Logical Indexing: deleting empty array

Question

Eric 2013-9-24

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/88106-logical-indexing-deleting-empty-array

I have trial names that end with numbers e.g. _1 or _30. The number suffix does not increment by _1, _2, _3 etc because I am only reading a few one minute trials over a thirty minutes of data. If the condition is 30 minutes, then the data from these trials is being stored in a 1x30 structure even though 2-29 is empty because I am only reading in two trials. Without changing the trial name, is there a way that only stores arrays that are populated?

tnum = str2num(fname(jtnum+1:j)); % trial number if there is one 
tnum(~cellfun(@isempty,tnum));%keeps only populated cells, I hope
%fname is the name of the trial which vary in length depending on the trial type e.g. condition_1. 
%tnum is the trial number e.g. 1, 2, etc 
%j is the length of the fname jtnum = j e.g. 14.
%here is how the data is being stored
if dtype{i} == 3% dtype is a signal and i one of many types of signals 
subj.(fname)(tnum).(datanames{i}) = M(:,i); % M is nxm input matrix 
end%dtype

The second tnum is the line where the error occurs:

Therefore, I added a second line of code,

tnum = mat2cell(tnum)

but got an error saying <Matrix indices must be full double>

If I omit the second tnum, then the code works but I end up with something like this

subj.power_(2)
ans =
ana: []
force: []

but

subj.power_(1)
ans =
ana: [1x1 struct]
force: [1x1 struct]

So, it is these empty structures 2-29 that I want to get rid of and end up with a structure of 1xnumber of trials with data. Any suggestion of how to get rid of the empty array is appreciated.

Eric