How do I avoid using a lot of if statements in a row?

Hi all! I have to execute the content of the following code, which I'm sure can be written in a much more elegant and efficient way. The meaning is clear: for each of the 11 events I'm interested in, if the matrix dffx that corresponds to that event is empty, then it becomes [dffx,num_dff]; otherwise, it becomes [dff1;num_dff]. I am sure that such a trivial work can be executed in way less lines of code. Can you help? Thank you!

    if code_events(i) == 1
        if isempty(dff1)
         dff1=[dff1,num_dff];
        else
        dff1=[dff1;num_dff];
        end
    elseif code_events(i) == 2
        if isempty(dff2)
         dff2=[dff2,num_dff];
        else
        dff2=[dff2;num_dff];
        end
    elseif code_events(i) == 3
         if isempty(dff3)
         dff3=[dff3,num_dff];
        else
        dff3=[dff3;num_dff];
        end
    elseif code_events(i) == 4
           if isempty(dff4)
         dff4=[dff4,num_dff];
           else
        dff4=[dff4;num_dff];
          end
    elseif code_events(i) == 5
        if isempty(dff5)
         dff5=[dff5,num_dff];
           else
        dff5=[dff5;num_dff];
          end
    elseif code_events(i) == 6
         if isempty(dff6)
         dff6=[dff6,num_dff];
           else
        dff6=[dff6;num_dff];
          end
    elseif code_events(i) == 7
           if isempty(dff7)
         dff7=[dff7,num_dff];
           else
        dff7=[dff7;num_dff];
          end
    elseif code_events(i) == 8
          if isempty(dff8)
         dff8=[dff8,num_dff];
           else
        dff8=[dff8;num_dff];
          end
    elseif code_events(i) == 9
          if isempty(dff9)
         dff9=[dff9,num_dff];
           else
        dff9=[dff9;num_dff];
          end
    elseif code_events(i) == 10
          if isempty(dff10)
         dff10=[dff10,num_dff];
           else
        dff10=[dff10;num_dff];
          end
    elseif code_events(i) == 11
         isempty(dff11)
         dff11=[dff11,num_dff];
           else
        dff11=[dff11;num_dff];
    end
    end
end

[krishna kotha]

hii iam krishna

you want short form of code then use loop equation like

for i=0:1:10;

like in c language

[David Hill]

I am confused.

if isempty(dff1)
    dff1=[dff1,num_dff];%there is nothing different between these
else
    dff1=[dff1;num_dff];
end

Why not just:

 switch code_events(i)
     case 1
         dff1=[dff1;num_dff];
     case 2
         dff2=[dff2;num_dff];
 end

It would be better to have a cell array that you could index into instead of having all those variable names. Also you should use code blocks in the MATLAB answers. They are much easier to read and copy.

[Samuele Bolotta]

Thanks for your answer!

What I did now was:

switch code_events(i)
        case 1
            dff1=[dff1;num_dff];
        case 2
            dff2=[dff2;num_dff];
        case 3
            dff3=[dff3;num_dff];
        case 4
            dff4=[dff4;num_dff];
        case 5
            dff5=[dff5;num_dff];
        case 6
            dff6=[dff6;num_dff];
        case 7
            dff7=[dff7;num_dff];
        case 8
            dff8=[dff8;num_dff];
        case 9
            dff9=[dff9;num_dff];
        case 10
            dff10=[dff10;num_dff];
        case 11
            dff11=[dff11;num_dff];   
end

But I'm sure it could be written in three-four lines of code by someone who's more capable than me. What you're proposing is a cell (why a cell if every dff is numerical?) in which I put all the dffs and then I can simply refer to them in terms of their position in the cell?

Thanks!

[Stephen23]

C = {dff1,dff2,...};
for k = 1:numel(C)
    C{k} = [C{k};num_dff];
end

Using numbered variables is usually a sign that your code will be complex and/or inefficient.

[Samuele Bolotta]

Thanks! This is almost what I was looking for, except for the fact that, as you can see in the first code I uploaded, I have 11 code events (1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11) which correspond to 11 behavioural events and 11 dffs. So I have to find a way to link each dff in C with its code event (dff1 with code event 1, dff2 with code event 2...).

Answer 1

[Star Strider]

Another option is switch,case,otherwise. You will need to determine if that is an improvement over the multiple if blocks.

Answer 2

[Steven Lord]

Do you need to have eleven individually numbered variables, or are they all the same size and type (and therefore "stackable" as rows / columns / pages / etc. of a larger array)?

x1 = [ 1;  2;  3;  4];
x2 = [ 5;  6;  7;  8];
x3 = [ 9; 10; 11; 12];
x4 = [13; 14; 15; 16];

x = reshape(1:16, [4 4]); % [x1; x2; x3; x4]

With those examples, it would be much easier to iterate over the columns of x than the individual variables x1, x2, x3, and x4.

If they're not all the same size or not all the same type, consider a cell array.

[Samuele Bolotta]

Thanks for your answer!

No, the eleven variables are all numerical but have different sizes; what I did now was:

switch code_events(i)
        case 1
            dff1=[dff1;num_dff];
        case 2
            dff2=[dff2;num_dff];
        case 3
            dff3=[dff3;num_dff];
        case 4
            dff4=[dff4;num_dff];
        case 5
            dff5=[dff5;num_dff];
        case 6
            dff6=[dff6;num_dff];
        case 7
            dff7=[dff7;num_dff];
        case 8
            dff8=[dff8;num_dff];
        case 9
            dff9=[dff9;num_dff];
        case 10
            dff10=[dff10;num_dff];
        case 11
            dff11=[dff11;num_dff];   
end

But I'm still convinced it coul be improved, in the end the task is very simple and the only difference between the 11 cases is the number. I have 11 code events (1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11) which correspond to 11 behavioural events and 11 dffs. And for each of those 11 code events, its dff gives rise to the matrix with that same structure. I'm looking for an elegant and efficient way to carry out this task!