concatenate structs and then plot a specified column

I have the following folder, named Dati_Finali:

Each mat file contains a single variable named dati_finali, see the following figure, with different number of rows but equal number of columns:

I would like to concatenate all the dati_finali cells vertically and then plot a specified column.

How can I do this? Thanks

Answer 1

[Adam Danz]

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.

[Gaetano Pavone]

Can you plot the entire code starting from dir() please?

[Adam Danz]

No.

But you can get it started and I'd be happy to help you do your work when you get stuck.

You only need to know 2 or 3 tools: dir, load, and plot. Loading the variables and the vertical concatenation is already shown in my answer.

You can quickly read through the documentation and look at examples.

https://www.mathworks.com/help/matlab/ref/dir.html

[Gaetano Pavone]

I have followed your suggestion and I have tried to implement the code only for the mat files. However I would like to delete the first row of the matrices taht will be concatenated. How can I do this? This is my code

clc
clear all

file = dir();
C = []; 
for i=3:4
    vars = load(file(i).name,'dati_finali')
    C = [C;vars.dati_finali];
end

[Adam Danz]

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]

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]

"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.