[Eeglablist] match electrodes when loading channel location file

[Jerry Zhu]

Hi all,

My head model/channel location files (.sfp files) have the order of
electrodes like this:
FidNz     0     9.071585155     -2.359754454
FidT9     -6.711765     0.040402876     -3.251600355
FidT10     6.711765     0.040402876     -3.251600355
E1     5.787677636     5.520863216     -2.577468644
E2     5.291804727     6.709097557     0.307434896
E3     3.864122447     7.63424051     3.067770143
E4     2.868837559     7.145708546     4.989564557
E5     1.479340453     5.68662139     6.812878187
….
E127     -3.743504949     6.649204911     -6.530243068
E128     -6.118458137     4.523870113     -4.409174427
Cz     0     0     8.87405
The EEG data only have data for E1, E2, …, E128 (i.e. 128 data channels)
After loading the channel location file, I mark FidNz, FidT9, FidT10, and
Cz as non-data channel.
Seems like the pop_chanedit() can match the channel with its location
correctly regardless there are three fiducial electrodes at the top and Cz
at the bottom in the channel location file

However, if I mess up the channel location file by changing it to (notice
E1 has been moved to after E4):
FidNz     0     9.071585155     -2.359754454
FidT9     -6.711765     0.040402876     -3.251600355
FidT10     6.711765     0.040402876     -3.251600355
E2     5.291804727     6.709097557     0.307434896
E3     3.864122447     7.63424051     3.067770143
E4     2.868837559     7.145708546     4.989564557
E1     5.787677636     5.520863216     -2.577468644
E5     1.479340453     5.68662139     6.812878187
….
E127     -3.743504949     6.649204911     -6.530243068
E128     -6.118458137     4.523870113     -4.409174427
Cz     0     0     8.87405
EEGLAB would then mark the electrodes in the order of E2, E3, E4, E1,
E5,…E128 instead of E1, E2, E3, E4, E5,…E128

I just want to make sure pop_chanedit() can indeed match things correctly
with my normal sfp files (not being messed like in my example). Does anyone
know anything about the details?

Thank you!
Jerry
--
Jian Zhu, M.A.
Brain and Cognitive Sciences
Department of Psychology
Southern Illinois University Carbondale
Web: http://zhupsy.com

We have two halves in the brain: left and right. Nothing is right in the
left. Nothing is left in the right.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://sccn.ucsd.edu/pipermail/eeglablist/attachments/20140621/31dbf1f7/attachment.html>