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Cannot vertically concatenate tables in for loop

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NMarco
NMarco 2021-2-8
评论： NMarco 2021-2-8
Hello experts,
I have an elementary, yet unsolvable issue for me. I checked other questions, I checked the material on the official site but I cannot solve my problem.
I have a 1x1 structure named "tbl" with 17 fields. Each field is a Nx5 table.
I would like to take each table and append that table to the previous one to obtain an Nx5 table, where N is the total number of rows from all the tables.
To append one to the other I know I can do this:
total = [tbl.ID2; tbl.ID4];
But I'd rather do it in a for loop, since I'll add further IDs and it's going to be quite time consuming.
resulting_tbl = table;
for id = tbl
resulting_tbl = [id;];
end
this code above is just creating the same initial structure instead of a new resulting table.
I know I'm missing some basic notions, but I cannot overtake this problem.
Thank you all for your time and help!
Marco
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Stephen23
Stephen23 2021-2-8
@Marco Ninghetto: having lots of numbered fields is not very good data design. It would be better to use a non-scalar structure or even just a simple cell array.
NMarco
NMarco 2021-2-8
@Stephen Cobeldick, so I will probably change the names. I used them as they are because it's easier to trace back to which participant belongs that specific table.

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采纳的回答

Walter Roberson
Walter Roberson 2021-2-8
temp = struct2cell(tbl);
resulting_tbl = vertcat(temp{:});
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Walter Roberson
Walter Roberson 2021-2-8
The image you posted showed all tables as having different heights but all of them had 5 variables. Are there non-empty entries that have a different number of variables?
temp = struct2cell(tbl);
wids = cellfun(@(C) size(C,2), temp);
[uwids, ~, uidx] = unique(wids);
counts = accumarray(uidx(:), 1);
[~, maxidx] = max(counts);
report_table = [counts, uwids];
report_table(maxidx,:) = [];
if isempty(report_table)
fprintf('Congrats! All cells have %d variables!\n', uwids(1));
else
fprintf('Opps! Not all cells have the same number of variables! Uncommon ones:\n');
fprintf('%d cells have %d variables\n', report_table.');
end
NMarco
NMarco 2021-2-8
Well, my bad. In the fifth column (should be group variable), some of the tables have a different format from the others. That's why it wasn't working. I fixed it.
The method:
temp = struct2cell(tbl);
resulting_tbl = vertcat(temp{:});
worked perfectly. Thanks!

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