGreen ), vg_style );
}
7 Likes
4

It is a privilege for us - AmiBroker users, that such Hall of Famer - Mr. John Bollinger has joined our forum today. Thank you for creating Bollinger Bands :slight_smile:

4 Likes
5

Oh, I didn't know about VarSet(). Nice. Thanks.

 John
1 Like
6

It is entirely my pleasure to have a seat at the table.

Thank you,

  John
5 Likes
7

I watched you every trading day in the 80's on FNN.
-S

8

While we are at making code shorter/simpler, my 2 cents' worth - we can get away without VarGet/VarSet as Params can be placed inside just one loop.

// AFL to plot three sets of Bollinger Bands®
// By John Bollinger
// https://www.BollingerBands.com
// Copyright Bolinger Capital Management 2018
//
// Data to use, default to close
// 
// Simplified by TJ
Version( 6.10 );

P = ParamField("Price field", -1 );

def_styles = MxFromString("{{8,1,32}}"); // dots, line, dashes

for ( i = 1; i <= 3; i++ ) 
{
	// Plot the set of bands
	period = Param("Periods " + i, 10 * i, 2, 100, 1 );
	width = Param("Width " + i, 2, 0, 10, 0.05 );
	style = ParamStyle("Style " + i, def_styles[ 0 ][ i - 1 ] );
	Plot( BBandTop( P, period, width), "upperBB" +i, ParamColor("Color Up", colorRed ), style );
	Plot( MA(P, period), "middleBB" + i, ParamColor("Color Mid", colorBlue ), style );
	Plot( BBandBot( P, period, width ), "lowerBB" +i, ParamColor("Color Lo", colorGreen ), style );
}
15 Likes
9

While we are at VarSet/VarGet,
The reason for why those have been used instead is simple...
Being able to still pick a single variable (previously set in loop) outside of loop.

Example: Including BB band variable to Buy/Sell rules and plotting Shapes.

Originally I had set periods + width via VarSet. But it is rather over complication so I thought it is better to just set Bands and MA all at once.

The idea of using MxFromString for default periods actually is a good one and have added it to code below with reference to original idea provider.

/// AFL to plot three BB Bands + (basic example) Signals + Shapes
/// By fxshrat@gmail.com
/// @link https://forum.amibroker.com/t/afl-for-multiple-bollinger-bands/8225/9
/// Suggestion of using Matrix for default periods by T. Janeczko
/// https://forum.amibroker.com/t/afl-for-multiple-bollinger-bands/8225/8
SetChartOptions( 0, chartShowDates | chartShowArrows | chartWrapTitle );
Plot( C, "Price", colorDefault, styleBar );

// price field
P = ParamField("Price field", -1 );
// default periods and styles (suggestion of using MxFromString by AB developer)
default_per = MxFromString( "[10;20;50]" );// default periods
default_style = MxFromString( "[8;1;32]" );// dots, line, dashes

for ( i = 1; i <= 3; i++ ) {
	// Set Param BB periods & width
	per = Param("Periods " + i, default_per[i-1][0], 2, 100, 1 );
	width = Param("Width " + i, 2, 0, 10, 0.05 );
	//Set Bands
	VarSet( "BBandTop" + i, BBandTop( P, per, width));
	VarSet( "MA" + i, MA( P, per));
	VarSet( "BBandBot" + i, BBandBot( P, per, width));
	// Set Param BB line style
	VarSet( "Style" + i, ParamStyle("Style " + i, default_style[i-1][0] ));
}

for ( i = 1; i <= 3; i++ ) {
	// Plot the set of bands
	vg_style = VarGet("Style" + i);
	Plot( VarGet( "BBandTop" + i), "upperBB" +i, ParamColor("Color BBandTop", colorRed ), vg_style );
	Plot( VarGet( "MA" + i), "middleBB" + i, ParamColor("Color MA", colorBlue ), vg_style );
	Plot( VarGet( "BBandBot" + i), "lowerBB" +i, ParamColor("Color BBandBot", colorGreen ), vg_style );
}

// Some basic signal example + plot of shapes
Buy = Cross(C, BBandTop1) AND BBandTop1 > Ref(HHV(BBandTop1, 20),-1);
Sell = Cross(C, BBandTop3) AND BBandTop3 > Ref(HHV(BBandTop3, 20),-1);

Buy = ExRem( Buy, Sell );
Sell = ExRem( Sell, Buy );

PlotShapes( Buy * shapeUpArrow + Sell * shapeDownArrow,
            IIf( Buy, colorGreen, colorOrange ), layer = 0,
            y = IIf( Buy, L, H ), -12 );

435

7 Likes
10

That was a great time. I miss those days a lot!

Best,

 John
11

Hi is it possible to put foreign "Ticker" BB band under the other ticker
can you tell me the code for that afl

12

@Sam1, as you appear to be "new" to the forum, you should spend some time searching.

As you search, you will find that the posts that get the most/best help are ones that show the original poster's work, and where they are having difficulty.

If you are also very new to AmiBroker/AFL, then you will have to spend lots of time learning.

But in Answer to your question... Is if possible - YES. Can I tell you the code - YES. Am I going to tell/give you the code - NO.

While you might find that rude or disrespectful, I seriously doubt that you will only use AB for this one idea. Because of that, I am going to make you put an effort in to work with and learn some AFL.

As I am sure you will have some issues/difficulties, here is a great link - for debugging your code: How do I debug my formula?

Good luck in your new journey. Come back and post your work/code and then you will tend to receive much more pointed help on your issues.

4 Likes