Draw Extended Line Indicator

[Trade1953]

Hi,
Is there any way to write an indicator that will draw and extended line between 2 points (say the Close[28] and Close[0] and capture the value of that line for a future bar condition?
I want to use it in a strategy I've written. For instance, lets say I need an extended line drawn between the Close at 14:15 EST yesterday and the Close at 08:00 EST this morning. (I can draw this line in the Strategy, but there are no values to it.)
Once the line is drawn, it stays put. I need to be able to access the value of that line sometime in the future. For instance, If Time > 09:30 EST and Close[0] < Extended line value then Enter Short.

I'm terrible building indicators and have been through all the tutorials but can't find any example that's close. DrawExtendedLine is a drawing command and not an indicator so I can't even open it up to see how it's done.

Suggestion, Help, Guidance, Advice??
Thanks much,
Joe

[NinjaTrader_Austin]

Trade1953, this is possible, but not without a bit of coding. You will basically have to draw the line and then reference the points of the line to run some calculations. The form of a line is y = mx + b, where y is price, m is the slope (change in price over change in bars), and b is the initial offset. For the first point of the line, the change in bars is 0, so you can find the offset, which is equal to the price.

From there, you can divide the change in price between the two points by the number of bars between the points to get the slope. You can then take the initial offset and for every bar you move over, add the slope (so for 5 bars, and a slope of 2, that would y = 2 * 5 + b). This will give you the price of the line at any point after the initial point.

[Trade1953]

Thanks Austin,
That's taking me back quite a few years to the old algebra days. Now if I can find out how to make an indicator that draws a line between 2 points, I can then do the math part.
There just isn't any good samples in Ninja Help about building complex indicators (or a simple one for drawing a line for that matter).
I'll keep your reply handy and I thank you very much for your detailed answer!
Joe

[NinjaTrader_Austin]

Joe, you can draw a line with the DrawLine() method.

This code will draw a line from 10 bars back to the current bar from a price of 1000 to a price of 1001.

// Draws a dotted lime green line from 10 bars back to the current bar
// with a width of 2 pixels
DrawLine("tag1", false, 10, 1000, 0, 1001, Color.LimeGreen, DashStyle.Dot, 2);

[Trade1953]

Hey Austin,
Yes, I already used that in the strategy and it draws the extended line where I need it. There just isn't a value to work with on the line anywhere and I don't know how to program an indicator that draws an extended line and produces values that the strategy can see. (I had tried to make an Indie that just uses DrawExtendedLine but it didn't work, because I don't know what I'm doing with Indies.)

BUT, it dawned on me while making coffee this morning that I DON'T NEED an indicator for the strategy to fire off of. You gave me the answer, but I didn't see it. My mindset was that I needed an Indicator, but I don't! You put me so close that if it had been a snake it would have bit me!

So, I'll just program my own extended line in the Strategy itself. I know the value of Close X bars ago, and Close Current Bar. With the formula you reminded me of I can calculate the slope and get the line value each bar into the future just as you suggested. I kept thinking I had to program this in an Indicator.

Thank You very, very much!! I hope I can "pay it forward" one day!
Joe

[djkiwi]

Slope formula

Hi guys, thanks for posting on this. I have one further issue I was hoping someone could throw light. Attached is a chart for CL. I am trying to work out the distance in ticks the close of the current bar is away from the upper channel trendline.

I worked out the slope as 0.13513 based on the following:


start Price 104.982
Finish price 107.924
Bars 28

I know that each trendline point increased by 0.13513 but wondering how to calculate the actual trendline value of the current bar based on this data. I want to do something like this:

if uppertrendlinevalue [0] - Close [0] <= 5 * TickSize.

{do something}

I'm assuming it is something like the opening price of 104.982 x 0.13513 x the number of bars elapsed since the start bar to current bar. Not sure how to do it though.



Cheers
DJ

[koganam]

Hi guys, thanks for posting on this. I have one further issue I was hoping someone could throw light. Attached is a chart for CL. I am trying to work out the distance in ticks the close of the current bar is away from the upper channel trendline.

I worked out the slope as 0.13513 based on the following:


start Price 104.982
Finish price 107.924
Bars 28

I know that each trendline point increased by 0.13513 but wondering how to calculate the actual trendline value of the current bar based on this data. I want to do something like this:

if uppertrendlinevalue [0] - Close [0] <= 5 * TickSize.

{do something}

I'm assuming it is something like the opening price of 104.982 x 0.13513 x the number of bars elapsed since the start bar to current bar. Not sure how to do it though.



Cheers
DJ

double TrendLineValueAtCurrentBar = StartBar + slope * (CurrentBar - StartBar);

[Trade1953]

DJ,
Let me know if that doesn't work for you for some reason and I'll send you the code. I have it working perfectly in one of my strats. Should be no problem having it do "something" when it gets within 5 tics of the line.
Joe

[djkiwi]

Trend

Hi guys, thanks for the quick responses. Well, I have spent 4 hours on this and it has me beat so far so Joe would love some some advice or code to view on how to achieve this.

Cheers
DJ

[koganam]

Hi guys, thanks for the quick responses. Well, I have spent 4 hours on this and it has me beat so far so Joe would love some some advice or code to view on how to achieve this.

Cheers
DJ

What could you not get working with the line that I provided, if I may ask?

[djkiwi]

Start Bar

Hi Koganam

Thanks for posting, well I was not sure what to put exactly in the formula.

double TrendLineValueAtCurrentBar = StartBar + slope * (CurrentBar - StartBar);
I'm not sure what the startbar value is. I think that should be the starting price instead of start bar? I think it needs to be starting price+slope * (Current bar less StartBar).

Thanks
DJ

[koganam]

Hi Koganam

Thanks for posting, well I was not sure what to put exactly in the formula.

double TrendLineValueAtCurrentBar = StartBar + slope * (CurrentBar - StartBar);
I'm not sure what the startbar value is. I think that should be the starting price instead of start bar? I think it needs to be starting price+slope * (Current bar less StartBar).

Thanks
DJ

You wrote this:

I worked out the slope as 0.13513 based on the following:


start Price 104.982
Finish price 107.924
Bars 28

I took that as the jumping off point, assuming that you must have recorded the "start Price". You merely need to record the bar number at the "start Price": that would be the StartBar.

Maybe the correct question to ask, is how did you record the "start Price" that you are using? If you posted your code, maybe, we can just correct it?

[djkiwi]

Code Issues

Hi Koganam, good idea let me post some numbers and code. For starters let me explain what I'm trying to achieve as there maybe an easier way. If you look at the chart attached, it shows a channel. So I want to know the top of the current top of the channel line about channel about 856 and bottom is 831 and insert a signal when it gets close. I have no problems doing this for a horizontal line but upward sloping line like this you need to calculate the slope to get the upper points.

Now the data points on the top lines to work out the slope is start price of 813.12 and finish 849.22 (See the first and third dots on the line). If I count the number of bars from the first data point to the second it is 39 bars which gives a slope of 0.23461.

So I have put the following code in ninja which gives a result of 814.41 which makes no sense as it should be about 856 which is the top of the line. I'm obviously doing something seriously wrong somewhere. Any ideas on this one? Thanks. DJ

#region Variables

private double Opening =813.12 ;
private double slope =0.023461 ;
private int StartBar =39 ;

protected override void OnBarUpdate()

double ResistanceValue = Opening + slope * (CurrentBar - StartBar);

{
DrawTextFixed("Uppertrend","Resistance: "+ResistanceValue.ToString("N2"), bPosition,Color.White,textFontMed, Color.Black, Color.Red, 10);

[Trade1953]

DJ,
Here's a doc with my code in it and some explanation. Now that I see what your are trying to do I'll play around a little too. My code does all the calculations for you but uses the values of a Bar (open, high, low, close) to get the 2 points to draw a trend line. It then calculates the value of the trend line as each bar closes. Don't know if it's what you need but It still might give you some ideas.
Joe

[Baruch]

Hi,
What is the difference btw. DrawLine and DrawExtendedLine?