if-else statement for 4 comparison

I want to use if-else & for-loop to make comparison where outputs can be one of four options- TP,TN,FP,FN

Supposed I have two row vectors of whose elements are 1s & 0s.

A= [0;1;0;1;1;0;1];
B= [0;1;1;0;1;1;0];
for i=1:7
    if A(i) ==1 && B(i)==1 
        output TP=1
    elseif A(i) ==1 && B(i)==0
        output FN=1
    elseif A(i) ==0 && B(i)==0
        output TN=1
    else 
        output FP=1
        
    end
end

Unrecognized function or variable 'output'.

I need help on how to properly code this. My idea above is not working

Answer 1

[Cutie]

Thank you @Cris LaPierre @DGM @David Hill for your help. I have been able to navigate it

A= [0;1;0;1;1;0;1;0;0;1];
B= [0;1;1;0;1;1;0;1;0;1];
TP=zeros(1,size(A,1));
TN=zeros(1,size(A,1));
FP=zeros(1,size(A,1));
FN=zeros(1,size(A,1));
for i=1:7
    if A(i) ==1 && B(i)==1 
        TP(i)=1;
    elseif A(i) ==1 && B(i)==0
         FN(i)=1;
    elseif A(i) ==0 && B(i)==0
         TN(i)=1;
    else 
         FP(i)=1;
        
    end
end

Answer 2

[DGM]

You can do it something like this, assuming your inputs are binarized as described.

A = [0;1;0;1;1;0;1];
B = [0;1;1;0;1;1;0];

strmap = {'TN';'FN';'FP';'TP'};
output = strmap(A + 2*B + 1)

output = 7×1 cell array
    {'TN'}
    {'TP'}
    {'FP'}
    {'FN'}
    {'TP'}
    {'FP'}
    {'FN'}

Answer 3

[David Hill]

A= [0;1;0;1;1;0;1];
B= [0;1;1;0;1;1;0];
output=cell(size(A));
output(A==1&B==1)={'TP'};
output(A==1&B==0)={'FN'};
output(A==0&B==0)={'TN'};
output(A==0&B==1)={'FP'};

[Cutie]

@David Hill, thank you for offering your help. However, the vectors can be as much as 50000 rows. So I want it programmed.

[DGM]

It is programmed. David's method uses logical indexing to create one cell array of character vectors which is the same size as A.

A= [0;1;0;1;1;0;1];
B= [0;1;1;0;1;1;0];
output=cell(size(A));
output(A==1&B==1)={'TP'};
output(A==1&B==0)={'FN'};
output(A==0&B==0)={'TN'};
output(A==0&B==1)={'FP'};
output % show the result

output = 7×1 cell array
    {'TN'}
    {'TP'}
    {'FP'}
    {'FN'}
    {'TP'}
    {'FP'}
    {'FN'}

Answer 4

[Cris LaPierre]

I modified your code to run it here and display the error.

You are close, but your syntax is incorrect. Assignment in MATLAB is done with the '='. For example

output = 'TN'

Also, each loop will overwrite the previous ouput value with the new one. Once finished, you will only have the result of the final loop. Use your loop index to assign the current output to a specific location in the vector output. For example

output(i) = 'TN'

[Cutie]

@Cris LaPierre thank you for the 'tip.' It helped me to write the code I want it. I appreciate your help!