add method to rereference channels

[Andrey1994]

https://pressrelease.brainproducts.com/referencing/

[IbrahimBagalwa]

https://pressrelease.brainproducts.com/referencing/

Hello @Andrey1994 , I would like to kindly request for further explanation regarding the issue at hand. I am interested in working on this matter and would greatly appreciate it if you could provide more details. Thank you very much for your time and consideration.

[Andrey1994]

Hi and thanks for willing to implement it!

I think method signature should look like this: void reference(BrainFlowArray<double, 2> data, std::vector<int> channels_to_reference, std::vector<int> reference_channels)

That should be done for all supported languages.

In terms of implementation first of all you need to average data from reference_channels and after that subtract the averaged data from channels_to_reference

In BrainFlow in general we implement everything in C\C++ and call methods from dyn libs from other languages, but here since implementation is very simple(just average multiple arrays and subtract) and since it requires 2d arrays I think it's ok to just implement it for each language

[kkashiva]

Hi @Andrey1994, I'm trying to implement this and was reading your comment. The reference method signature and the implementation logic seem helpful.

When you say

That should be done for all supported languages.

As an example for java_package, do we need to add a helper method to the DataFilter.java? (brainflow/java_package/brainflow/src/main/java/brainflow/DataFilter.java)

Or the reference method needs to be added to a separate/different file?

[Andrey1994]

Hi and thanks for working on it!

It should be a static method of DataFilter class for all languages

[kkashiva]

Hi @Andrey1994 The reference method implementation in DataFilter class is ready for review for the java_package in this draft PR #630
I'll work on similar logic to implement this in other languages (Java is my strongest, so I started there).

I just have 1 doubt on where will this method be called from?