[FieldTrip] warning: the trial definition in the configuration is inconsistent with the actual data

[Eelke Spaak]

Dear Dieter,

You have correctly tracked down the cause of the warning: the actual
data is inconsistent with a trl-matrix found somewhere in your
data.cfg (.previous) tree.

The reason you are getting these warnings is that certain FieldTrip
functions (apparently including ft_topoplotER and/or some of its
dependencies) require a data.sampleinfo field in your data structure
that is consistent with the actual data. In general, data.sampleinfo
is an Nx2 matrix containing, for each trial in the data, the indices
of the begin and end sample of that trial, with respect to the
original data set (on disk). If such a consistent data.sampleinfo does
not exist, as is the case with your data, fieldtrip will simply
reconstruct this sampleinfo by using 1 as the begin sample of trial 1,
and k as its end sample, where k is the number of samples in trial 1.
Trial 2 will be numbered from k+1 to k+n, where n is trial 2's length,
etc. This allows all FT functions depending on sampleinfo to function
adequately. Thus, given that you understand where the warning comes
from (as is the case), you should not worry about it and can safely
ignore it.

Do keep in mind, though (also for other people on the list, who might
find this post in the future), that you cannot interpret the
reconstructed sampleinfo in terms of the original recording anymore.
This is not an issue with the plotting functions (since you do not
directly use the manipulated data anyway), but might become relevant
when you e.g. use ft_databrowser or ft_artifact_zvalue, which can
return segments of interest in your data, specified in begin and end
samples.

Best,
Eelke

On 28 March 2012 11:26, Dieter Devlaminck <dieter.devlaminck at inria.fr> wrote:
> Dear All,
>
> When I try to invoke the 'ft_topoplotER(cfg,GA_FC)' command, I get the
> following warning
>
> Warning: the trial definition in the configuration is inconsistent with the
> actual data
>
> This happens both with the tutorial data as with my own data and is
> apparently caused by the fact that in the data structure there is a field
> 'previous' which in turn contains a field 'trl' which contains information
> on all triggers found in my original data. As I only take the average of the
> trials corresponding to certain target stimuli with ft_timelockanalysis
> (using 'cfg.trials = find(data.cfg.trl(:,end));') and then try to make a
> plot of that, fieldtrip finds an inconsistency in the dimensions and then
> does some kind of reconstruction, stating the following
>
> Warning: reconstructing sampleinfo by assuming that the trials are
> consecutive segments of a continuous recording
>
> This worries me a bit as I do not know exactly what it is doing although the
> tutorial plot seemed to be the same as the one on the website. What can I do
> to avoid this warning?
>
> I use fieldtrip version 20120308 and matlab R2010b on fedora 14.
>
> Thanks in advance,
> Best regards,
> Dieter Devlaminck
>
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