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[amibroker] Re: Median and its Frequency



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Here's a function that I think will do what you want. I haven't tried
it though, so there could be mistakes.

function MedianCount(data, period)
{
    medo = Median(data, period);
    medCnt = 0;
    for (i = 0; i < BarCount; i++)
    {
        cnt = period;
        for (j = i; j >= 0 && cnt > 0; j--, cnt--)
        {
            if (data[j] == medo[i])
                medCnt[i]++;
        }
    }
    return medCnt;
}

If you only want to include periods with the full "period" bars, start
the 'i' loop at "period" rather than zero. The "j >= 0" part of the
inner loop could then be dispensed with as well.

GP


--- In amibroker@xxxxxxxxxxxxxxx, "meenhal" <meenhal@xxx> wrote:
>
> 
> Your kind attention to detail must be gratefully admired 
> 
> 
> I used the following code 
> 
> 
> medo = Median(C,65);
> 
> medoo [0] = medo;
> for( i = 1; i < 65; i++ ) 
> { medoo[ i ] = medo; } 
> 
> freq=0;
> 
> for( i = 1; i < 65; i++ ) 
> { if ( C[i] == medoo[ i ] )
> 
>    freq= freq+1 ; )
> 
> First loop was an attempt to populate an array with the value of 
> median so that then the array [c] could be compared with it. Well it 
> did not work. The only option left is to actually find the numerical 
> value of the median for each ticker in the first instance and then 
> mechanically plug in that number in the second loop to find the 
> frequency. This seems to be the dumbest way of programming. I am 
> sure there must be a better way. 
> 
> More help please
> Ta
> 
> 
> 
>  
> 
> --- In amibroker@xxxxxxxxxxxxxxx, "gp_sydney" <gp.investment@> 
> wrote:
> >
> > Firstly, loops should go from zero to last-1 rather than one to 
> last.
> The first FOR loop was to populate a dummy array with > Also, if 
> you're going to use an absolute value for the limit (ie. the
> > 260 in your example) then you need to add checking for that being 
> out
> > of range of the current chart. Arrays are only dimensioned up to
> > BarCount, whatever that is for the current chart, so if BarCount is
> > less than 260 in this case you'll have a problem.
> > 
> > Finally, I don't think that logic will give you what you want. That
> > just checks, for each bar, if that bar is the same as the median of
> > the last 260 days and then adds them up, which is what I mentioned
> > before. I gather you want a value at each bar of the number of 
> bars in
> > the last interval that match the median over the same interval. I
> > think you'll need nested loops for that, one to go through the 
> bars,
> > and another inside it to count back through the previous interval 
> (eg.
> > 260) number of bars, with appropriate range checking.
> > 
> > Regards,
> > GP
> > 
> > 
> > --- In amibroker@xxxxxxxxxxxxxxx, "meenhal" <meenhal@> wrote:
> > >
> > > Thanks for you help
> > > 
> > > I do not have much of a code....at least not for this segment
> > > 
> > > Median is found using the standard AFL function
> > > 
> > > I can now envisage the following pseudocode
> > > 
> > > medd = median(c,260)
> > > 
> > > for k = 1 to 260
> > >         medo [k] = medd
> > > next
> > > 
> > > freq = 0
> > > for j = 1 to 260          
> > >       if c[i] = medo[i] then feq = freq +1
> > > next
> > > 
> > > addcolumn  frequency
> > > 
> > > Thanks for pointing the = and ==
> > > 
> > > 
> > > --- In amibroker@xxxxxxxxxxxxxxx, "gp_sydney" <gp.investment@> 
> > > wrote:
> > > >
> > > > > if c [i] = median (close,60)
> > > > 
> > > > That won't work because you're trying to compare a number with 
> an
> > > > array of numbers, plus you need the relational equals operator 
> (==)
> > > > rather than the assignment one (=). Read the median array into 
> a
> > > > variable first and then use indexing on that:
> > > > 
> > > > medc = median(close,60);
> > > > if (c[i] == medc[i])
> > > > 
> > > > However, without seeing the rest of your code, I have a 
> feeling you
> > > > still won't end up with what you're expecting. This is 
> comparing 
> > > the
> > > > current bar's close with the median of the previous 60 bars 
> > > (counting
> > > > the current one), so if you only count those, it will give you 
> a 
> > > count
> > > > of how many bars had a close equal to the median of the last 
> 60 
> > > bars.
> > > > If at each bar you want a count of how many bars in the 
> previous 60
> > > > were the same as the median over that range, then the 
> calculation 
> > > will
> > > > be different, probably involving nested loops.
> > > > 
> > > > GP
> > > > 
> > > > 
> > > > --- In amibroker@xxxxxxxxxxxxxxx, "meenhal" <meenhal@> wrote:
> > > > >
> > > > > To set an entry point, I am trying to find price deviations 
> from 
> > > mean 
> > > > > and median for different intervals.
> > > > > 
> > > > > All is easy except:  I can not determine the frequecy of 
> median 
> > > i.e. 
> > > > > the number of occurences when the price was median during 
> the 
> > > inteval.
> > > > > 
> > > > > median (close,260) will give me the median closing price for 
> 260 
> > > bars 
> > > > > but it does not tell whether this prices occured 10 tims or 
> 88 
> > > times.
> > > > > 
> > > > > I tried to use the for loop with if c [i] = median 
> (close,60) 
> > > but 
> > > > > AFL's handling of arrays does not permit such an attepmt.
> > > > > 
> > > > > Can anyone please help. Thanks in advance
> > > > >
> > > >
> > >
> >
>




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