"Attempt to reference field of non-structure array" when reading in from a text file using spm_read_vols

I have a list of nifti files that I want to read in from a text file rather than inputting every nifti in the script. I'm trying to get the first timepoint for each nifti file. When I try this command, where '10niftis.txt' is my list of niftis,

data = spm_read_vols('10niftis.txt, 1');

I get the error message "Attempt to reference field of non-structure array".

Any ideas? I'm not sure if I can use textread because I only want the first timepoint within each file.

Answer 1

[Walter Roberson]

I do not know about getting the first time point of each file, but you are using spm_read_vols incorrectly. It should be something like:

fid = fopen('10niftis.txt', 'rt');
K = 0;
while true
  this_nifti = fgetl(fid);
  if ~ischar(this_nifti); break; end   %end of file detected
  K = K + 1;
  V{K} = spm_vol(this_nifti);
  data{K} = spm_read_vols(V{K});
end
fclose(fid);

Maybe you can use

data{K} = spm_read_vols(V{K}(1));

to read only the first time-point -- I have not researched the representation of spm volumes.