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Ok, thanks again. What you are saying is very clear. However, in my
case I am writing my own indicators that, for statistical reasons, may
need to look back into the price history an arbitrary amount of time.
The amount of time is a percentage of the available data in the
database. I am not using any AmiBroker functions that have a
pre-configured look back requirement (such as a moving average). I
require looping over all available data and performing calculations.
So, knowing that the BarCount may not have a direct relationship to the
number of bars in the database, unless I set it explicitly solves my
issue. Using SetBarsRequired seems to work well. Thanks again.
Tomasz Janeczko wrote:
Hello,
Not necesarily last N bars because you can scroll back to say first year visible from those
20 years and then it would represent first N bars.
As for lookback - it is automatically calculated by AmiBroker based on functions you use.
Use Tools->"CHECK" function in the AFL editor to find out how many bars before first visible
and after last visible are required. It was explained on this group a couple of times already.
For example if your formula is
MA( C, 50 ) > C and MA( C, 150 ) > C;
AmiBroker will use 230 bars PRIOR to first visible bar (200 for averages and 30 "extra" padding that
is always added).
Best regards,
Tomasz Janeczko
amibroker.com
----- Original Message -----
From: "oneklema" <andy@xxxxxxxxxxx>
To: <amibroker@xxxxxxxxxxxxxxx>
Sent: Friday, September 07, 2007 4:42 PM
Subject: [amibroker] Re: Simple question about BarCount
Thanks for your quick help Tomasz. So, BarCount represents the last N
bars, where N simply varies depending on the zoom factor.
I understand what you are saying with your example of the 20 years of
data. But also, I can certainly conceive of an indicator (or script)
that may want a "lookback" to be longer than and independent from the
zoom factor. Which is why, I'm sure, there is the SetBarsRequired()
function.
--- In amibroker@xxxxxxxxxxxxxxx, "Tomasz Janeczko" <groups@xxx> wrote:
BarCount does not represent number of bars in the DATABASE,
but in the ARRAYs in current execution.
The arrays have DYNAMIC size depending on zoom factor. That's why
BarCount may and will vary.
For example if you have 20 years of data and you are watching just
the last year
AmiBroker does not need and does not use all bars in the database to
calculate
indicators for last year.
It uses last year only PLUS some previous bars required to
"stabilise" indicator values.
The number of extra bars depends on functions you use in the formula.
If you want to use truly all bars you need to use SetBarsRequired
function:
http://www.amibroker.com/f?setbarsrequired
Best regards,
Tomasz Janeczko
amibroker.com
----- Original Message -----
From: "oneklema" <andy@xxx>
To: <amibroker@xxxxxxxxxxxxxxx>
Sent: Friday, September 07, 2007 3:45 PM
Subject: [amibroker] Simple question about BarCount
I have what should be a simple question about BarCount but cannot get
a definitive answer from the AB documentation. FYI, I am working on
daily data.
What exactly does BarCount represent? The AB help says:
BarCount constant gives the number of bars in array (such as Close,
High, Low, Open, Volume, etc). Array elements are numbered from 0
(zero) to BarCount-1.
So, I understand that it is the size of the arrays (I'm an old C
programmer). But, I assumed that if I have a loop such as:
for (i = 0; i < BarCount, i++)
{
do work on C[i];
}
I would do work on every Close value that is *in the database for the
symbol that is opened*. But, it does not seem to work this way (?).
When I print out the value of BarCount, I notice that it changes as I
change the Zoom factor (i.e., clicking +,-). And, the only way to get
BarCount to reflect all data is to zoom as as far as it can go. So, I
thought maybe it represents the number of bars displayed as adjusted
by the zoom. But, from a visual inspection, it is obviously not that
(maybe related, but not exact).
Is there any way to operate on symbol data for all data that has been
loaded into the database, regardless of the zoom factor?
Please note that this group is for discussion between users only.
To get support from AmiBroker please send an e-mail directly to
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Yahoo! Groups Links
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To get support from AmiBroker please send an e-mail directly to
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For NEW RELEASE ANNOUNCEMENTS and other news always check DEVLOG:
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For other support material please check also:
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Yahoo! Groups Links
Please note that this group is for discussion between users only.
To get support from AmiBroker please send an e-mail directly to
SUPPORT {at} amibroker.com
For NEW RELEASE ANNOUNCEMENTS and other news always check DEVLOG:
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For NEW RELEASE ANNOUNCEMENTS and other news always check DEVLOG:
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For other support material please check also:
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