find beginning and end of events in a loop

Hi,

i have the diameter left and right (DialL and DialR) and the variable TOBII_Stim (=Stimulus).

I am trying to extract the DialL and DialR that correspon to specific condtions presents in the variable TOBII_Stim. For example, i have to extract the diameter L and R that goes from the beginning of the condition "Croix grise 200" until the end of the condition "Croix grise 200".

to do so, i created two empy variables that i will fulfill with the index of my beginning and end condition:

index_trial=[];
index_trial_end=[];
for i=1:length(TOBII_Stim)
    if TOBII_Stim(i) == "Croix grise 200.jpg"  
        index_trial(end+1) = i;
        
    elseif TOBII_Stim(i) == "Croix grise 85.jpg"
        index_trial(end+1) = i;
        
    elseif TOBII_Stim(i) == "Croix grise 255.jpg"
        index_trial(end+1) = i;
        
    elseif TOBII_Stim(i) == "RichText4.rtf"
        index_trial(end+1) = i;
        
    elseif TOBII_Stim(i) == "RichText3.rtf"
        index_trial(end+1) = i;
        
    elseif TOBII_Stim(i) == "RichText2.rtf"
        index_trial(end+1) = i; 
        
    elseif TOBII_Stim(i) == "RichText1.rtf"
        index_trial(end+1) = i;
        
    end
end

i tried several things to find the end but i have errors saying that values must be integers.

Could please somebody help me out with understanding how to find the END of each condition and fulfill the variable index_trial_end=[]; ?

thnak you in advance

[Matt J]

Please provide example input variables and the desired output.

[GB92_R]

Hi Matt J,

i preferred to copy paste my work space to show you on which variable i am working on. I opened only DialL and TOBII stim to swhow you how they look like.

the objective is to fullfill the empty variable in this way:

for i=1:(length(index_trial)-1)

Trial{i}.index=index_trial(i);

Trial{i}.stim=TOBII_Stim(index_trial(i));

Trial{i}.baseline=(DiaL_LPF(index_trial(i)-65:index_trial(i)-1)+DiaR_LPF(index_trial(i)-65:index_trial(i)-1))/2;

Trial{i}.TIMEbaseline=TimeTOBII(index_trial(i)-65:index_trial(i)-1);

Trial{i}.timecourse=(DiaL_LPF(index_trial(i):index_trial(i)+1500)+DiaR_LPF(index_trial(i):index_trial(i)+1500))/2;

Trial{i}.TIMEtimecourse=TimeTOBII(index_trial(i):index_trial(i)+1500);

end

i=length(index_trial);

Trial{i}.index=index_trial(i);

Trial{i}.stim=TOBII_Stim(index_trial(i));

Trial{i}.baseline=(DiaL_LPF(index_trial(i)-65:index_trial(i)-1)+DiaR_LPF(index_trial(i)-65:index_trial(i)-1))/2;

Trial{i}.TIMEbaseline=TimeTOBII(index_trial(i)-65:index_trial(i)-1);

Trial{i}.timecourse=(DiaL_LPF(index_trial(i):end)+DiaR_LPF(index_trial(i):end))/2;

Trial{i}.TIMEtimecourse=TimeTOBII(index_trial(i):end);

%% save trials

save(Path_File(1:end-5),'Trial');

Answer 1

[Divyanshu]

The reason for the error is that ‘TOBII_Stim’ is a cellular array and you are trying to access the elements of the cellular array using parenthesis () instead the cellular array elements should be accessed using angular brackets {}.

Have a look at the below sample code for better understanding:

index_trial=[];
index_trial_end=[];
TOBII_Stim = {"Validation.jpg" "RichText4.rtf" "Croix grise 200.jpg" "Croix grise 500.jpg" "Validation.jpg"}';
for i=1:length(TOBII_Stim)
    if TOBII_Stim{i} == "Croix grise 200.jpg"  
        index_trial(end+1) = i;
        
    elseif TOBII_Stim{i} == "Croix grise 85.jpg"
        index_trial(end+1) = i;
        
    elseif TOBII_Stim{i} == "Croix grise 255.jpg"
        index_trial(end+1) = i;
        
    elseif TOBII_Stim{i} == "RichText4.rtf"
        index_trial(end+1) = i;
        
    elseif TOBII_Stim{i} == "RichText3.rtf"
        index_trial(end+1) = i;
        
    elseif TOBII_Stim{i} == "RichText2.rtf"
        index_trial(end+1) = i; 
        
    elseif TOBII_Stim{i} == "RichText1.rtf"
        index_trial(end+1) = i;
        
    end
end
index_trial

Please refer the following documentation for further information:

Access Data in Cell Array - MATLAB & Simulink (mathworks.com)