Hello,
Clearly you did not read the manual of Wealth-Lab carefully enough.
check page 240 of their manual and you will read the following:
"The Peak function never "looks ahead" in time, but always returns the
Peak value as it
would have been determined as of the specified bar. *For this reason,
the return value of
the Peak function will lag, and report peaks a few bars later than they
actually occurred
in hindsight.*"
What they are trying to say is that the peak function DOES look into the
future but they
internally DELAY the output of their Peak so the last leg of minimum
percentage is formed.
Such delay makes it unprofitable but well... that is not mentioned in
their manual.
AmiBroker does NOT delay the Peak output as the primary purpose of
Peak/Trough and all
Zig-zag family is PATTERN detection and not trading systems.
It makes sense to have delay-free Peak because DELAYED Peak function can
not be "undelayed" back.
It is possible and quite easy in fact to create "WL-style" delayed peak
by simply delaying AFL's Peak/Trough/Zig zag
and it is presented in detail here:
http://www.amibroker.com/members/traders/11-2003.html
(for more details about that see ZigZag Trend Indicator in Nov 2003
issue of Stocks&Commodities)
Best regards,
Tomasz Janeczko
amibroker.com
On 2010-04-26 01:43, jhnlmn wrote:
Thank you for your response.
In essence, you are saying that I cannot use Tsokakis example
(and many others from the Amibroker and Metastock libraries)
without a significant rewriting.
I am new to Amibroker. I was looking for a good trendline recognition script
and stumbled on Amibroker. So, I downloaded a trial version to quickly test
these scripts.
So, I need to decide whether it is worse the effort to rewrite these scripts
for Amibroker or go back to Wealth-Lab, which I was using before.
I am surprised that PeakBars and TroughBars are looking into the future in
Amibroker.
It is not the case in WL. These are pretty simple functions - they just need to
find min or max before a reversal.
Why would Amibroker look into the future in this case?
Now about replacing SelectedValue/LastValue.
I tried to fix "Historical Trendlines and Breakouts" script
by wrapping part of the script in for(i = 0; i< BarCount; i++) loop and then
replacing:
...
pS = TroughBars( s1, per, 1 ) == 0;
endt=SelectedValue(ValueWhen( pS, x ,1));
startt=SelectedValue(ValueWhen( pS, x ,2));
dtS =endt-startt;
endS = SelectedValue((ValueWhen( pS, s1,1) ));
startS = SelectedValue(( ValueWhen( pS, s1 ,2)));
aS = (endS-startS)/dtS;bS = endS;
trendlineS = aS * ( x -endt ) + bS;//SUPPORT LINE
...
Plot(IIf(x>=first -d AND x<=Last+d,trendlineS,-
1e10),"Support",colorBrightGreen,1);
by
pS = TroughBars( s1, per, 1 ) == 0;
troughBarIdxLast = ValueWhen( pS, x ,1);
troughBarIdxBeforeLast = ValueWhen( pS, x ,2);
troughBarValueLast = ValueWhen( pS, s1, 1);
troughBarValueBeforeLast = ValueWhen( pS, s1, 2);
...
for(i = startBar; i< lastBar; i++)
{
endt= troughBarIdxLast[i];
startt = troughBarIdxBeforeLast[i];
if(prevEndTrendlineS != endt)
{
prevEndTrendlineS = endt;
dtS = endt - startt;
endS = troughBarValueLast[i];
startS = troughBarValueBeforeLast[i];
aS = (endS - startS) / dtS;
bS = endS;
trendlineS = aS * ( x - endt ) + bS;//SUPPORT LINE
Plot(IIf(x>= startt - d AND x<= endt + d, trendlineS, -1e10),
"Support", colorBrightGreen, 1);
}
...
}
Is it the right approach to rewriting SelectedValue or LastValue scripts for a
continuous drawing or backtesting?
(Below is the entire rewritten script).
Thank you
John
x = Cum(1);
per = 3;// CALIBRATE THE ZIG() SENSITIVITY
s1=L;
s11=H;
pS = TroughBars( s1, per, 1 ) == 0;
troughBarIdxLast = ValueWhen( pS, x ,1);
troughBarIdxBeforeLast = ValueWhen( pS, x ,2);
troughBarValueLast = ValueWhen( pS, s1, 1);
troughBarValueBeforeLast = ValueWhen( pS, s1, 2);
pR = PeakBars( s11, per, 1 ) == 0;
peakBarIdxLast = ValueWhen( pR, x, 1);
peakBarIdxBeforeLast = ValueWhen( pR, x, 2);
peakBarValueLast = ValueWhen( pR, s11, 1);
peakBarValueBeforeLast = ValueWhen( pR, s11, 2);
startBar = Status("FirstVisibleBar");
lastBar = Status("LastVisibleBar");
_TRACE("Startbar:"+startBar);
_TRACE("Lastbar:"+lastBar);
prevEndTrendlineS = -1;
prevEndTrendlineR = -1;
d=10;// INCREASE d TO EXTEND THE LINES
Years=Year();
Months=Month();
Days=Day();
//color =
for(i = startBar; i< lastBar; i++)
{
color[i] = colorBlack;
}
for(i = startBar; i< lastBar; i++)
{
endt= troughBarIdxLast[i];
startt = troughBarIdxBeforeLast[i];
if(prevEndTrendlineS != endt)
{
prevEndTrendlineS = endt;
dtS = endt - startt;
endS = troughBarValueLast[i];
startS = troughBarValueBeforeLast[i];
aS = (endS - startS) / dtS;
bS = endS;
trendlineS = aS * ( x - endt ) + bS;//SUPPORT LINE
bearishbreakout = x> endt AND x< endt + d AND Cross(trendlineS, C);
color = IIf (bearishbreakout,colorRed,color);
Plot(IIf(x>= startt - d AND x<= endt + d, trendlineS, -1e10),
"Support", colorBrightGreen, 1);
}
endt1 = peakBarIdxLast[i];
startt1 = peakBarIdxBeforeLast[i];
if(prevEndTrendlineR != endt1)
{
prevEndTrendlineR = endt1;
dtR =endt1-startt1;
endR = peakBarValueLast[i];
startR = peakBarValueBeforeLast[i];
aR = (endR-startR)/dtR;
bR = endR;
trendlineR = aR * ( x -endt1 ) + bR;//RESISTANCE LINE
bullishbreakout = x> endt1 AND x< endt1 + d AND Cross(C,trendlineR);
color = IIf (bullishbreakout,colorGreen,color);
Plot(IIf(x>= startt1 - d AND x<= endt1 + d, trendlineR, -1e10),
"Resistance", colorRed, 1);
}
}// for(i = startBar; i< lastBar; i++)
Plot(C,"Close",color,64);
------------------------------------
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