Cycling 74 » Topic: Filtering out a flow of numbers http://cycling74.com/forums/topic/filtering-out-a-flow-of-numbers/feed Wed, 19 Jun 2013 20:05:25 +0000 http://bbpress.org/?v=2.2.4 http://cycling74.com/forums/topic/filtering-out-a-flow-of-numbers/#post-57379 <![CDATA[Filtering out a flow of numbers]]> http://cycling74.com/forums/topic/filtering-out-a-flow-of-numbers/#post-57379 Wed, 06 Jul 2011 12:18:59 +0000 ygreq Hi there,

I was using a ultrasonic sensor to control the position of a video. The thing is that the sensor sends a “jitterish” flow of numbers so the image keeps coming back and forth fast.

Does anyone know how I can flatten it so instead of getting for example 197, 198, 196, 197, and so on, to just get like a median of 197, in this case. But I need it in real time so I don’t want to calculate the actual median.

Any ideas?
thank you,
ygreq

]]> http://cycling74.com/forums/topic/filtering-out-a-flow-of-numbers/#post-205610 <![CDATA[Re: Filtering out a flow of numbers]]> http://cycling74.com/forums/topic/filtering-out-a-flow-of-numbers/#post-205610 Wed, 06 Jul 2011 12:26:06 +0000 AudioLemon If you look at the Extras – Examples – Latest you can find a sensor tamer. It might help.

]]> http://cycling74.com/forums/topic/filtering-out-a-flow-of-numbers/#post-205611 <![CDATA[Re: Filtering out a flow of numbers]]> http://cycling74.com/forums/topic/filtering-out-a-flow-of-numbers/#post-205611 Wed, 06 Jul 2011 12:47:46 +0000 n00b_meister Hi
This is a common issue, and the forum is replete with various solutions. You even mentioned one yourself – the [zl median] object; look at the helpfiles for the [zl] group of objects, and search this forum for ‘smoothing’.
If you’re using Arduino, the following code snippet will allow you to average data before it gets to Max:

int samples=10;//sample rate
int inVal;//pin reading
int inPin = 0;//this is your input pin

//place the following inside your loop function, where you are reading the input voltage

for (int i=0; i
{
inVal += analogRead(inPin); //take ten readings and total them
}
inVal /= samples;//divide total by 10 = average

but you can just as easily do this in Max using the [zl] objects – kneel and worship the mighty [zl]!

Brendan

]]> http://cycling74.com/forums/topic/filtering-out-a-flow-of-numbers/#post-205612 <![CDATA[Re: Filtering out a flow of numbers]]> http://cycling74.com/forums/topic/filtering-out-a-flow-of-numbers/#post-205612 Wed, 06 Jul 2011 13:23:51 +0000 ygreq Hey guys,

Thank you for your input!

@grizzle. From what I know Extras is filled with stuff yourself put there, not Max 5 by itself. So may I ask you what is the name of the patch in the extras you have so I can search it on the net!

@n00b_meister. I will have a look on the internet. I didn’t know how exactly to formulate what I was to search for. I’ll try “smoothing” :D. I’ll let you know how that will work out. In relation to medians, I would have to consider a time period and that would mean less fast final output.
I actually use 4 ultrasonic sensors, and I don’t want to meddle into that sketch as I just made it work fast enough with all these 4 sensors. And I am not that good in that language yet :( (here is the thread on arduino forum: http://arduino.cc/forum/index.php/topic,65751.0.html)

I was thinking of an algorithm that would not output if jitters a little but output if it changes a lot (when you actually change the distance the sensor is measuring). But it should still react fast enough! I was thinking more as a [change] object for numbers that jitter a little.

Simply put, [change] doesn’t output if the input numbers do not change, right? What if it would not output if the input numbers do not change more than -20 or +20?

This is the logic! Now how do I do it? And will it work? :)

Thank you once again

]]> http://cycling74.com/forums/topic/filtering-out-a-flow-of-numbers/#post-205613 <![CDATA[Re: Filtering out a flow of numbers]]> http://cycling74.com/forums/topic/filtering-out-a-flow-of-numbers/#post-205613 Wed, 06 Jul 2011 14:09:37 +0000 broc To filter jitter of range X, divide the input by X (integer), use [change] and scale back multiplying with X.

]]> http://cycling74.com/forums/topic/filtering-out-a-flow-of-numbers/#post-205614 <![CDATA[Re: Filtering out a flow of numbers]]> http://cycling74.com/forums/topic/filtering-out-a-flow-of-numbers/#post-205614 Wed, 06 Jul 2011 14:48:21 +0000 ygreq @grizzle. I found the patch you mentioned. I don’t quite understand it, but I surely will try it some more and check results.

@n00b_meister. I checked the forum looking for “smoothing”. Interesting results indeed! I will copy what I found at the end of this post.

@broc. I will try to test your equation as well for sure!

Thank you so much guys!!!!
ygreq

– Pasted Max Patch, click to expand. –
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