Dot indexing is not supported for variables of this type

The script does create the variable vel. It is a 1x1 struct with data and headers.

Any ideas why the error is still reported? Thanks in advance (script in attachment)

[Matt J]

We cannot run your code (because it is an image).

[Lissa]

startpath = ('/MATLAB Drive/BIOMECHLISSA')
timecolumns = importdata('/MATLAB Drive/BIOMECHLISSA/Timing-IMU-viconNEW.xlsx');
for k = 1:2
    starttimeIMU = timecolumns(k,5) % SUP HR IMU
    starttimeOS = timecolumns(k,6) % SUP HR OPENSIM
    %%%%%%%%%%%%%%%%%%%% PART ONE %%%%%%%%%%%%%%%%%%%%%%%
    %%% IMU %%%
    addpath ('/MATLAB Drive/BIOMECHLISSA/RAW IMU') % IMU data inladen, van Jente gekregen = dit exporteert alle IMU data
    name = sprintf('MATLAB Drive/BIOMECHLISSA/RAW IMU/Sup_HR_Trial0%d_data.mat',k)
    load(name);
    Hinge = sprintf('MATLAB Drive/BIOMECHLISSA/RAW IMU/Sup_HR_Trial0%d_RotAxis_Steer.mat',k)
    load(Hinge)
    xdd = Data.Tibia.AccWorld;
    iFreeAcc = find(strcmp(Data.Tibia.header,'FreeAcc_E')); % bij header kijken wat er allemaal instaat, vrije acceleratie E (maar dus eigenlijk ook N en U denk ik, zie hieronder)
    xdd2 = Data.Tibia.data(:,iFreeAcc:iFreeAcc+2); % ik denk dat die nu FreeAcc_E, FreeAcc_N, FreeAcc_U heeft genomen dus 3 kolommen van data

    % FIGURE 1 DIFFERENCE BETWEEN WITH AND WITHOUT GRAVITY
    figure(1)
    subplot(311); % X AS
    plot(xdd(839:end,1)); hold on;
    plot(xdd2(839:end,1)); hold on; % x as
    xlabel('Time [ms]','FontSize', 8)
    ylabel ('Knee acc [°/ms²]','FontSize', 8)
    title('IMU Acc in x-direction SUP HR T02','FontSize', 8)
    legend('Acc with gravity','Acc without gravity','location','northeast')
    %subplot(312); % Y AS
    plot(xdd(839:end,2)); hold on;
    plot(xdd2(839:end,2)); hold on; % y as
    xlabel('Time [ms]','FontSize', 8)
    ylabel ('Knee acc [°/ms²]','FontSize', 8)
    title('IMU Acc in y-direction SUP HR T02','FontSize', 8)
    legend('Acc with gravity','Acc without gravity','location','northeast')
    %subplot(313); % Z AS
    plot(xdd(839:end,3)); hold on;
    plot(xdd2(839:end,3)); hold on; % z as → probleem: bij de z: been is stil maar versnelling is niet nul want werkt in tegen de zwaartekracht want je houdt been vast - want er is een continue valversnelling, OpenSim houdt hier geen rekening mee dus we willen dit er af trekken - IMU heeft dit ook al gedaan en dat staat onder vrije acceleraties → zie figuur oranje onderste lijn, nu vertrekt die wel mooi vanaf nul omdat er 9.81 is van af getrokken
    xlabel('Time [ms]','FontSize', 8)
    ylabel ('Knee acc [°/ms²]','FontSize', 8)
    title('IMU Acc in z-direction SUP HR T0','FontSize', 8)
    legend('Acc with gravity','Acc without gravity','location','northeast')
    xdd_norm = zeros(length(xdd2),1);
    for f=1:length(xdd2)
        xdd_norm(f) = norm(xdd2(f,:)); % gebruikt NORM FUNCTION (!!) norm(v) returns the Euclidean norm of vector v. This norm is also called the 2-norm, vector magnitude, or Euclidean length.
    end

    % FIGURE 2 IMU VERSNELLING NORM WAARDE
    figure(2)
    plot(xdd_norm(839:end)); hold on; % IMU: dit is dus de versnelling in één waarde weergegeven (frames en pendulumbeweging) → HET IS DIT DAT WE WILLEN VERGELIJKEN MET DE VERSNELLING IN OPENSIM!!
    xlabel('Time [ms]','FontSize', 8)
    ylabel ('Knee acc [°/ms²]','FontSize', 8)
    title('IMU Norm SUP HR T02','FontSize', 8)

    %%% OPENSIM %%%
    %     dataFolder = [startpath '/POINT KINEMATICS/'];
    %     dataFile = fullfile(dataFolder,['3DGaitModel2354-scaled_PointKinematics_IMU_SUP_HR_T'  num2str(k) '_acc.sto'])
    %     pathwayPK_acc = dir(dataFile);
    %     PK_acc = importdata(fullfile(pathwayPK_acc.folder,pathwayPK_acc.name))
    %     PK_acc2 = PK_acc.data(:,2:4)/(10000000000);

    addpath ('/MATLAB Drive/BIOMECHLISSA/POINT KINEMATICS')
    if k == 1
        PK_acc = importdata('3DGaitModel2354-scaled_PointKinematics_IMU_SUP_HR_T1_acc.sto');
    elseif k == 2
        PK_acc = importdata('3DGaitModel2354-scaled_PointKinematics_IMU_SUP_HR_T2_acc.sto');
    elseif k == 3
        PK_acc = importdata('3DGaitModel2354-scaled_PointKinematics_IMU_UP_HR_T3_acc.sto');
    elseif k == 4
        PK_acc = importdata('3DGaitModel2354-scaled_PointKinematics_IMU_SUP_HR_T4_acc.sto');
    elseif k == 5
        PK_acc = importdata('3DGaitModel2354-scaled_PointKinematics_IMU_SUP_HR_T5_acc.sto');
    end

    PK_acc2 = PK_acc.data(:,2:4)/(10000000000);

    % FIGURE 3 OPENSIM POINT KINEMATICS ACCELERATION
    figure(3)
    plot(PK_acc2(1091:end,:)), hold on;
    xlabel('Time [ms]','FontSize', 8)
    ylabel ('Knee acc [°/ms²]','FontSize', 8)
    title('OPENSIM PK Acc SUP HR T02','FontSize', 8)
    legend('State 0','State 1','State 2','location','northwest')
    PK_acc_norm = zeros(length(PK_acc.data),1); % ook weer norm voor bepaald
    for i=1:length(PK_acc.data)
        PK_acc_norm(i) = norm(PK_acc2(i,1:3));  % gebruikt NORM FUNCTION (!!) norm(v) returns the Euclidean norm of vector v. This norm is also called the 2-norm, vector magnitude, or Euclidean length.
    end

    % FIGURE 4 OPENSIM VERSNELLING NORM WAARDE
    figure(4)
    plot(xdd_norm(starttimeOS:end)); hold on
    plot(PK_acc_norm(starttimeIMU:end)); hold on; legend({'IMU acc norm','OpenSim PK acc norm'},'location','best');
    xlabel('Time [ms]','FontSize', 8)
    ylabel ('Knee acc [°/ms²]','FontSize', 8)
    title('Norm acc: IMU acc vs OPENSIM PK acc SUP HR T02','FontSize', 8)

    firstlengthIMU = (length(xdd_norm)) - starttimeIMU
    firstlengthOPENSIM = (length(PK_acc_norm)) - starttimeOS
    % FIGURE 5 CALCULATING DIFFERENCE SCORE OPENSIM AND IMU ACC NORM!! DUS
    % EIGENLIJK FIGUUR 16 VERSCHIL GENOMEN
    figure(5)
    %subplot(5,1,k)
    if firstlengthIMU > firstlengthOPENSIM
        endtime = firstlengthOPENSIM + starttimeIMU
        plot(PK_acc_norm(starttimeOS:end) - xdd_norm(starttimeIMU:endtime)); hold on;
        xlabel('Time [ms]','FontSize', 8)
        ylabel ('Knee acc [°/ms²]','FontSize', 8)
        title(['Difference IMU Norm & OPENSIM PK acc SUP HR T0' num2str(k)],'FontSize', 6)
    else endtime = firstlengthIMU + starttimeOS
        plot(PK_acc_norm(starttimeOS:endtime) - xdd_norm(starttimeIMU:end)); hold on;
        xlabel('Time [ms]','FontSize', 8)
        ylabel ('Knee acc [°/ms²]','FontSize', 8)
        title(['Difference IMU Norm & OPENSIM PK acc SUP HR T0' num2str(k)],'FontSize', 6)
    end

    addpath ('/MATLAB Drive/BIOMECHLISSA/POINT KINEMATICS')
    if k == 1
        PK_vel = importdata('3DGaitModel2354-scaled_PointKinematics_IMU_SUP_HR_T1_vel.sto');
    end
    if  k == 2
        PK_vel = importdata('3DGaitModel2354-scaled_PointKinematics_IMU_SUP_HR_T2_vel.sto');
    end
    if k == 3
        PK_vel = importdata('3DGaitModel2354-scaled_PointKinematics_IMU_SUP_HR_T3_vel.sto');
    end
    if k == 4
        PK_vel = importdata('3DGaitModel2354-scaled_PointKinematics_IMU_SUP_HR_T4_vel.sto');
    end
    if  k == 5
        PK_vel = importdata('3DGaitModel2354-scaled_PointKinematics_IMU_SUP_HR_T5_vel.sto');
    end

    PK_vel_diff       = diff(PK_vel.data(:,2:4))/0.01;
    PK_vel_diff_norm  = zeros(length(PK_vel_diff),1);
    for z=1:length(PK_vel_diff)
        PK_vel_diff_norm(z) = norm(PK_vel_diff(z,:));
    end
    % FIGURE 6 IMU ACC VS OPENSIM PK DERIVATIVE OF VELOCITY
    figure(6)
    plot(xdd_norm(839:end)); hold on
    plot(PK_vel_diff_norm(1091:end)); hold on; %DIT IS OPENSIM
    legend({'IMU acc norm','OPENSIM vel diff norm'}, 'Location', "best")
    title(['Norm acc: IMU acc vs OPENSIM PK derivative of velocity SUP HR T0' num2str(k)],'FontSize',7)
    xlabel('Time [ms]','FontSize', 8)
    ylabel ('Knee acc [°/ms²]','FontSize', 8)

    sizePKacc = size(PK_acc2) %2487
    sizexddnorm = size(xdd_norm) %2133

    secondlengthOPENSIM = (length(PK_vel_diff_norm)) - starttimeOS
    secondlengthIMU = (length(xdd_norm)) - starttimeIMU
    endtime2 = secondlengthOPENSIM + starttimeIMU
    % FIGURE 7 CALCULATING DIFFERENCE SCORE OPENSIM DERIVATIVE VELOCITY AND IMU
    %ACC NORM DUS EIGENLIJK FIGUUR 17 VERSCHIL GENOMEN
    figure(7) %nog verschil maken van als ene langer is dan andere
    %subplot(5,1,k)
    if secondlengthIMU > secondlengthOPENSIM
        endtime = secondlengthOPENSIM + starttimeIMU
        plot(PK_vel_diff(starttimeOS:end) - xdd_norm(starttimeIMU:endtime)); hold on;
        xlabel('Time [ms]','FontSize', 8)
        ylabel ('Knee acc [°/ms²]','FontSize', 8)
        title(['Difference IMU Norm & OPENSIM PK derivative velocity SUP HR T0' num2str(k)],'FontSize', 6)
    else endtime = secondlengthIMU + starttimeOS
        plot(PK_vel_diff(starttimeOS:endtime) - xdd_norm(starttimeIMU:end)); hold on;
        xlabel('Time [ms]','FontSize', 8)
        ylabel ('Knee acc [°/ms²]','FontSize', 8)
    title(['Difference IMU Norm & OPENSIM PK derivative velocity SUP HR T0' num2str(k)],'FontSize', 6)
    end

    %%%%%%%%%%%%%%%%%%%% PART TWO %%%%%%%%%%%%%%%%%%%%%%%
    %%% IMU %%%
    addpath ('/MATLAB Drive/BIOMECHLISSA/RAW IMU')
    name4 = sprintf('MATLAB Drive/BIOMECHLISSA/RAW IMU/Sup_HR_Trial0%d_data.mat',k)
    load(name4)
    name5 = sprintf('MATLAB Drive/BIOMECHLISSA/RAW IMU/Sup_HR_Trial0%d_RotAxis_Steer.mat',k)
    load(name5)
    Hinge = name5
    iGyr  = find(strcmp(Data.Tibia.header,'Gyr_X')); % hierin zit onze gyroscoop data dus de hoeksnelheid
    qd    = Data.Tibia.data(224:end,iGyr:iGyr+2); % hoeksnelheden in assenstelsel sensor % ik denk dat die nu Gyr_X, Gyr_Y, Gyr_Z heeft genomen dus 3 kolommen van data
    qTest = qd*Rax'
    length_qTest = length(qTest)

    % FIGURE 8 IMU GYROSCOPE DATA 3 PLOTS
    figure(5);
    time_qtest = 0.01:0.01:length(qTest(839:end,1))/100
    plot(time_qtest,-(qTest(839:end,1)*180/pi),':m'); hold on; % er worden drie roze grafieken gegeven!!! % dit kunnen we ook weer plotten
    plot(time_qtest,-(qTest(839:end,2)*180/pi),'-.m');hold on;
    plot(time_qtest,-(qTest(839:end,3)*180/pi),'m');hold on;

    %%% OPENSIM %%%
    %     dataFolderBK = [startpath '/BODY KINEMATICS/'];
    %     dataFileBK = fullfile(dataFolderBK,['3DGaitModel2354-scaled_BodyKinematics_vel_global_SUP_HR_0' num2str(k) '.sto']);
    %     pathwayBK_vel = dir(dataFileBK);
    %     vel = importdata(fullfile(pathwayBK_vel.folder,pathwayBK_vel.name))
    %     vel_new = -vel.data(starttimeOS:end,17);
    %     time_vel = 0.01:0.01:length(vel.data(starttimeOS:end,1))/100;

    addpath ('/MATLAB Drive/BIOMECHLISSA/BODY KINEMATICS')
    if k == 1
        vel = importdata('3DGaitModel2354-scaled_BodyKinematics_vel_global_SUP_HR_01.sto');
    else
    end
    if k == 2
        vel = importdata('3DGaitModel2354-scaled_BodyKinematics_vel_global_SUP_HR_02.sto');
    else
    end
    if k == 3
        vel = importdata('3DGaitModel2354-scaled_BodyKinematics_vel_global_SUP_HR_03.sto');
    else
    end
    if k == 4
        vel = importdata('3DGaitModel2354-scaled_BodyKinematics_vel_global_SUP_HR_04.sto');
    else
    end
    if k == 5
        vel = importdata('3DGaitModel2354-scaled_BodyKinematics_vel_global_SUP_HR_05.sto');
    else
    end
    vel_new = vel.data(starttimeOS:end,17);
    time_vel = 0.01:0.01:length(vel.data(starttimeOS:end,1))/100;

    %FIGURE 9 PLOT BODY KINEMATICS VELOCITY
    figure(9)
    plot(time_vel,vel_new,'--r'); hold on;
    addpath ('/MATLAB Drive/BIOMECHLISSA/JENTE IK')
    if k == 1
        IK = importdata('Sup_HR_T1.mot');
    elseif k ==2
        IK = importdata('Sup_HR_T2.mot');
    elseif k == 3
        IK = importdata('Sup_HR_T3.mot');
    elseif k == 4
        IK = importdata('Sup_HR_T4.mot');
    elseif k == 5
        IK = importdata('Sup_HR_T5.mot');
    end
    ka = IK.data(432:end,11);
    kv = diff(ka)/0.01;  % OOK OPNIEUW GAAN SYNCHRONISEREN
    plot(IK.data(1:length(kv),1),-kv,'--b'); hold on;
    legend('IMU Angular vel X','IMU Angular vel Y', 'IMU Angular vel Z', 'OPENSIM BK Angular vel', 'OPENSIM IK Derivative of angles','FontSize',6, 'Location', 'Northwest', 'Position',[0.7 0.7 0.1 0.2])
    title('Velocities in the same coordinate system SUP HR T02','FontSize',8)
    xlabel('Time [s]','Position',[12 -310],'FontSize', 8)
    ylabel ('Knee vel [°/s]','Position',[-2 0],'FontSize', 8)

    % FIGURE 10 CALCULATING DIFFERENCE SCORE OPENSIM IK DERIVATIVE AND IMU
    %ANGULAR VELOCITY DUS EIGENLIJK FIGUUR 20 VERSCHIL GENOMEN
    fourthlengthOPENSIM= (length(kv)) - starttimeOS
    endtime4 = fourthlengthOPENSIM + starttimeIMU
    figure(10)
    %subplot(5,1,k)
    plot((qTest(starttimeIMU:endtime4,1)*180/pi) - (kv(starttimeOS:end))); hold on;
    xlabel('Time [ms]','FontSize', 8)
    ylabel ('Knee vel [°/ms]','FontSize', 8)
    title(['Difference IMU Ang vel & OPENSIM IK derivative SUP HR T' num2str(k)],'FontSize', 6)

    thirdlengthOPENSIM= (length(vel_new)) - starttimeOS
    endtime3 = thirdlengthOPENSIM + starttimeIMU
    % FIGURE 11 CALCULATING DIFFERENCE SCORE OPENSIM BK ANGULAR VELOCITY AND IMU
    %ANGULAR VELOCITY DUS EIGENLIJK FIGUUR 20 VERSCHIL GENOMEN
    figure(11)
    %subplot(5,1,k)
    plot((qTest(starttimeIMU:endtime3,1)*180/pi) - (vel_new(starttimeOS:end))); hold on;
    xlabel('Time [ms]','FontSize', 8)
    ylabel ('Knee vel [°/ms]','FontSize', 8)
    title(['Difference IMU Ang vel & OPENSIM BK Ang vel SUP HR T0' num2str(k)],'FontSize', 6)
end

[Matt J]

Much better, but we also cannot run the code it references files, folder paths, and data that we do not have. Please provide a modification of the code that will reproduce the issue without needing to run in your environment. It would also be a good idea if you would copy/paste the errors you are getting so we know what we should expect.

[Lissa]

[Lissa]

Hi, thanks in advance for answering. The loop works if I just put k = 1, but I can an error when i put k = 2. Is it due to the if/else loop used for importdata?

[Stephen23]

Note that rather than using ADDPATH to dynamically add data folders to the MATLAB search path, you should just use absolute/relative filenames (hint: you will need to use FULLFILE). In general the search path should only refer to folders containing code.

[Lissa]

startpath = 'MATLAB Drive/BIOMECHLISSA/';
datapathvel = [startpath 'BODY KINEMATICS/'];
dataFilevel = fullfile(datapathvel,'3DGaitModel2354-scaled_BodyKinematics_vel_global_SUP_HR_0*.sto');
pathwayvel = dir(dataFilevel)
vel = importdata(fullfile(pathwayvel(k).folder,pathwayvel(k).name));

Yes, I already tried that method but was not sure how you could refer to the .data folder of the struct?

[Lissa]

clear all
close all
clc

k = 1
startpath = '/MATLAB Drive/BIOMECHLISSA/';
datapathvel = [startpath 'BODY KINEMATICS/'];
dataFilevel = fullfile(datapathvel,['3DGaitModel2354-scaled_BodyKinematics_vel_global_SUP_HR_0' num2str(k) '.sto'])
pathwayvel = dir(dataFilevel)
vel = importdata(fullfile(pathwayvel.folder,pathwayvel.name));

If I run this in a new blank scipt it works fine and the vel variable is the right struct. When I paste it in the other script it still gives the same error of dot indexing not supported for this variable ..

Answer 1

[Jan]

vel = importdata(...)    

does not create the output vel as a struct in your case. I assume ".sto" files are text files. Then the output ia a matrix.

A bold guess is tha you have to replace

vel_new = vel.data(starttimeOS:end,17);

by

vel_new = vel(starttimeOS:end,17);

[Lissa]

Hi! I tried to run it but it is only working when I write k = 1, it returns the error message when I fill in k = 2 ..

But the files etc are present in the folder for T2 as well .. Thanks in advance!

[Jan]

Please do not post code as screenshot. Posting it as text allows the readers to write an answer by copy&paste.

Your code still contains "vel.data". My suggestion was to omiut the ".data". Did you try this already?

I cannot know, what files type you import. Maybe some ate text files (which are imported as matrices) and others are MAT or XLSX files, which are imported as structs. For efficient work he command importdata is too powerful, because it tries to import the file with automagic guessing of what the user might need. This is finde for a short hack, if the user knows exactly what to do. For scientific work a specific import routine would be much safer.

By the way:

time_vel = 0.01:0.01:length(vel.data(starttimeOS:end,1))/100;

The length of the vector (vel.data(starttimeOS:end,1)) can be determined by:

size(vel.data, 1) - starttimeOD + 1;