I'll vouche for ta-lib as well. I used it in an excel trading/chart app I made years ago.
My approach for the ticker data array would be to use a for..loop instead of hard coding. That way you could adjust a few paramaters. When it comes to technical indicators, I prefer making the calcs on the server side and then having the data available to be plotted passed/requested/whatever. The reason being I can use that data in whatever client I want versus trying to learn different ways of doing the same thing in different clients. Another approach you might want to look at is using a charting library that has built in functions for the traditional indicators. I've used ChartDirector from ASE in multiple clients and multiple platforms. http://www.advsofteng.com/ You could write up your charting section in whatever and then bring it into flex as an image. ChartDirector is also open enough that you can program custom indicators into as well which is something I've done quite a few times and is what really sold me on the product. --- In flexcoders@yahoogroups.com, Jake Churchill <reyna...@...> wrote: > > We do the same thing. See this screen shot: > > http://www.reynacho.com/wp-content/uploads/2009/05/cse-charting.jpg > > There's a lot more than just a moving average and bollinger bands there but > those are parts of it. In order to get this data, we first tapped into a > feed which you have to pay good money for. I believe we are using NxCore > which I think is a DTN product. You might look into that but I know there > are others as well. > > For the data, we pass data into a java library called ta-lib: > http://ta-lib.org/ > > It has methods for moving averages, deviations, etc. We found that the > calculations for our app were simply too intense to be done on the client. > But, we have 5-7 years worth of data that we are looking at for calculations > so you might not run into the same bottleneck we had > > -Jake > > On Fri, Oct 23, 2009 at 11:49 AM, cjsteury2 <cra...@...> wrote: > > > > > > > > > > > <answer>.net SQL database through Web services call to Flex...</answer>... > > would like to create a new Array based on existing Array of Ticker data.. > > > > So I need to create a new Array Collection then loop through and add the > > date from the Tickers Array Collection along with the Moving 20 day average > > of the Close Price... THEN ( I have not mentioned this ) What I REALLY want > > is a Standard Deviation Calcuation against the Moving Average to plot Upper > > and Lower Bollinger Bands.... > > > > Here's my initial guesstimate at building the new 20 Day Moving Average > > Array Collection from the Existing Array_Tickers ArrayCollection.... > > > > [Bindable] public var Array_BBands:ArrayCollection; (new mov avg Ac) > > > > public function bld_Array_BBands():void > > { > > Array_BBands = new ArrayCollection; > > for (var i:int=0;i<Array_Tickers.length;i++) \\ loop through existing > > Array_Tickers > > { > > Array_BBands.addItem(Array_Tickers.getItemat(i).date); > > if (i>=20) \\ start at 20th row - as Moving Avg is 20 day > > { > > var mavg_tick:Int = 0; \\ create variable to hold Moving Average > > mvag_tick = Array_Tickers.getItemAt(i).close.valueof(); \\ need to pick up > > the date of the Array_Tickers > > mvag_tick += Array_Tickers.getItemAt(i-1).close.valueof(); > > mvag_tick += Array_Tickers.getItemAt(i-2).close.valueof(); > > mvag_tick += Array_Tickers.getItemAt(i-3).close.valueof(); > > mvag_tick += Array_Tickers.getItemAt(i-4).close.valueof(); > > mvag_tick += Array_Tickers.getItemAt(i-5).close.valueof(); > > mvag_tick += Array_Tickers.getItemAt(i-6).close.valueof(); > > mvag_tick += Array_Tickers.getItemAt(i-7).close.valueof(); > > mvag_tick += Array_Tickers.getItemAt(i-8).close.valueof(); > > mvag_tick += Array_Tickers.getItemAt(i-9).close.valueof(); > > mvag_tick += Array_Tickers.getItemAt(i-10).close.valueof(); > > mvag_tick += Array_Tickers.getItemAt(i-11).close.valueof(); > > mvag_tick += Array_Tickers.getItemAt(i-12).close.valueof(); > > mvag_tick += Array_Tickers.getItemAt(i-13).close.valueof(); > > mvag_tick += Array_Tickers.getItemAt(i-14).close.valueof(); > > mvag_tick += Array_Tickers.getItemAt(i-15).close.valueof(); > > mvag_tick += Array_Tickers.getItemAt(i-16).close.valueof(); > > mvag_tick += Array_Tickers.getItemAt(i-17).close.valueof(); > > mvag_tick += Array_Tickers.getItemAt(i-18).close.valueof(); > > mvag_tick += Array_Tickers.getItemAt(i-19).close.valueof(); > > var mavg:Int = (mavg_tick/20); > > Array_BBands.addItem(mavg); > > } > > } > > > > } > > > > If that works ( and I have no idea if it will ) then I need to get the > > Standard Deviation calcualted somehow. Because the Formula for what I really > > want as previously stated is The Bollinger Bands formular or (MA+K*sigma) > > Moving Average (20 period) + or - depending if it's upper or lower (2 * > > sigma) Sigma is the Standard Deviation, and I am fairly certain that > > actionscript does not calculate the Standard Deviation, so I'll need to do > > that somehow and I have no idea how to do that... > > > > This is a lot for me, and I don't expect you or others have the answers but > > I need to get the Std Deviation caclulated from the Mean Value above and > > this is how to do that... > > > > http://en.wikipedia.org/wiki/Standard_Deviation > > > > I am not sure exactly the best way to proceed, but if anyone has a > > suggestions... I guess I would take the difference of each number in the > > series above form the mean, divide the sum of the numbers by the count (20) > > and take the square root. > > > > It's a brain teaser and I am working on it a piece at a time..... > > > > If anyone has a shortcut I'd take it. > > > > --- In flexcoders@yahoogroups.com <flexcoders%40yahoogroups.com>, > > "jc_bad28" <jc_bad28@> wrote: > > > > > > How are you receiving your price data to plot? Price feed? Static file? > > What you could do is create a function to loop through the array and perform > > the moving average calculation and add the result as an extra "column" in > > the array. Are you plotting the full historic price data set? If so, your MA > > will begin at the nth bar where n is your MA period setting. eg.. a 20 day > > MA won't start until the 20th day into the data set. > > > > > > If you're using a static dataset, you could do the calculation in Excel > > and then save the entire datset as XML and just bring that into flex and > > plot the MA from the existing values. > > > > > > --- In flexcoders@yahoogroups.com <flexcoders%40yahoogroups.com>, > > "cjsteury2" <craigj@> wrote: > > > > > > > > Hi all, > > > > > > > > I am stumped. > > > > > > > > If I want to add an additional data series to a HLOC Chart that is a > > line series of a simple 20 day moving average for the closing price > > ("Close") value in an array collection (Array_Tickers)... how would I > > perform that calculation in Flex? > > > > > > > > <mx:lineSeries id=mavg > > > > dataprovider="Array_Tickers" > > > > ySeries="Close" /> > > > > > > > > How would I calculate "Close" as {The SUM for the Value of "Close" for > > the previous 20 days / divided by 20}... > > > > > > > > > > > > > >
