[FieldTrip] ft_appenddata issue - "cannot append this data"

[Schoffelen, J.M. (Jan Mathijs)]

Hi Thilan,

Have you checked the code? The section in ft_appenddata between line 128-136 should give you pointers to what is going on.

My conclusion would be that the condition on line 131 is not met - specifically  isequaltime=False - which causes the error.

I need to check the equality of the ’time’ field for the LFP_proc_ftdata and EEG_proc_ftdata variables. If this field numerically non-identical, the data cannot be appended.

Good luck,

Jan-Mathijs


On 22 Mar 2023, at 22:11, Thilan Tudor via fieldtrip <fieldtrip at science.ru.nl<mailto:fieldtrip at science.ru.nl>> wrote:

Hi,

Thanks in advance for the help.

I am trying to use ft_appenddata to merge EEG and iEEG (LFP) data as input to run connectivity analysis with ft_connectivity (after processing this merged data with ft_freqanalysis).

EEG data has the following channels: 'F3', 'C3', 'A2', 'O1', 'F4', 'A1', 'C4', 'O2'
LFP data has the following channels: 'LFP1-LFP2', 'LFP2-LFP3'

For my same-subject data, I have the following (output from ft_preprocessing):

LFP_proc_ftdata =

  struct with fields:

     trialinfo: [1332×1 double]
       fsample: 100
    sampleinfo: [1332×2 double]
         trial: {1×1332 cell}
          time: {1×1332 cell}
         label: {2×1 cell}
           cfg: [1×1 struct]

 EEG_proc_ftdata =

  struct with fields:

     trialinfo: [1332×1 double]
       fsample: 100
    sampleinfo: [1332×2 double]
         trial: {1×1332 cell}
          time: {1×1332 cell}
         label: {8×1 cell}
           cfg: [1×1 struct]


I get the following error when I run

cfg = [];
data_merged = ft_appenddata(cfg, proc_ftdata, LFP_proc_ftdata);

Warning: the data has overlapping segments or originates from different recordings on disk
Warning: please consider specifying cfg.keepsampleinfo='no'
Error using ft_appenddata
cannot append this data

Even when I specify cfg.keepsampleinfo='no', I still get "cannot append this data". Is the issue is that there are no common channels between the datasets to run ft_appenddata?


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