Elegant way to know in which iteration of for I am

At the moment I have something of the sort:

n_runs=0;
N_categories=[17, 8];
for protocol_ID=[4 1 7 6]
    for t=1:nTrialsPerBlock
        n_runs=n_runs+1;
        if n_runs > N_categories
           (--code--)
        end
        (---code---)
    end
end

What I am looking for is a way to evaluate in which protocol the first for is (meaning if it is in 4, 1, 7 or 6) and then if it is in the first two, should be n_runs > N_categories( 1 ) and if it's the second pair N_categories( 2 ).

I am trying to code it so that it determines in which protocol I am, and according to that evaluate if the number of runs is bigger than the corresponding N_categories. Note that protocol_ID could have any of the numbers (4,1,7,6) in no particular order.

I am not seeing a better way than a bunch of switches/if's. Anyone could give a hand? :)

[per isakson]

See http://c2.com/cgi/wiki?SwitchStatementsSmell.

Switch exists in Matlab because it is more elegant than if-elseif-elseif-etc-end.

[Inês]

I was looking for something other than switch because the instructions on each pair would be equal here. Can a switch work if I do:

switch protocol_ID
   case 1 || 4
   case 6 || 7

?

[per isakson]

See the answer of dpb below.

Answer 1

[dpb]

...Can a switch work if I do:

switch protocol_ID
  case 1 || 4
  case 6 || 7

Not in that exact syntax, no, but

switch protocol_ID
  case {1, 4}
    ...
  case {6, 7}
    ...
  otherwise
    ...

doc switch % etc., for details...

Answer 2

[dpb]

I don't follow what the end objective is from the description, but to know which iteration numerically is being evaluated you've got the indicator variable being incremented in the wrong place--

iter=0;
N_categories=[17, 8];
for protocol_ID=[4 1 7 6]
  iter=iter+1;
  if round(iter/2)==1
    % stuff for first two
  else
    % second two
  end
  ...

[Inês]

Yeah I didn't explain it right, sorry. The thing is protocol_ID is meant to be changed into any order, so it could also be [6, 4, 7, 1] or [4, 1] for example, depending on what the user wants. What I want is to know in which protocol_ID the loop is at the moment, to know which stuff to do. It happens that 4/1 and 6/7 should have the same instructions.

So you see, just counting iterations wouldn't work because I don't want to know how many, just what the current protocol is.

Answer 3

[lvn]

This should do it:

if (protocol_ID==1 ||  protocol_ID==4) && n_runs > N_categories( 1 )
 ..
 elseif (protocol_ID==6 ||  protocol_ID==7) && n_runs > N_categories( 2 )
 ..
end