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Hi Mike, you're perfectly right.
I managed to get a solution with this which looks the same as yours.
thanks for every suggestion.
paolo
// EmptySymbols finder
// retrive comma-separated list of symbols
// from Group 0
list = CategoryGetSymbols(categoryGroup, 0);
Count = 0;
for( i = 0; ( sym = StrExtract( list, i ) ) != ""; i++ )
{
SetForeign(sym);
myforeign = C;
RestorePriceArrays();
//if the symbol is empty Count is not increased
Count = Count + IIf (IsNull(myforeign), 0, 1);
_TRACE("symbol " + sym);
_TRACE("Count " + Count);
_TRACE("IsNull " + IsNull(myforeign));
}
Plot(Count, "Count", colorRed, styleLine | styleThick);
--- In amibroker@xxxxxxxxxxxxxxx, "Mike" <sfclimbers@xxx> wrote:
>
> I think that your code is now wrong. It was correct the way you had
it
> before.
>
> Consider the scenario where you have 10 symbols, and any number of
the
> initial symbols have any number of NULLs, but the last symbol does
not
> have any nulls.
>
> By the end of your loop, the variable i will be 9 (e.g. 0, 1,
2, ...,
> 9) and IsNull will be false for all bars (since it is on the last
> symbol, which does not have any nulls). You will have set Count for
> all bars as follows:
>
> Count = 9 - 0;
>
> This is wrong for multiple reasons.
>
> 1. There are 10 symbols, not 9.
> 2. You are overwriting all previous calculations of Count based
only
> on the values of the last symbol. All calculations of Count based
on
> the NULL values of the previous symbols have been lost.
>
> Why did you change the code from what you had? The whole thing can
be
> simplified down to:
>
> list = CategoryGetSymbols(categoryGroup, 0);
> count = 0;
>
> for (i = 0; (sym = StrExtract(list, i)) != ""; i++) {
> count += IIf(IsNull(Foreign(sym, "C")), 1, 0);
> }
>
> Plot(count, "Count", colorRed, styleLine | styleThick |
> styleOwnScale);
>
> Mike
>
> --- In amibroker@xxxxxxxxxxxxxxx, "Paolo Cavatore" <pcavatore@>
> wrote:
> >
> > I'm trying to know how many symbols are not empy in my universe
on a
> > bar-by-bar basis...the following code now seems to be working.
> >
> > Thanks for every hint
> >
> > p
> >
> > // EmptySymbols finder
> > // retrive comma-separated list of symbols
> > // from Group 0
> > list = CategoryGetSymbols(categoryGroup, 0);
> >
> > Count = 0;
> >
> > for( i = 0; ( sym = StrExtract( list, i ) ) != ""; i++ )
> > {
> > SetForeign(sym);
> > myforeign = C;
> > RestorePriceArrays();
> >
> > //if the symbol is empty Count is not increased
> > Count = i - IIf(IsNull(myforeign), 1, 0);
> >
> > _TRACE("symbol " + sym);
> > _TRACE("Count " + Count);
> > _TRACE("IsNull " + IsNull(myforeign));
> >
> > }
> >
> > Plot(Count, "Count", colorRed, styleLine | styleThick);
> >
> > --- In amibroker@xxxxxxxxxxxxxxx, "Mike" <sfclimbers@> wrote:
> > >
> > > Your code is working fine. What is it that you are trying to do?
> > >
> > > As written, your code is counting (on a bar by bar basis since
you
> > are
> > > working with arrays) the number of symbols that have a Null
value
> > for
> > > a Close.
> > >
> > > Just add a Plot statement for the Count array and scroll back
> > through
> > > time to see that the value will increase as more and more
symbols
> > run
> > > out of data. Be sure that at least 1 symbol in your group
actually
> > > runs out of data before any of the others, or actually does
have a
> > > Null value for Close at some point in its history.
> > >
> > > Mike
> > >
> > > --- In amibroker@xxxxxxxxxxxxxxx, "Paolo Cavatore" <pcavatore@>
> > > wrote:
> > > >
> > > > Having changed
> > > > IIf(IsNull(myforeign), Count, Count++);
> > > > into
> > > > Count = Count + IIf(IsNull(myforeign), 1, 0);
> > > > is not working either.
> > > >
> > > > It really seems like IsNull function doesn't return True for
> > empty
> > > > symbols.
> > > >
> > > > New entire code below
> > > >
> > > > // EmptySymbols finder
> > > > // retrive comma-separated list of symbols
> > > > // from Group 0
> > > > list = CategoryGetSymbols(categoryGroup, 0);
> > > >
> > > > Count = 0;
> > > >
> > > > for( i = 0; ( sym = StrExtract( list, i ) ) != ""; i++ )
> > > > {
> > > > SetForeign(sym);
> > > > myforeign = C;
> > > > RestorePriceArrays();
> > > >
> > > > //if the symbol is empty Count is not increased
> > > > Count = Count + IIf(IsNull(myforeign), 1, 0);
> > > >
> > > > _TRACE("symbol " + sym);
> > > > _TRACE("Count " + Count);
> > > > _TRACE("IsNull " + IsNull(myforeign));
> > > >
> > > > }
> > > >
> > > >
> > > > --- In amibroker@xxxxxxxxxxxxxxx, "Mike" <sfclimbers@> wrote:
> > > > >
> > > > > Actually, you are running into a documented side effect of
IIF
> > > > usage.
> > > > >
> > > > > Specifically; the IIF statement always executes BOTH the
true
> > and
> > > > the
> > > > > false branches of the code. So, you will always have your
> > Count++
> > > > code
> > > > > executed regardless of the value of the IsNull expression.
> > > > >
> > > > > Refer to the user guide for details:
> > > > > http://www.amibroker.com/guide/afl/afl_view.php?id=72
> > > > >
> > > > > Mike
> > > > >
> > > > >
> > > > > --- In amibroker@xxxxxxxxxxxxxxx, "Paolo Cavatore"
> <pcavatore@>
> > > > > wrote:
> > > > > >
> > > > > > Does anyone know how to skip empty symbols when looping
> > through
> > > a
> > > > > > list of them?
> > > > > >
> > > > > > The code below shows that IsNull function doesn't return
> TRUE
> > > for
> > > > > > empty symbols.
> > > > > >
> > > > > > Thanks,
> > > > > >
> > > > > > paolo
> > > > > >
> > > > > > // EmptySymbols finder
> > > > > > // retrive comma-separated list of symbols
> > > > > > // from Group 0
> > > > > > list = CategoryGetSymbols(categoryGroup, 0);
> > > > > >
> > > > > > Count = 0;
> > > > > >
> > > > > > for( i = 0; ( sym = StrExtract( list, i ) ) != "";
i++ )
> > > > > > {
> > > > > > SetForeign(sym);
> > > > > > myforeign = C;
> > > > > > RestorePriceArrays();
> > > > > >
> > > > > > //if the symbol is empty Count is not increased
> > > > > > IIf(IsNull(myforeign), Count, Count++);
> > > > > > _TRACE("symbol " + sym);
> > > > > > _TRACE("Count " + Count);
> > > > > > _TRACE("IsNull " + IsNull(myforeign));
> > > > > >
> > > > > > }
> > > > > >
> > > > >
> > > >
> > >
> >
>
------------------------------------
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