[FieldTrip] On meaning of numbers in posclusterslabelmat / negclusterslablemat in results of ft_freqstatistics function

[郭策2021220122]

Hi, 


After conduction of cluster based permutation using ft_freqstatistics, a stat variable can be generated, containing two structs, namely poscterlabelmat and negclusterslabelmat. Both are 3-D data containing integers. I wonder the what is the meaning of the integers because they're not 0-or-1. Instead there're integers like 3, 5, 19, etc. How are these numbers determined? Do all non-zero positive integers indicate "this is a statistically significant point (p<=cfg.alpha)"? Are they determined by p-value?
The picture below can be generated with script
    contourf(0:4:999,frex,squeeze(stat.negclusterslabelmat(22,:,101:350)),50,'linecolor','none');
    set(gca,'clim',[-3 3],'xlim',[0 996]);
xlabel('Time (s)'), ylabel('Frequency (Hz)');
(Note that my TF cluster based permutation was conducted with TF data with a sampling rate of 250 and epoch ends [-0.4s 1.4s], so the script was written to draw a "map" of significant negative clusters within [0s 1s] in TF data comparison, of channel No.22 which was Cz. )
As you can see, there are different depths of color because of different values of non-zero positive integers. Should I say this map shows significant negative TF clusters?
 
Furthermore, what are differences between positve clusters and negative clusters? 
For example, if I have 2 variables to be tested, namely TFRwave1 and TFRwave2, does postive clusters generated with
     [stat] = ft_freqstatistics(cfg, TFRwave1, TFRwave2);
equal negative clusters generated with
    [stat] = ft_freqstatistics(cfg, TFRwave2, TFRwave1);
?

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