[FieldTrip] ft_redefinetrial problem

[qi li]

Hi All,

Thanks a lot for your help! The codes look like this

cfg=[];
cfg.trl=trial; %user defined 20*3 matrix
triggered_trials=ft_redefinetrial(cfg,triggered_trials);


 cfg = [];
  cfg.method = 'triangulation';
  cfg.neighbours = ft_neighbourselection(cfg,   triggered_trials);

The error message is 'sen.pnt' not found. I am using 1223 version.

Qi

On Thu, Jan 12, 2012 at 4:09 PM, jan-mathijs schoffelen <
jan.schoffelen at donders.ru.nl> wrote:

> Hi guys,
>
> I agree with Nathan that some additional information would be helpful. The
> 'problem' Qi relates to (at least the issue with the hdr.grad) is a change
> in the way the sensor-array is defined in FT. A while ago we changed the
> .pnt/.ori naming scheme into .chanpos/.coilpos/.coilori to make the
> distinction between channels and coils more transparent. There is a thread
> on this mailing list about it and more documentation can be found on:
>
>
> http://fieldtrip.fcdonders.nl/faq/how_are_electrodes_magnetometers_or_gradiometers_described
>
> In general this change should not affect your analysis, unless you are
> relying on outdated code, or custom-written code which expects the
> .pnt/.ori fields still to be present.
>
> If you want to chop up your data into short fixed length segment, you
> should use ft_redefinetrial with the options: cfg.length and cfg.overlap.
>
> BW,
>
> JM
>
> On Jan 12, 2012, at 10:02 PM, Nathan Weisz wrote:
>
> Hi Qi,
>
> providing some code, including some output may actually help …
>
> I am unaware of ft_redifinetrial altering the contents of your hdr field
> (i admit i have never paid attention to it), but even if it did how does
> this affect your subsequent analysis steps? e.g. at least to my knowledge,
> FT looks for data.grad (instead of data.hdr.grad) e.g. for plotting, source
> analysis etc. so if you add your grad info via ft_read_sens, then
> everything should be fine …
>
> otherwise, if the original hdr content is so important, then save it as a
> temporary variable and add it to your redefined trial later.
>
> but perhaps i have totally misunderstood your problem. in that case see
> introductory remark on code.
>
> good luck,
> n
>
> On 12.01.2012, at 17:20, qi li wrote:
>
> Hi,
>
> I have a fixed length experiment raw. I  apply ft_redefinetrial with
> cfg.trl to epoch it into many segments. When this step is done, the
> output.hdr.grad has different fields from the input field. More
> specifically the pnt and ori field are gone thus cause trouble for the
> later analysis.*  *I am using 12/23 version, is there a bug or it is
> suppose to be so.
>
> If I only want to separate the long data into segments, which command can
> change only the time window while keeping all the other parameters
> unchanged?
>
> Thanks!
>
> Qi
>
>
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>
> _______________________________________________
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>
>
> Jan-Mathijs Schoffelen, MD PhD
>
> Donders Institute for Brain, Cognition and Behaviour,
> Centre for Cognitive Neuroimaging,
> Radboud University Nijmegen, The Netherlands
>
> Max Planck Institute for Psycholinguistics,
> Nijmegen, The Netherlands
>
> J.Schoffelen at donders.ru.nl
> Telephone: +31-24-3614793
>
>
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