Loading multiple mat files and plot them right

I want to plot 3 different .mat files. My Structure looks something like this.

d = dir('*.mat');                   
Anzmat = length(d);                
for j = 1:3         %just use the first 3 Files in the Order structure ->test 1, test 2, test 3
    load(d(j).name)
    
    %%%%%%%Calculations%%%%%%%
    figure();
    plot(t_LP, x_ac)
    title('acceleration shorten file x-axis')
    xlabel('time (s)')
    ylabel('a (m/s^2)')
    %%%%%%%Calculations%%%%%%%
    figure();
    plot(t_LP, y_ac)
    title('acceleration shorten file y-axis')
    xlabel('time (s)')
    ylabel('a (m/s^2)')
    %%%%%%%Calculations%%%%%%%
    figure();
    plot(t_LP, velocity_x)
    title('velocity shorten file x-axis')
    xlabel('time (s)')
    ylabel('v (m/s)')
    %%%%%%%Calculations%%%%%%%
    figure();
    plot(t_LP, velocity_y)
    title('velocity shorten file y-axis')
    xlabel('time (s)')
    ylabel('v (m/s)')
    %%%%%%%Calculations%%%%%%%
    plot(t_LP,ac,'r')
    title('final velocity')
    xlabel('time (s)')
    ylabel('v (m/s)')
end

Now my aim is to plot the Files: test 1, test 2, test 3 together in one diagramm. So in the end i should have 5 plots and in each are 3 diagramms from the test1,test2,test3 mat data. So i can clearly analyse how different the measurements are in one plot.

[Daniel Basow]

I dont know if its a good solution but my idea is to make following.

At the end of the code i define my ac, t_LP with the numbers from the file. In the outside the For Loop i have all my files seperatly defined an can plot them without any problems.

d = dir('*.mat');                   
Anzmat = length(d);                
for j = 1:3         %just use the first 3 Files in the Order structure ->test 1, test 2, test 3
    load(d(j).name)
    
%%%Calculations%%%%
assignin ('base',['x_ac_' num2str(j)], x_ac);
assignin ('base',['y_ac_' num2str(j)], y_ac);
assignin ('base',['t_LP_' num2str(j)], t_LP);
assignin ('base',['velocity_x_' num2str(j)], velocity_x_);
assignin ('base',['velocity_y_' num2str(j)], velocity_y_);
assignin ('base',['ac_' num2str(j)], ac);
end

hold on
plot(t_LP_1,x_ac_1)
plot(t_LP_2,x_ac_2)
plot(t_LP_3,x_ac_3)
hold off 
.....
    

Does it have a better option to do this?

[Mathieu NOE]

hmm

there are a few answers / posts about why one should avoid dynamic variable names (and therefore not use assignin)

TUTORIAL: Why Variables Should Not Be Named Dynamically (eval) - MATLAB Answers - MATLAB Central (mathworks.com)

Dynamic variable names for full workspace operations - MATLAB Answers - MATLAB Central (mathworks.com)

Answer 1

[Mathieu NOE]

hello

based on the first post you can do that : tested with dummy data ( commented lines) of different size ... so it works whatever the size of each individual file , assumed the same variable names are present in all files :

%% dummy data

% clc
% clearvars
% 
% N = 10;
% t_LP = (1:N);
% x_ac = 1*ones(size(t_LP));
% y_ac = 0.1*t_LP;
% velocity_x = 1*randn(size(t_LP));
% velocity_y = 1*sin(t_LP);
% ac = x_ac + y_ac;
% save test1.mat t_LP x_ac y_ac velocity_x  velocity_y ac
% 
% N = 20;
% t_LP = (1:N);
% x_ac = 2*ones(size(t_LP));
% y_ac = 0.2*t_LP;
% velocity_x = 1*randn(size(t_LP));
% velocity_y = 1.5*sin(t_LP);
% ac = x_ac + y_ac;
% save test2.mat t_LP x_ac y_ac velocity_x  velocity_y ac
% 
% 
% N = 30;
% t_LP = (1:N);
% x_ac = 3*ones(size(t_LP));
% y_ac = 0.3*t_LP;
% velocity_x = 1*randn(size(t_LP));
% velocity_y = 2*sin(t_LP);
% ac = x_ac + y_ac;
% save test3.mat t_LP x_ac y_ac velocity_x  velocity_y ac

clc
clearvars

d = dir('test*.mat');                   
Anzmat = length(d);                
for j = 1:3         %just use the first 3 Files in the Order structure ->test 1, test 2, test 3
    filename = d(j).name;
    load(filename)
    legend_string{j} = filename(1:length(filename)-4); % filename without the .mat extension
    
    %%%%%%%Calculations%%%%%%%
    figure(1);hold on
    plot(t_LP, x_ac)
    title('acceleration shorten file x-axis')
    xlabel('time (s)')
    ylabel('a (m/s^2)')
    legend(legend_string);
    %%%%%%%Calculations%%%%%%%
    figure(2);hold on
    plot(t_LP, y_ac)
    title('acceleration shorten file y-axis')
    xlabel('time (s)')
    ylabel('a (m/s^2)')
    legend(legend_string);
    %%%%%%%Calculations%%%%%%%
    figure(3);hold on
    plot(t_LP, velocity_x)
    title('velocity shorten file x-axis')
    xlabel('time (s)')
    ylabel('v (m/s)')
    legend(legend_string);
    %%%%%%%Calculations%%%%%%%
    figure(4);hold on
    plot(t_LP, velocity_y)
    title('velocity shorten file y-axis')
    xlabel('time (s)')
    ylabel('v (m/s)')
    legend(legend_string);
    %%%%%%%Calculations%%%%%%%
    figure(5);hold on
    plot(t_LP,ac);
    title('final velocity')
    xlabel('time (s)')
    ylabel('v (m/s)')
    legend(legend_string);
end