1. That line he put in works; however if you really want 21 bars instead of
22 you have to replace < by < =.
There is another solution as well using SetBarsRequired (see 5. below)
2. Plot( IIf( BarIndex() >= BarCount - EMABarsVisible21, EMA( C,21), Null ),
"", colorViolet,styleNoLabel |5 );
Tomasz will tell you that the equation works, and that the loop doesnt do
anything except for slowing you down. That is incorrect: Without the loop
this equation in 5.2+ does plot all points instead of (21) (see below). In
addition, after the Reset all, there is no performance degradation. I dont
know why it works, only that it does. Verify it yourself: it is a 15 sec
procedure. (I am not proposing this since there are better ways now)
3. The mal-aligned loop works for all 5.2 and up versions as well as for
5.3. As an aside, it has the added advantage that it displays not just the
end values but the last values on the RHS of each Visible Range.
4.Plot(IIF(BarIndex()
.. does not work for 5.2 and up versions. It does
work for 5.3 and its last precursor (5.296). I found that out yesterday
since I dont use it (irreversible file format)
I did some additional testing and tried to get an idea what caused this
behavior and found:
5. If you add SetBarsRequired(-2,-2); the code below works for all 5.2 and
up versions
SetBarsRequired(-2,-2 ); //SetBarsRequired(sbrAll,sbrAll )
Plot( IIf( BarIndex() >= BarCount - 5, EMA( C,21), Null ), "",
colorBlue,styleNoLabel |5 );
Now with respect to your question about cause:
6. a. Plot(IIF(BarIndex()
.. alone does not work for 5.2+ but does in 5.3
b.With SetBarsRequired Plot(IIF(BarIndex()
.. also works in 5.2 and up
This suggests that QuickAFL, what I believe is on until it is turned off by
SetBarsRequired has something to do with it. I have a feeling that changes
made in QuickAFL for 5.3 rendered use of SetBarsRequired in front of Plot(
IIf( BarIndex
unnecessary in 5.3. Also I have had a few times that the
values changed when adding setBarsRequired, even though the code didnt seem
to require it (loops,scripts,DLLs). So if I have any questions about the
results, the first thing I do is adding SetBarsRequired and look at its
impact.
From: [email protected] [mailto:[email protected]] On Behalf
Of progster01
Sent: Saturday, April 24, 2010 3:25 AM
To: [email protected]
Subject: [amibroker] Re: Restricted Plot; Final test procedure; mainly a
response to Mike and Tomasz
The working two-liner is great, and very clear to understand as given:
bi = BarIndex();
Plot( IIf( bi < LastValue( bi ) - 21, Null, EMA( C, 21 ) ), "EMA", colorRed
);
But why doesn't this other code that was discussed:
Plot( IIf( BarIndex() >= BarCount - EMABarsVisible21, EMA( C,21), Null ),
"", colorViolet,styleNoLabel |5 );
successfully accomplish the same thing?
Understanding the difference, exactly, is much to be desired, IMO. Knowing
the platform deeply enough to understand and avoid such pitfalls is the goal
of many of us.
I ask here on the list so that all may benefit from any answer that might be
provided.
--- In [email protected] <mailto:amibroker%40yahoogroups.com> ,
Tomasz Janeczko <gro...@...> wrote:
> Original question was:
> > How to plot 21 days EMA only for the last 21 bars.
>
> And the answer is TWO liner:
>
> |bi = BarIndex();
> Plot( IIf( bi < LastValue( bi ) - 21, *Null*, EMA( *C*, 21 ) ), "EMA",
> *colorRed* );|
>
> And it works in ALL AmiBroker versions.
