ArrayCollection fast filtering

1
votes

I have the following situation: have a screen with 4 charts, each being populated with 59 array collections. Each array collection has 2000+ data points.

This construct needs to be filtered(by time), but the problem I'm encountering is the fact that it takes a long time for the filtering to finish(which is to expected given the amount of data points that need to filtered).

Filtering one chart at a time is not option, so I wanted to ask you what do you think would be the best approach? (should I use vector instead?). To generalize this question what would be the best way to filter large collections in flex/as3?

Thanks.

4
apache-flexactionscript-3
as far as i know Vector is the best option - www0z0k
Vectors don't have built in filtering. There is no "VectorCollection". However, you may be able to write your own Vector filter. Vectors are supposedly significantly faster than arrays. You may want to reconsider your architecture; as that is a lot of collections and a lot of data points. - JeffryHouser
Changing the architecture is really not an option... - Radu
Maybe you just need to optimize more. You didn't post your data model or what you are filtering on. No matter what you do your filters are going to take awhile with all that data. - The_asMan

4 Answers

1
votes

You'll have to squeeze out every bit of performance improvement that's possible and that's suited:

  • use Vector if possible, and as much as you can. It has (contrary to what www.flextras.com posits) a filter property which accepts a filtering function. ArrayCollections are slow. (In general all flex native classes are unnecessarily slow) So if you really HAVE to use ArrayCollections, only use them to present the resulting Vectors.

  • if the problem is that the application "freezes" you can look into green threading so you can present the user with a progress bar, that way they at least have a sense of progress. http://blog.generalrelativity.org/actionscript-30/green-threads/

0
votes

I would suggest to filter large collections on the server. This has several benefits:

  • you may be able to minimize network traffic because only the filtered data have to be transferred
  • server side computing can be parallelized and is typically faster, because of more performant hardware and the server's runtime language (e.g. Java).
  • services requests are done asynchronously, so your client application is not blocked
0
votes

Use vector's wherever possible, use green threading if you still can't manage. Internally we use a lot of dictionaries to cache computed queries for later lookup. Dictionaries in as3 are one of the fastest objects around. So we pre-filter in the background and story the various filterted collections in a dictionary. Not sure if it works for your case.

0
votes

Ok, so I googled around more for green threading and stumbled upon a project by gskinner (PerformanceTestv2). Testing the generation of data vs rendering time got me the following results:

[MethodTest name='Set gain series test: ' time=1056.0 min=1056 max=1056 deviation=0.000 memory=688] //filtering data source

[MethodTest name='Set gain series test: ' time=24810.0 min=24810 max=24810 deviation=0.000 memory=16488] //filtering + rendering.

Next I looked on how to improve rendering time of the chart, but not much improvement. However I did find a project based on Degrafa: Axis. This has been ported to flex 4, event 4.5([Axiss 4.5])3. I've integrated charts based on this framework and the results are really great so far.