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concatenate structs and then plot a specified column

Asked by Gaetano Pavone on 15 Oct 2019
Latest activity Edited by Stephen Cobeldick on 16 Oct 2019
I have the following folder, named Dati_Finali:
folder.JPG
Each mat file contains a single variable named dati_finali, see the following figure, with different number of rows but equal number of columns:
cell.JPG
I would like to concatenate all the dati_finali cells vertically and then plot a specified column.
How can I do this? Thanks

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R2019b

2 Answers

Answer by Adam Danz
on 15 Oct 2019
Edited by Adam Danz
on 15 Oct 2019

Use dir() to list all files in the directory.
Loop through each file and load in the variable using load(filename,variables)
From within your loop you can vertically concatenate like so
C = [];
for i = 1:numberOfFiles
vars = load('filename','dati_finali')
C = [C;vars.dati_finali];
% ^ vertical concatenation
end
Then plot colun number 'n' by
plot(C(:,n))
If you have trouble putting any of this together, feel free to comment below and include the code.

  6 Comments

file=dir() is ok if all of your files are in your current directory. Otherwise, you may want to include the directory path as the first input to dir().
To delete the first row of a matrix, 'M'
m(1,:) = [];
Do you want to delete the first row of every matrix? If so, you can just concatenate starting at row 2 as shown below.
for i=3:4
vars = load(file(i).name,'dati_finali')
C = [C;vars.dati_finali(2:end,:)];
% ^^^^^^^
end
I want to delete the first row of the uploaded matrices, except for the first one. If i use your code all first rows will be eliminated.
Moreover, plot of the 16th column is:
heights=C(:,16);
plot(cell2mat(heights(:,1)))
"I want to delete the first row of the uploaded matrices, except for the first one. "
That's what conditional statements are for.
for i=3:4
vars = load(file(i).name,'dati_finali')
if i==3 % <--3 because your i-loop starts with 3
Cnew = vars.dati_finali;
else
Cnew = vars.dati_finali(2:end,:);
end
C = [C; Cnew];
end
About your cell array, what's stored in that array? Are they all numbers or is there a mix of numbers and strings/characters or other stuff? The solution for plotting the n_th column will depend on what's in those arrays.

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Answer by Stephen Cobeldick on 16 Oct 2019
Edited by Stephen Cobeldick on 16 Oct 2019

Simpler without conditional statements:
D = 'path to the folder/Dati_Finali';
S = dir(fullfile(D,'*.mat'));
b = 1;
for k = 1:numel(S)
T = load(fullfile(D,S(k).name));
S(k).data = T.dati_finali(b:end,:);
b = 2;
end
C = vertcat(S.data);

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