MATLAB: Avoiding many if-Statetments in a for-loop

if statementMATLAB

Hello everyone 🙂
I would like to run a for-loop over a vector. What to do with each element in the vector depends on many if-else statements. I simplified it like this:
clear variables;
rng default;
V1 = rand(365,1);
V2 = rand(365,1);
V2 = V2 <= 0.5;
V3 = rand(365,1);
V3 = V3 <= 0.3;
Vresult = zeros(length(V1),1);
tstart = 1;
tend = length(V1);
for t = tstart:tend    
    if V2(t) == 1        
        if V3(t) == 1            
            Vresult(t) = do_stuff(V1(t));            
        else            
            Vresult(t) = do_different_stuff(V1(t));            
        end    
    else        
        if V3(t) == 1            
            Vresult(t) = do_even_different_stuff(V1(t));            
        else            
            Vresult(t) = do_even_more_different_stuff(V1(t))            
        end
    end
end
function [var_out] = do_stuff(var_in)
var_out = var_in * 5;
end
function [var_out] = do_different_stuff(var_in)
var_out = var_in + 3;
end
function [var_out] = do_even_different_stuff(var_in)
var_out = var_in / 4;
end
function [var_out] = do_even_more_different_stuff(var_in)
var_out = var_in - 2;
end
With even more if-else conditions and more calculations per statement it gets really confusing and unreadable. And I feel like I'm writing the same code over and over again as only some parts of the code are different in each statement and other parts stay the same.
How can I make my code more efficient, easier to read and maintainable? Sorry if this should be common knowledge 😀

Best Answer

I'm assuming the local functions provided are just demo functions. If those functions can be vectorized, it's very likely that you don't need a loop or any conditional statements at all.
Here's a method of performing a function on each element of vector V1 based on the values of V2(n) and V3(n) which are both logical vectors. It uses a switch-case instead of a series of conditional statements. The switch expression must be a scalar or char vector which is why I'm converting the logical values to char where 1 is true and 0 is false. 
VAll = [V2,V3]; 
for t = tstart:tend
    switch sprintf('%d %d',VAll(t,:))
        case '1 1'
            Vresult(t) = do_stuff(V1(t));
        case '1 0'
            Vresult(t) = do_different_stuff(V1(t));
        case '0 1'
            Vresult(t) = do_even_different_stuff(V1(t));
        case '0 0'
            Vresult(t) = do_even_more_different_stuff(V1(t)); 
        otherwise
            % This should never happen unless VAll is unexpected
            error('Something is unexpected about the internal variable ''VAll''.')
    end
end
Related Question