How to create a variable where certain subjects are coded as 1?

Hi all.

A Matlab beginner here, would appreciate some advice.

I want to create a variable called 'flag_artifact' where certain subjects from my dataset (for whom I know have bad quality images) are coded as e.g., 1. My dataset is stored in a table T with a certain number of rows and 'subject' is the 1st column in the table.

I managed to do it by creating a for loop. Here is what I have:

 flag_artifact = {'T_300'}; 
for i = 1:size(T,1)
    if isequal(table2cell(T1(i, 1)), flag_artifact)
        T(i, 1) = {'1'};
    end
end

Surely there is a more efficient way to do this by perhaps directly creating the variable and using less lines of code? Could anyone give some advice?

Thank you very much!

Answer 1

[Matt J]

flag_artifact=strcmp(T.subject,'T_300');

T.subject(flag_artifact)='1';

[Ivana Kancheva]

Hi, @Matt J - thank you for your answer.

When I try the above, I get an error message ''Conversion to cell from char is not possible.''.

Is there a way to specify multiple subjects in this variable 'flag_artifact' that I would like to code as 1?

[Matt J]

Maybe,

T.subject(flag_artifact)={'1'};

[Ivana Kancheva]

Thank you for this. The line you suggest does work, but what I am unable to do is to specify multiple subjects when defining the variable flag_artifact. For example:

flag_artifact = {'T_300'};  %is there a way to specify multiple subjects here?

I tried using

flag_artifact = {'T_300'}; {'T_301'}
flag_artifact = {'T_300', 'T_301'} 

However, it doesn't work because these subject identifiers do not get replaced with 1s. So the loop always performs the operation for the first defined subject, not for multiple and this is what I am struggling with.

[Matt J]

flagged=ismember(T.subject,{'T_300', 'T_301'});

T.subject(flagged)={'1'};

[Ivana Kancheva]

Hi Matt J.

This is great, thank you! :)

[Matt J]

You are quite welcome, but please Accept-click the answer to certify that it worked.