[Eeglablist] Unequal group size and STUDY use

[arno delorme]

Dear Michael and Hamish,

thanks for reporting the problem. This issue arises due to the  
complexity of the scheme implemented to handle scalp map plotting in  
the case of subject with different number of channels. This scheme was  
currently enforcing to have groups of the same size. To fix this  
problem, I have decided to enforce interpolation so that all subject  
will need to have the same number of channels (or at least subset of  
channels when plotting scalp maps). Scalp maps where the different  
channels average different numbers of subjects do not make much sense  
anyway. There has also been at least two people reporting plotting  
problems after interpolating data, although I have not yet myself been  
able to reproduce the problem. I hope the current fix will solve this  
problem too.

I have reprogrammed the attached std_erpplot.m function so that it can  
handle groups of different sizes (although be sure to interpolate  
missing channels). Please let me know if this fixes your problems  
(just replace this function in the eeglabxxx/functions/studyfunc/  
folder) and it will be integrated in the EEGLAB monthly release. This  
message was forwarded to the list because it is of global interest and  
also because it depicts a problem that is a major current limitation  
for most users. In general though, please use the Bugzilla database  
for reporting problems.

Best,

Arno

ps: For interpolation, there is currently a non-documented bug: if you  
interpolate channels when pre-computing ERPs and then go back to the  
pre-compute GUI to compute ERSP without interpolation, the function  
will crash. This is because all measure have to be consistent in terms  
of interpolation. As described above, the future function will enforce  
interpolation (which is relatively fast). In case the function crashed  
for you, erase all measure data files (*.daterp, *.datersp, *.datspec,  
*.datitc), and type on the command line STUDY.changrp = []; then call  
back the pre-computing interface.

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