Reordering data based on a separate cell array

I have a data array that i wish to reorder using a cell (string) array to define how data should be reordered. In other words, i need to look at the cell array, work out the necessary reordering steps for this array and then apply the same reordering steps to the data array. My first version of code is long winded, but gets it done. Looking for a much cleaner solution. Here is the code (note: new to cells and structures) to determine reordering approach:

    B=cellfun(@(x) x(1:min(numel(x),2)),act_list,'un',0); %reduces strings to first two letters to distinguish them
%Now 4 arrays to get ordering
fl=[];
ex=[];
hi=[];
un=[];
for i=1:12
if B{i}=='Si' | B{i}=='St' | B{i}=='W'
fl=[fl,i];
 elseif B{i}=='Ou' | B{i}=='Jo'| B{i}=='Ru' | B{i}=='Cy' | B{i}=='El'
    ex=[ex,i];   
elseif B{i}=='In'
    hi=[hi,i];
elseif B{i}=='We'
    un=[un,i];
end
end

How can i clean this up?

[Bob Thompson]

fl = ismember(B{:},'Si','St','w');
ex = ismember(B{:},'Ou','Jo','Ru','Cy','El');
etc...

I don't know that ismember can check for multiple things in the way I have it set up, but basically it will give you a logic array with the locations where the conditions are met. It won't give you the specific numbers like you were making, but you can output the values based on that using something like the following:

A = random(4);
C = A(fl==1); % This will make C only values of A where fl is 1, corresponding to Si, St, and w in B.

Answer 1

[Jos (10584)]

B = {'Si','W','Ou','In','We','Ru','Cy','El','St','Jo', 'In'} % example data

Collections = { {'Si','St','W'},{'Ou','Jo','Ru','Cy','El'},{'In'},{'We'}}

% engine, loop over Collections rather than over B
Loc = cellfun(@(c) find(ismember(B,c)), Collections, 'un', 0)
% fl = Loc{1}, ex = Loc{2} etc.

[Scott McLean]

Thanks! Works perfectly