All possible combinations of strings MATLAB

Question

UPD: I wish to say sorry to the StackOverflow community for asking a question without making effort to solve the problem by myself. From now on, I'll ask questions only if I really have serious problem

I am now developing the program that generates all the possible permutations of string elements:

I started with:

A = ['Bridge','No Bridge'];
B = ['Asphalt','Concrete','Combined'];
C = ['Fly Ash',' Sulphur','Nothing'];
D = ['Two lanes','Four lanes with barriers'];
E = ['Paid','Non-paid'];
F = ['Mobile','Non-mobile'];
N = length(A)*length(B)*length(C)*length(D)*length(E)*length(F);
out = zeros(N,6);

But now I'm stuck with what to do next. The output needed is something like:

out = 

    'Bridge' 'Asphalt' 'Fly Ash' 'Two lanes' 'Paid' 'Mobile'
    'Bridge' 'Asphalt' 'Fly Ash' 'Two lanes' 'Paid' 'Non-mobile'
    'Bridge' 'Asphalt' 'Fly Ash' 'Two lanes' 'Non-paid' 'Mobile'
    'Bridge' 'Asphalt' 'Fly Ash' 'Two lanes' 'Non-paid' 'Non-mobile' etc

Please, could you suggest the most efficient way to do this?

Answer 1

First, note that in Matlab, the following square bracket notation: ['Hello', 'World'], does not in fact create an array of string, but concatenates the strings "Hello" and "World" to yield 'HelloWorld'. So, in this case, you should use Cell Arrays instead: A = {'Hello', 'World'} (note the curly brackets).

To answer your question:
Although you could go for something more generic (which you should in real-life code), for now, since you know the arrays of hand, you can simply create nested for loops like this:

A = {'Bridge','No Bridge'};
B = {'Asphalt','Concrete','Combined'};
...    
for aIndex = 1:length(A)
    for bIndex = 1:length(B)
        % add more loop levels here
        fprintf([A{aIndex}, ',', B{bIndex}, '\n']);
    end
end

With ouput:

Bridge,Asphalt
Bridge,Concrete
Bridge,Combined
No Bridge,Asphalt
No Bridge,Concrete
No Bridge,Combined

Answer 2

Use ndgrid to generate all combinations of the indices, and then use those indices to build the result from the strings:

A = {'Bridge','No Bridge'};
B = {'Asphalt','Concrete','Combined'};
C = {'Fly Ash',' Sulphur','Nothing'};
D = {'Two lanes','Four lanes with barriers'};
E = {'Paid','Non-paid'};
F = {'Mobile','Non-mobile'}; %// data. Cell arrays of strings

[a b c d e f] = ndgrid(1:numel(A),1:numel(B),1:numel(C),1:numel(D),1:numel(E),1:numel(F));
out = [A(a(:)).' B(b(:)).' C(c(:)).' D(d(:)).' E(e(:)).' F(f(:)).'];

Or, if you need the results in the order of your example:

[f e d c b a] = ndgrid(1:numel(F),1:numel(E),1:numel(D),1:numel(C),1:numel(B),1:numel(A));
out = [A(a(:)).' B(b(:)).' C(c(:)).' D(d(:)).' E(e(:)).' F(f(:)).'];

This gives

out = 

    'Bridge'       'Asphalt'     'Fly Ash'     'Two lanes'    'Paid'        'Mobile'    
    'Bridge'       'Asphalt'     'Fly Ash'     'Two lanes'    'Paid'        'Non-mobile'
    'Bridge'       'Asphalt'     'Fly Ash'     'Two lanes'    'Non-paid'    'Mobile'    
    'Bridge'       'Asphalt'     'Fly Ash'     'Two lanes'    'Non-paid'    'Non-mobile'
    ...

Answer 3

Though it's not the case in the question asked, but if A, B, C, D, E and F were two element cell arrays, then we could use few dirty tricks -

num1 = (num2str(111111+str2num(dec2bin(0:63))) - '0')';
comp1 = cell(size(num1,2),6);
for k = 1:size(num1,2)
    comp1(k,:) = [A(num1(1,k)) B(num1(2,k)) C(num1(3,k)) D(num1(4,k)) E(num1(5,k)) F(num1(6,k))];
end