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Hello,
ValueWhen as most AFL functions returns array. If you want
single scalar you can use loop or lastvalue
If you don't want loop (which is actually correct solution),
you may wrap ValueWhen into LastValue.
RES = LastValue( Valuewhen(L <= LastValue( Valuewhen( index == barindex, diff) ), XM) );
Actually even better solution is to address (index) the array directly:
RES = LastValue( Valuewhen(L <= diff[ barindex ], XM) );
Best regards,
Tomasz Janeczko
amibroker.com
----- Original Message -----
From: "jay_podda" <jay_podda@xxxxxxxxx>
To: <amibroker@xxxxxxxxxxxxxxx>
Sent: Tuesday, January 01, 2008 5:57 PM
Subject: [amibroker] Re: Valuewhen
> Hi!
>
> The problem with Valuewhen is, in its expression I can only compare as
> many array I want to compare only for that array index. For example,
>
> Current barIndex is 5415 and value of array C and Val is 49.5 and 1.5
> respectively. Now suppose previous bar with barIndex 4719 has array L
> value of 47.75, which is lower than C-Val of current bar (49.5-1.5=48)
> . So, I want the value of XM[4719] in my RES array element of
> RES[5415].
>
> I tried something like:
>
> diff = C-Val;
> index = BarIndex();
> RES = Valuewhen(L <= Valuewhen(index == barindex, diff), XM);
>
> I thought that inner valuewhen will be executed first, returning
> constant value 48 for outer valuewhen and it will return correct
> value. But, instead it returns value of XM at barindex 3411 where the
> whole valuewhen expression results in true - that is on that bar L is
> < that bars C-Val.
>
> I know that I can do this with loop, but I want to avoid it if
> possible. If I replace Valuewhen(index == barindex, diff) with
> constant 48, it returns correct value.
>
> So, I don't know if I am expecting ValueWhen to do what it's not able
> to. If not, is there any alternative without loop to achieve the same?
>
>
>
>
> --- In amibroker@xxxxxxxxxxxxxxx, ChrisB <kris45mar@xxx> wrote:
>>
>> Jay
>>
>> OK just substitute your formula for Val...
>>
>> Val = (EMA(C,30))/30; // or whatever you like.
>>
>> If you are trying to set a threshold based on
>>
>> Threshold = Close today - Val;
>>
>> and then looking back in time to when a Low of any preceding bar
> crossed
>> that threshold,
>>
>> you will need Cross function, but ALSO if I understand you correctly
> you
>> will likely also need to look into Looping.
>>
>> Looping still leaves me stumped but have a look at the files section
> for
>> the articles
>> Looping in Amibroker AFL.pdf and
>> AFL Looping.pdf.
>>
>> Then just use Valuewhen to find the XM.
>>
>> Regards
>>
>> ChrisB
>>
>> jay_podda wrote:
>> >
>> > Chris,
>> >
>> > Thanks for replying so fast.
>> >
>> > In my case, Val is not constant, its array just like C. Also, L
> might
>> > not be ref-1, it can be more than 1 bars ago. And I want to know
> value
>> > of XM corrosponding to bar on which L is less than current bar's
> C-
>> > Val.
>> >
>> > Thanks again,
>> > --- In amibroker@xxxxxxxxx ps.com
>> > <mailto:amibroker%40yahoogroups.com>, ChrisB <kris45mar@ ..>
> wrote:
>> > >
>> > > Hi Jay
>> > >
>> > > See if this is what you are looking for:
>> > >
>> > > Val = Param("Val", 1.5 , 1, 3, 0.1);
>> > >
>> > > XM = High;//for argument's sake.
>> > >
>> > > CminusVal = Close - Val;
>> > > Cond1 = Ref(L,-1) < (C-Val);
>> > > myXM= ValueWhen ( Ref(L,-1) < (C -Val),XM);
>> > >
>> > > // run the Exploration to check you values
>> > > Filter = 1;
>> > >
>> > > AddColumn(Val, "Val", 1.2);
>> > > AddColumn( XM,"XM", 1.2);
>> > > AddColumn (C, "close",1.2) ;
>> > > AddColumn(Ref( L,-1),"ref L",1.2);
>> > > AddColumn( CminusVal,"ClessVal ",1.2);
>> > > AddColumn( Cond1, "Cond1", 1.2);
>> > > AddColumn ( myXM, "my XM", 1.2);
>> > >
>> > > // Plot these to visually check
>> > > Plot( myXm,"myXM", colorBlue,1) ;
>> > > Plot( Cond1, "Cond1",colorRed, styleHistogram |styleOwnScale) ;
>> > >
>> > > Regards
>> > >
>> > > ChrisB
>> > >
>> > > jay_podda wrote:
>> > > >
>> > > > I want to find value of array XM when L of very first previous
> bar
>> > is
>> > > > VAL amount less then current bar C.
>> > > >
>> > > > The problem with me is when I use valuewhen, in expression if
> I
>> > use
>> > > > any array for comparision, I can't compare with current bar.
> That
>> > is,
>> > > > if current bar C is 49.50 and VAL is 1.50, I want to get value
> of
>> > XM
>> > > > array when that previous bar's L is less than 48.
>> > > >
>> >
>>
>
>
>
>
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