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Geary,
Okay, the reason you had to add the extra -1 to the startBar and
endBar formulas is because you didn't put it after the Cum(1) like I did.
With regard to the EOD data, I didn't explain that fully. To test the
line drawing with EOD data using changes in month rather than day, I
had to also change the definition of "xx" to detect different months
rather than different days. That was just for my testing though. With
your formula, you won't see anything on a daily or longer time frame
because it only draws the line across one day, which on a daily chart
is within a single bar (ie. the start and end bars are the same bar).
Drawing parallel trendlines is easy, you just offset the start and end
'y' values by the same amount (for a linear display). The trickier
part though, assuming I understand what you want, is finding the high
and low points to draw them through. If you just want them from the
high and low of yesterday's first bar, then that's easy, but you may
then get other bars cutting through the lines. If you want them
touching a bar but no other bars cutting through (ie. like a tangent),
then that's more difficult if the channel is sloping, as the touch
points may not be the same as the absolute highest and lowest values
during the period (eg. in a down-sloping channel, the high point that
touches the line may actually have a lower 'y' value than an earlier
bar that doesn't touch the line).
Regards,
GP
--- In amibroker@xxxxxxxxxxxxxxx, "Geary" <convertah@xxx> wrote:
>
> GP,
>
> This is the code that I am using:
>
> x = Cum(1);
>
> xx = DateNum() !=Ref(DateNum(),-1);
>
> startbar = LastValue(ValueWhen(xx, x, 2)-1); // Yesterday's start bar
> endBar = LastValue(ValueWhen(xx, x, 1)-2); // Bar before today's start
> bar
>
> ocAvg = (O+C)/2;
> startOc = ocAvg[startBar];
> endOc = ocAvg[endBar];
>
> trendLine = LineArray(startBar, startOc, endBar, endOc,3);
>
> Plot( Close, "Price", colorBlue, styleCandle );
> Plot( trendline, "Trendline", colorRed );
>
> The trendline works just as I wanted but when you mentioned EOD data I
> took a look at daily thru monthly charts and the trendline does not plot
> at all, intraday data plots just fine, so I'm a bit mystified.
>
> I use the trendline as a current day filter so I use it extended.
> The next step is to try and produce two more parallel trendlines that
> will be placed at the high and low of yesterday, yielding a regression
> channel that yields additional filtering.
>
> Your help, and AmiBroker has allowed me to begin to analyze and follow
> the patterns that I see in the market. Up till now I have seen these
> repeating patterns as only, after the fact and too late to act upon. Now
> I believe I will be able to detect them as they evolve and grow.
>
> Once again thank you,
> Best regards
>
> Geary
>
>
> --- In amibroker@xxxxxxxxxxxxxxx, "sumangalam" <sumangalam@> wrote:
> >
> > GP,
> >
> > I can not stop myself from expressing my gratitude : your code helped
> > me in being introduced to the power of Amibroker arrays :
> >
> > > > ocAvg = (O+C)/2;
> > > > startOc = ocAvg[startBar];
> > > > endOc = ocAvg[endBar];
> >
> > With Regards
> >
> > Sanjiv Bansal
> >
> >
> >
> >
> > --- In amibroker@xxxxxxxxxxxxxxx, "gp_sydney" gp.investment@
> > wrote:
> > >
> > > Geary,
> > >
> > > Did you use "Cum(1)-1" for 'x' or just "Cum(1)"?
> > >
> > > Both the LineArray function and manual line formula work fine for me
> > > (although I only have EOD data so have to test it with months rather
> > > than days).
> > >
> > > One oversight with the manual line formula though is that it extends
> > > across the whole chart. To limit it to just between the start and
> > end
> > > bars, mask it like this:
> > >
> > > mask = x >= startBar && x <= endBar;
> > > trendLine = IIf(mask, slope*(x-startBar)+startOc, Null);
> > >
> > > Regards,
> > > GP
> > >
> > >
> > > --- In amibroker@xxxxxxxxxxxxxxx, "Geary" <convertah@> wrote:
> > > >
> > > > GP,
> > > >
> > > > Thank you for taking the time to help me with the auto trendline
> > code I
> > > > greatly appreciate it.
> > > > When I first tried your original code for the start and end bars:
> > > >
> > > > startbar = LastValue(ValueWhen(xx, x, 2)); // Yesterday's
> > start bar
> > > > -original
> > > > endBar = LastValue(ValueWhen(xx, x, 1))-1; // Bar before
> > today's start
> > > > bar -original
> > > >
> > > > It gave me a trendline through the (o+c)/2 of yesterdays second
> > bar and
> > > > todays first bar and it was consistent
> > > > with every stock I tried. I finally came up with a modified
> > version that
> > > > produced a trendline through the (o+c)/2
> > > > of yesterdays first and last bar that works with every stock:
> > > >
> > > > startbar = LastValue(ValueWhen(xx, x, 2)-1); // Yesterday's
> > start bar
> > > > -modified
> > > > endBar = LastValue(ValueWhen(xx, x, 1))-2; // Bar before
> > today's
> > > > start bar -modified
> > > >
> > > > The modified code only works with the LineArray function as when
> > I use
> > > > the slope formula it
> > > > gives me a small offset from the (o+c)/2.
> > > >
> > > > I still need more work on this array stuff because the light has
> > not
> > > > gone on quite yet.
> > > > Once again I am grateful for the help.
> > > >
> > > > Thank you,
> > > > Kind regards
> > > >
> > > > Geary
> > > >
> > > > --- In amibroker@xxxxxxxxxxxxxxx, "gp_sydney" <gp.investment@>
> > wrote:
> > > > >
> > > > > One issue I can see is that you choose the start and end bars by
> > > > > comparing their 'y' values to startvalue and endvalue1. If
> > there are
> > > > > multiple bars with the same (O+C)/2 value, then the startbar and
> > > > > endbar formula will find the most recent occurrences, not the
> > ones
> > > > > used to obtain startvalue and endvalue1.
> > > > >
> > > > > It seems to me you're going about this backwards. I'd find the
> > bar
> > > > > numbers first and then their values, not the other way around.
> > You
> > > > > already have the start bars marked in the "xx" array, so to get
> > the
> > > > > actual bar numbers (or array indices), just use something like:
> > > > >
> > > > > x = Cum(1)-1; // Can also use BarIndex();
> > > > > xx = DateNum() != Ref(DateNum(),-1);
> > > > > startbar = LastValue(ValueWhen(xx, x, 2)); // Yesterday's start
> > bar
> > > > > endBar = LastValue(ValueWhen(xx, x, 1))-1; // Bar before
> > today's start
> > > > bar
> > > > >
> > > > > The 'y' values are then just:
> > > > >
> > > > > ocAvg = (O+C)/2;
> > > > > startOc = ocAvg[startBar];
> > > > > endOc = ocAvg[endBar];
> > > > >
> > > > > although you should test both bar values for being in the valid
> > range
> > > > > 0 to BarCount-1 first. You can plot the line the fundamental
> > way using
> > > > > the formula:
> > > > >
> > > > > slope = (endOc-startOc)/(endBar-startBar);
> > > > > trendLine = slope*(x-startBar) + startOc;
> > > > >
> > > > > or just use the LineArray function:
> > > > >
> > > > > trendLine = LineArray(startBar, startOc, endBar, endOc);
> > > > >
> > > > > Note that these plots will only look correct with linear price
> > scale,
> > > > > unless the price range is small. If you're using semilog, then
> > the
> > > > > line formula is:
> > > > >
> > > > > slope = log10(endOc/startOc)/(endBar-startBar);
> > > > > trendLine = startOc*(10^(slope*(x-startBar)));
> > > > >
> > > > > Hope this helps, although note that I haven't actually tried
> > any of
> > > > > this code.
> > > > >
> > > > > Regards,
> > > > > GP
> > > > >
> > > > >
> > > > >
> > > > > --- In amibroker@xxxxxxxxxxxxxxx, "convertah" convertah@ wrote:
> > > > > >
> > > > > > Hello and good day,
> > > > > > I have been trying to write a formula that will draw an
> > automatic
> > > > > > trendline through the, (O+C)/2, of the first and last five
> > minute
> > > > > > candles of yesterday. I'm new to AFL and had fun trying to
> > get this
> > > > far,
> > > > > > which was only accomplished by searching mail archives,the
> > users
> > > > guide,
> > > > > > knowledge bases and, even the "new" googlesearch.
> > > > > >
> > > > > > The trendline works perfectly on some stocks but other stocks
> > will
> > > > have
> > > > > > the line through one but not both of the candles; while other
> > stocks
> > > > > > show no connection with the trendline at all.
> > > > > >
> > > > > > Thoughts on how to make this really work would be greatly
> > > > appreciated.
> > > > > >
> > > > > > This is the code:
> > > > > >
> > > > > > x = Cum(1);
> > > > > >
> > > > > > xx = DateNum() !=Ref (DateNum(),-1);
> > > > > >
> > > > > > startvalue = LastValue(ValueWhen( Ref (xx,79),
> > (O+C)/2,1 )); /*
> > > > > > (O+C)/2 of first bar of yesterday */
> > > > > > endvalue1 = LastValue(ValueWhen( Ref (xx,1),
> > (O+C)/2,1 )); /*
> > > > > > (O+C)/2 of last bar of yesterday */
> > > > > >
> > > > > > startbar = LastValue( ValueWhen( (O+C)/2 == startvalue, x,
> > 1 ) );
> > > > > > endbar = LastValue( ValueWhen( (O+C)/2 == endvalue1, x, 1 ) );
> > > > > >
> > > > > > Aa = (endvalue1-startvalue)/(endbar-startbar);
> > > > > > b = startvalue;
> > > > > >
> > > > > > trendline = Aa * ( x - startbar ) + b;
> > > > > >
> > > > > > Plot( Close, "Price", colorBlue, styleCandle );
> > > > > > Plot( trendline, "Trendline", colorRed );
> > > > > >
> > > > > > Thank you,
> > > > > > Kind regards
> > > > > >
> > > > > > Geary
> > > > > >
> > > > >
> > > >
> > >
> >
>
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