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Re: [amibroker] Re: Help understanding array processing



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Barry:
 
Does this do what you want?
 
Sell = ... ;
lowestLowSinceSell = LowestSince( Sell, L, 1 );
 
Bill
----- Original Message -----
From: Barry
Sent: September 21, 2009 7:46 PM
Subject: [amibroker] Re: Help understanding array processing

What I am trying to do is find the lowest low from the last sell so I can calculate a buy point above that low, or below the high for a sell.  The first problem I ran into was what to do before the first trade.  I used highest and lowest but afterward I wanted to use hhv and llv.  Ami goes nuts when I try to reference buy and sell before they are ever set.  So barssince returned nulls for all bars. 

Marcin told me I had to use loops.  I remember loops really slowing things down so I tried to do it another way. I tried to set my test hi and low arrays one step at a time.  The hi and lo just followed the close. I was expecting it to operate one bar at a time. That did not work as you pointed out. 
 
I finally said to heck with it and used loops. I am used to arrays in C++ and I really get screwed up with Ami's arrays. Do you know if looping slows the process down a lot or does Ami only go back far enough to load the indicators correctly?  I remember seeing something like that.

Thanks Steve,
Barry

--- In amibroker@xxxxxxxxxxxxxxx, "Steve Dugas" <sjdugas@xxx> wrote:
>
> Hi - I think you have run into the old "recursive" problem. In the first
> line...
>
> theHi[0] = C[0];
>
> you set only the first bar of the Hi to the close. Don't know what the rest
> of the array is offhand, AB may initialize it to zero or null or something,
> otherwise I would think the values are whatever was previously in memory.
> Then the second line operates on the entire array at once so it will use
> whatever those values of theHi are at that point, it will *not* do one bar
> at a time and then refer back to that bar, I think that is one reason why TJ
> added looping.
>
> It looks like you are looking for the highest Close in the array, could you
> just use
>
> Highest( Close)  ?
>
> Steve
>
> ----- Original Message -----
> From: "Barry" <razzbarry@xxx>
> To: <amibroker@xxxxxxxxxxxxxxx>
> Sent: Monday, September 21, 2009 5:25 PM
> Subject: [amibroker] Help understanding array processing
>
>
> >I am not new to Ami, been using it since 2003.  But at times the array
> >processing drives me nuts.  I tried to use barssince and looked at the buy
> >and sell arrays before they were set. so they were still nulls even when I
> >initialized them to buy = sell = 0;
> >
> > But to try to understand what the arrays were doing I wrote a stupid
> > little program to see what was going on. The code is below.
> >
> > What I am trying to do is save the highest hi in an array called theHi.  I
> > set the first cell in theHi to the value of in the first cell of the
> > close.  Then I compare them but theHi follows the close even when the
> > close goes down.
> >
> > Then I wrote the same function in a for loop and it works fine.
> >
> > Then I added the formula to Excel and it worked correctly.
> > =IF(C3>D2,C3,D2) where C has the close and D the hi array values. Here I
> > also set the hi in cell 2 to the first value of Close.
> > SO excel works fine with the same formula as Afl but Afl fails.
> >
> > I must be missing something really basic. Can anyone tell me why Ami won't
> > allow me to scan through the close array and save the high?
> >
> > Thanks,
> > Barry
> >
> > _SECTION_BEGIN("TestBarsSince");
> >
> > _N(Title = StrFormat("BarsSince test - {{INTERVAL}} {{DATE}} \nOpen %g, Hi
> > %g, Lo %g, Close %g (%.1f%%) Vol " +WriteVal( V, 1.0 ) +" {{VALUES}}", O,
> > H, L, C, SelectedValue( ROC( C, 1 )) ));
> >
> > Plot( C, "Close", ParamColor("Color", colorBlack ), styleNoTitle |
> > styleBar  ); // shows all style options
> >
> > theHi[0] = C[0];
> > theHi = IIf(C > Ref(theHi, -1), C, Ref(theHi, -1));
> > Plot(theHi, "\nTheHi", colorBlue  );
> >
> > forHi[0] = C[0];
> > for (i = 1; i < BarCount; ++i)
> > {
> > if(C[i] > forHi[i-1]) forHi[i] = C[i]; else forHi[i] = forHi[i-1];
> > }
> >
> > Plot(forHi, "\nHi with for loop", colorGreen);
> >
> > _SECTION_END();
> >
> >
> >
> > ------------------------------------
> >
> > **** IMPORTANT PLEASE READ ****
> > This group is for the discussion between users only.
> > This is *NOT* technical support channel.
> >
> > TO GET TECHNICAL SUPPORT send an e-mail directly to
> > SUPPORT {at} amibroker.com
> >
> > TO SUBMIT SUGGESTIONS please use FEEDBACK CENTER at
> > http://www.amibroker.com/feedback/
> > (submissions sent via other channels won't be considered)
> >
> > For NEW RELEASE ANNOUNCEMENTS and other news always check DEVLOG:
> > http://www.amibroker.com/devlog/
> >
> > Yahoo! Groups Links
> >
> >
> >
> >
>




------------------------------------

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**** IMPORTANT PLEASE READ ****
This group is for the discussion between users only.
This is *NOT* technical support channel.

TO GET TECHNICAL SUPPORT send an e-mail directly to
SUPPORT {at} amibroker.com

TO SUBMIT SUGGESTIONS please use FEEDBACK CENTER at
http://www.amibroker.com/feedback/
(submissions sent via other channels won't be considered)

For NEW RELEASE ANNOUNCEMENTS and other news always check DEVLOG:
http://www.amibroker.com/devlog/





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