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[amibroker] Re: Optimize function



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--- In amibroker@xxxxxxxxxxxxxxx, "willem1940" <w.j.a.struyck@xxxx> 
wrote:
> Picking up your "invitation" under PS I wondered if the suggestion 
> below is "do-able" in AB.

See my previous ref Re:Walk-forward optimization. You may define 
starting date, ending date, duration etc.
> 
> I have studied the earlier exchange of messages on walk-forward 
> methods but from the contenst I could not construct the way I carry 
> out the walk-forward exercise; trying to imitate as much as 
possible 
> the reality.
> The sequence I follow is:
> -	establish the period for the optimization in nr of bars 
> (period)
> -	set the range to the point in time where the first 
> optimization should end say one week from now: (endtime)
> -	optimize
> -	place parameters in formula
> -	move the range an agreed number of bars (bars) nearer the 
> last bar in the system  (endtime - bars)
> -	backtest for this period
> -	copy the results to Excell
> -	set the range to the point in time where the second 
> optimization should being (endtime - bars)
> -	optimize
> -	place parameters in formula 
> -	move the range again an agreed number of bars nearer the last 
> bar in the system  (endtime - bars - bars)
> -	backtest for this period
> -	copy the results to Excell
> -	set the range to the point in time where the third 
> optimization should being endtime - bars - bars)
> -	optimize
> -	etc.
> 
> Subsequently in Excell I combine the entries in one trading track 
> record by deleting the overlap in time leaving every time the last 
> entries, so the true result of the day after the op[timization 
> finished.
>  
> As you can imagine this is tedious work and of course I wondered if 
> with the new functions in AB this can be done automatically. 
> Unfortunately I am not  a programmer otherwise I would give it a 
try.

I am not a programmer either. I use AFL vehicle, it is very 
interesting for Stock analysis.

> Willem Jan
> 
> 
> --- In amibroker@xxxxxxxxxxxxxxx, "DIMITRIS TSOKAKIS" 
<TSOKAKIS@xxxx> 
> wrote:
> > "I don't know whether AA's optimization process works like the 
> > Optimize function in IB but suspect it might."
> > Bill,
> > There is a [probable] confusion here:
> > From the definition in 4.40 users guide, 
> > "With normal backtesting, scanning, exploration and comentary 
modes 
> > the optimize function returns default value, so the above 
function 
> > call returns default; "
> > In other words, a code
> > p=Optimize("p",40,10,50,10);
> > y=StochD(p);
> > Plot(y,"y",1,1);
> > would produce the graph of StochD(40) and nothing more.
> > 
> > "However, the basic question is whether k was optimized for the 
> > entire dataset or just 2002."
> > The described code [as the older ref] does exactly this : It 
> > optimizes k for the restricted period.
> > "As far as I can tell it is for the entire dataset, reflecting 
the 
> > fact that the Optimize function does not have a time frame 
argument
> > (s) and, therefore, no way to limit its operation to a specified 
> time 
> > window."
> > Since Optimize function does not have time frame arguments, there 
> is 
> > *another* way to limit its operation : Apply Optimization to the 
> > specified time window and you have the required result. Try any 
AA 
> > test and you will see.
> > "As a result, I wondered if anyone had a workaround that would 
> force 
> > the Optimize function to only use data within a specified time 
> frame."
> > The described codes do this job. You may disagree with the logic, 
> but 
> > the result is exactly the requested.
> > Some AFL functions/procedures are limited to a range of 
properties, 
> > clealy exposed in the definitions. When we need something out of 
> > these limitations, we have to use another way.
> > There was a similar discussion with variable periods. Some AFL 
> > functions do accept variable period, some others dont. If we want 
a 
> > variable per in EMA(C,per), we can not act directly, EMA does not 
> > accept variable period. We have to find another, indirect way, to 
> do 
> > it.
> > You ask from Optimize function some results out of its [current] 
> > definition . It is not possible. [Imagine the opposite !!!AFL 
would 
> > become an unreliable set of functions !!!]
> > IMO, the only way to get a result through AFL is to follow the 
> > definitions "mot a mot". Any other attempt would cause mistakes. 
> > Sometimes the mistake is prevented by the AFL Error window, but 
not 
> > always.
> > There is no code mistake in the lines
> > p=Optimize("p",40,10,50,10);
> > y=StochD(p);
> > Plot(y,"y",1,1);
> > but, dont expect from these lines an optimization procedure 
similar 
> > to the OPTIMIZE button, it is N/A [yet]
> > I hope it is clear.
> > Thank you for the interesting dialogue, I have nothing more to 
add.
> > Dimitris Tsokakis
> > PS For "similar" IB procedures we may use for loops and 
practically 
> > have the same results with optimization procedure. I have solved 
> the 
> > general problem, I think it may be applied to any case, but it 
> would 
> > be better to ask a specific question.
> > 
> > --- In amibroker@xxxxxxxxxxxxxxx, "wavemechanic" <wd78@xxxx> 
wrote:
> > > 
> > > ----- Original Message ----- 
> > > From: "DIMITRIS TSOKAKIS" <TSOKAKIS@xxxx>
> > > To: <amibroker@xxxxxxxxxxxxxxx>
> > > Sent: Friday, September 12, 2003 2:18 PM
> > > Subject: [amibroker] Re: Optimize function
> > > 
> > > 
> > > Bill,
> > > 
> > > (Initial message)
> > > k=Optimize("k",40,30,50,10);
> > > > d2002=DateNum()>=1020101 AND DateNum()<1030101;
> > > > LastTradingBar=(d2002==0 AND Ref(d2002,-1))*DateNum();
> > > > Buy=d2002*Cross(StochD(),k);
> > > > Sell=d2002*Cross(StochD(),70) OR DateNum()==LastTradingBar;
> > > >
> > > > Hit now Optimize for
> > > > *current stock
> > > > *all quotations
> > > > AA will see only 2002 dates.
> > > 
> > > (Second message)
> > > Optimization, by itself, has no restriction property.
> > > When we say Optimize, the AA will check the settings or whatever
> > > overwrites the settings.
> > > In my example, the settings are "all quotations".
> > > But, the trading rules are restricted by definition:
> > > Buy=d2002*Cross(StochD(),k);
> > > Sell=d2002*Cross(StochD(),70) ;
> > > This d2002 is a binary quantity, equal to 1 or 0, as definrd in 
> the
> > > previous lines. The d2002*something will give something or 0.
> > > Consequently, when d2002 is true, the AA will read
> > > Buy=Cross(StochD(),k);
> > > Sell=Cross(StochD(),70);
> > > and when d2002 is false, the AA will read
> > > buy=0;
> > > sell=0;
> > > Make a scan for all quotations to see. The trades will be for 
2002
> > > dates only.
> > > In other words, in order to optimize from datenum1 to datenum2, 
> just
> > > define trades for this period only and thatīs it !!
> > > 
> > > As I mentioned to Leo a few minutes ago, I am not using AA but 
> > rather
> > > generating charts with IB.  I don't know whether AA's 
> optimization 
> > process
> > > works like the Optimize function in IB but suspect it might.  
> With 
> > that
> > > uncertainty as background, I think we are talking about apples 
> and 
> > oranges.
> > > Yes your code will produce trades only in 2002 with an 
optimized 
> > value for k
> > > (optimized in code from first message), and I use other code at 
> the 
> > present
> > > time to achieve similar results.  However, the basic question 
is 
> > whether k
> > > was optimized for the entire dataset or just 2002.  As far as I 
> can 
> > tell it
> > > is for the entire dataset, reflecting the fact that the 
Optimize 
> > function
> > > does not have a time frame argument(s) and, therefore, no way 
to 
> > limit its
> > > operation to a specified time window.  As a result, I wondered 
if 
> > anyone had
> > > a workaround that would force the Optimize function to only use 
> > data within
> > > a specified time frame.  One could, use brute force and 
manually 
> > change the
> > > number of bars and time period loaded, but that is too awkward 
to 
> be
> > > seriously considered.
> > > 
> > > 
> > > --- In amibroker@xxxxxxxxxxxxxxx, "wavemechanic" <wd78@xxxx> 
> wrote:
> > > >
> > > > ----- Original Message ----- 
> > > > From: "DIMITRIS TSOKAKIS" <TSOKAKIS@xxxx>
> > > > To: <amibroker@xxxxxxxxxxxxxxx>
> > > > Sent: Friday, September 12, 2003 12:48 PM
> > > > Subject: [amibroker] Re: Optimize function
> > > >
> > > >
> > > > > Bill,
> > > > > I have posted in the past the walk-forward optimization.
> > > > > Here is the basic principle, for a restricted period 
> > optimization
> > > > > [year2002 in the example]
> > > >
> > > > If I correctly understand, optimization of k is still being
> > > established on
> > > > the entire dataset, rather than only on 2002 data.  Right?  
If 
> so,
> > > how would
> > > > you restrict Optimize to operate only in 2002?
> > > >
> > > > > of a Stochastic o/b, o/s system :
> > > > >
> > > > > k=Optimize("k",40,30,50,10);
> > > > > d2002=DateNum()>=1020101 AND DateNum()<1030101;
> > > > > LastTradingBar=(d2002==0 AND Ref(d2002,-1))*DateNum();
> > > > > Buy=d2002*Cross(StochD(),k);
> > > > > Sell=d2002*Cross(StochD(),70) OR DateNum()==LastTradingBar;
> > > > >
> > > > > Hit now Optimize for
> > > > > *current stock
> > > > > *all quotations
> > > > > AA will see only 2002 dates.
> > > > > It is important to exit any open trade by the end of the 
test
> > > period,
> > > > > else the last probable Open trade will last for ever !!
> > > > > The solution is that{  OR DateNum()==LastTradingBar } 
> statement.
> > > > > Dimitris Tsokakis
> > > > > --- In amibroker@xxxxxxxxxxxxxxx, "wavemechanic" <wd78@xxxx>
> > > wrote:
> > > > > >
> > > > > > ----- Original Message ----- 
> > > > > > From: "Stephane Carrasset" <nenapacwanfr@xxxx>
> > > > > > To: <amibroker@xxxxxxxxxxxxxxx>
> > > > > > Sent: Friday, September 12, 2003 11:55 AM
> > > > > > Subject: [amibroker] Re: Optimize function
> > > > > >
> > > > > >
> > > > > > > Bill,
> > > > > > >
> > > > > > > do you mean if you Backtest for example NDX on the last 
> 500
> > > bars
> > > > > > > do you want optimize an indicator on the 500-400 bars?? 
> then
> > > keep
> > > > > the
> > > > > > > optimized value on the 400-1 bars ??
> > > > > >
> > > > > > I was not thinking of that, but your scenario is along 
the 
> > same
> > > > > lines and
> > > > > > would be a another important option.  I was actually 
> thinking 
> > of
> > > > > the problem
> > > > > > from 180 degrees around.  Specifically, for a dataset of, 
> for
> > > > > example, 1000
> > > > > > bars optimize only over the last 500 and display the 
equity
> > > curve
> > > > > for that
> > > > > > range.  It is possible to only consider (and display) the 
> > equity
> > > > > for a
> > > > > > specified number of bars (e.g., the last 500 bars), but I 
> > don't
> > > see
> > > > > how to
> > > > > > restrict optimization to those bars.  Certainly not with 
the
> > > > > available
> > > > > > arguments for Optimize.
> > > > > >
> > > > > > >
> > > > > > > Stephane
> > > > > > >
> > > > > > > > It is my understanding that the Optimize function 
> operates
> > > on
> > > > > all
> > > > > > > data.  So,
> > > > > > > > for example, if one is looking at equity for a 
portion 
> of
> > > the
> > > > > data
> > > > > > > (e.g.,
> > > > > > > > Equity(0, 1, 100) Optimize still operates on all 
data.  
> > Does
> > > > > anyone
> > > > > > > have a
> > > > > > > > work-around that will force Optimize to only consider 
a
> > > > > specified
> > > > > > > range of
> > > > > > > > data?
> > > > > > > >
> > > > > > > > Thanks.
> > > > > > > >
> > > > > > > > Bill
> > > > > > >
> > > > > > >
> > > > > > >
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