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<div style="direction: ltr;font-family: Tahoma;color: #000000;font-size: 10pt;"><span style="font-size: 13.3333330154419px;">Hi fieldtrippers,</span>
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<div style="font-size: 13.3333330154419px;">I am stuck combining datasets from MEG sessions (note that I do this after preprocessing each individual dataset). I use ft_appenddata to combine the three datasets, which all have a different amount of trials and
often there is a discrepency in the channels as well. After running the following code the alldata structure contains only the channels which are presents in all inputs, but the grad field (which is in the single datasets) is not in the combined datastructure:</div>
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<div style="font-size: 13.3333330154419px;"><i>cfg=[];</i></div>
<div style="font-size: 13.3333330154419px;"><i>alldata = ft_appenddata(cfg, data{1}, data{2}, data{3})</i></div>
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<div style="font-size: 13.3333330154419px;">If I try to use alldata (w/o .grad), I later run into problems using ft_megplanar when I want to do time-frequency analysis. The error is caused by ft_checkdata:</div>
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<div><i>Error using ft_checkdata (line 527)</i></div>
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<div><i>This function requires MEG data with a 'grad' field</i></div>
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<div style="font-size: 13.3333330154419px;">I already tried solving this by using ft_average_sens:</div>
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<div style="font-size: 13.3333330154419px;"><i>for ii=1:length(data)</i></div>
<div style="font-size: 13.3333330154419px;"><i> sens(ii) = data{ii}.grad;</i></div>
<div style="font-size: 13.3333330154419px;"><i>end</i></div>
<div style="font-size: 13.3333330154419px;"><i>alldata.grad = ft_average_sens(sens);</i></div>
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<div style="font-size: 13.3333330154419px;">However, than I get this error:</div>
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<div style="font-style: italic; font-size: 13.3333330154419px;">Error using ft_average_sens (line 101)</div>
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<div style="font-style: italic; font-size: 13.3333330154419px;">all sensor arrays should have the same sensors for averaging</div>
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<div style="font-size: 13.3333330154419px;">How can I incorporate the grad field while I have different channels in each dataset?</div>
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<div style="font-size: 13.3333330154419px;">Best,</div>
<div style="font-size: 13.3333330154419px;">Mats van Es</div>
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