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Yes, and I now have a clarification. If I place just the following
code in an indiciator and click Apply:
aVisBars = Status("barvisible");
nLastVisBar = LastValue(Highest(IIf(aVisBars, BarIndex(), 0)));
_TRACE(" - Before -");
_TRACE("Last visible bar: " + nLastVisBar);
_TRACE(" - After - ");
I will see the following debug output:
[3552] - Before -
[3552] Last visible bar: 0
[3552] - After -
[3552] - Before -
[3552] Last visible bar: 958
[3552] - After -
[3552] - Before -
[3552] Last visible bar: 958
[3552] - After -
[3552] Last visible bar: 958
Notice that for the very first instance of output, the value is 0,
and in subsequent outputs, it has the correct, non-zero value. This
is all from one click of Apply on one chart from within the AFL
editor. For whatever reason, the output makes it appear that the code
is either initialized once and then executed three times, or just
executed four times. I don't understand the multiple lines of output,
but it does tell me why I perceive that my code has a bug. The
variable is used in a loop -- and I get an array out of bounds error.
Apparently I need to check the value before entering the loop so that
when whatever initialization is being performed, etc., I don't get
the error.
Incidentally, if I scroll to another chart, I then see the following
new lines in the trace output:
[3552] Last visible bar: 958
[3552] Last visible bar: 958
[3552] - Before -
[3552] Last visible bar: 962
[3552] - After -
[3552] - Before -
[3552] Last visible bar: 958
[3552] - After -
[3552] Last visible bar: 958
Note that after the first execution, which resulted from hitting
apply and not from scrolling to a new chart -- is this the
compilation of the code? -- nLastVisBar has the correct value right
from the get go. There's not illusory 0 value that appears and then
goes away.
This may be more detail than most readers are interested in seeing,
but it does explain the array out of bounds error. If TJ would like
to shed any light on the trace output, that would be interesting and
appreciated. Something I really find interesting are the sets of
output that do not include the pure text output -- only the lines
that involve a variable. So what represents the true, or official,
execution of the indicator code? I don't know for sure, but I would
gather it's the last instance of output.
Gordon
--- In amibroker@xxxxxxxxxxxxxxx, "William Peters"
<williampeters@xxxx> wrote:
> Gordon,
>
> This code plots the highest visible barindex. This is a zero based
array so
> the last bar will be 1 less than the total number of quotes.
>
> BV = Status("barvisible");
> HVBIndex = LastValue( Highest( ValueWhen(BV,BarIndex()) ), True );
> Plot(HVBIndex ,"HVBIndex",1,styleLine);
>
> Regards,
> William Peters
> www.amitools.com
>
> -----Original Message-----
> From: Gordon [mailto:amibroker@x...]
> Sent: Monday December 8, 2003 3:56 PM
> To: amibroker@xxxxxxxxxxxxxxx
> Subject: [amibroker] Bar index of last visible bar
>
>
> I'm writing an indicator. Searching the newsgroup archives, I found
> (posted 3/2/2003) what I thought was my answer to determining the
bar
> index of the last visible bar:
>
> "
> Tomasz posted this to the member section a while ago......
>
> barvisible = Status("barvisible");
> r = RSI( 14 );
> maxr = LastValue( Highest( IIf( barvisible, r, 0 ) ) );
> "
>
> So it would seem that:
>
> aVisBars = Status("barvisible");
> nLastVisBar = LastValue(Highest(IIf(aVisBars, BarIndex(), 0)));
>
> should work, where nLastVisBar holds the barindex of the last
visible
> bar. However, nLastVisBar always has a value of 0 when I access it
in
> code. Also, the help says that Highest returns a NUMBER, but it
seems
> to be an ARRAY. Without the use of the LastValue() function, I can't
> use nLastVisBar in an IF statement.
>
> That way I initialize nLastVisBar, btw, is at the top of an
> indicator. The value is then used to control a for loop.
>
> If anyone can see the error I must be missing, I would appreciate
it.
>
> Gordon
>
>
>
>
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