MATLAB Answers

concatenate structs and then plot a specified column

1 view (last 30 days)
Gaetano Pavone
Gaetano Pavone on 15 Oct 2019
Edited: 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

  0 Comments

Sign in to comment.

Answers (2)

Adam Danz
Adam Danz on 15 Oct 2019
Edited: 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

Show 3 older comments
Adam Danz
Adam Danz on 15 Oct 2019
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
Gaetano Pavone
Gaetano Pavone on 15 Oct 2019
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)))
Adam Danz
Adam Danz on 15 Oct 2019
"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.

Sign in to comment.


Stephen Cobeldick
Stephen Cobeldick on 16 Oct 2019
Edited: 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);

  0 Comments

Sign in to comment.

Products


Release

R2019b

Translated by