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hello stephane,
Lastvalue() works on the last value of the Barindex() while Barcount changes
with QuickAFL.
Also, in general I try to stay away from using array functions inside loops.
I think this is also better from the performance viewpoint. In your example
it may be better to define an array RSI14 = RSI(14) and then inside the loop
access the last value with RSI14[barcount-1]. I copy below some comments
from TJ on this topic.
best regards,
herman
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QuickAFL & Barindex by Tomasz
Herman,
Because you probably will ask this question anyway:
what if you really, really have to use array index operator and barindex?
That's simple too. As you can see from the picture below actual array item
corresponding to bar index can be found this way:
Bar Index 0 1 2 3 4 5 6 7 8 9 10 11 12
Array element 0 1 2 3 4 5
bi = BarIndex();
item = SelectedValue( bi ) - bi[ 0 ];
Title = NumToStr(MyCustomArray[ item ] ,1.2);
Best regards,
Tomasz Janeczko
amibroker.com
Herman,
Short story:
Your code does NOT really need index addressing, setbarsrequired, barindex
at all.
Somehow you managed to complicate thing when it is very, very simple and can
be coded in 2 lines:
MyCustomArray = EMA(C,3);
Title = "NumberFromMyCustomIndicator ="+NumToStr(MyCustomArray ,1.2);
Long story:
Take a look at picture below:
Bar Index 0 1 2 3 4 5 6 7 8 9 10 11 12
Array element 0 1 2 3 4 5
You see: Bar index represents ENTIRE data set you have.
Array may be actually smaller than your entire data set (if visible area for
indicator is small) and
may have LESS elements than entire data set you have.
Array in indicator builder when QuickAFL is on may include only visible part
(plus some extra bars).
Now selected bar is shown with red color. As you can see although it has a
bar index of 8,
the actual array element has the number of 4.
That's why you can not use barindex to address your arrays directly.
Instead use SelectedValue directly on array, by simply typing:
MyCustomArray = EMA(C,3);
NumberFromMyCustomIndicator = SelectedValue( MyCustomArray );
It is way simpler than your code and works always and you do not need to
bother about quickafl and setbarsrequired at all.
In fact NumToStr already performs "selected value" so you code can be
simplified to 2 lines:
MyCustomArray = EMA(C,3);
Title = "NumberFromMyCustomIndicator ="+NumToStr(MyCustomArray ,1.2);
It performs as you wanted it to perfom and takes 2 lines instead of 5.
It is all actually simpler than you think.
Best regards,
Tomasz Janeczko
amibroker.com
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-----Original Message-----
From: Stephane Carrasset [mailto:s.carrasset@xxxxxxxxxxx]
Sent: Wednesday, September 15, 2004 12:53 PM
To: amibroker@xxxxxxxxxxxxxxx
Subject: [amibroker] loops and lastvalue part I
Hello all,
that's many times that I ask me if the usage of lastvalue in a loop
returns expected results, as lastvalue returns the scalar value of
the last bar of an array and can be used in a loop.
the example below confirms, I suppose, that we must take care of
lastvalue in a loop.
I think I am right?
Stephane
myMFI = MFI( 14 );
myRSI=RSI(14);
average=averageLV=0;
for( i = 0 ; i < BarCount; i++ )
{
if( myMFI[i] > myRsi[i] )
average ++;
if( myMFI[i] > LastValue(RSI(14)) )
averageLV ++;
result[i]=average;
resultLV[i]=averageLV;
}
Plot(result,"",2,1);
Plot(resultLV,"",3,1);
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