putting a sequence of text values into a multivariable function.

The problem is easy, but i dont find the solution.

Lets say we want combine some vectors: a1, a2, a3.

  a1 = [1,2,3];
  a2 = [21,22,23];
  a3 = [31,32];
  Comb = combvec(a1,a2,a3);

for that we can use the function Comb = combvec(a1,a2,a3). So the solution is:

a =

1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3

21 21 21 22 22 22 23 23 23 21 21 21 22 22 22 23 23 23

31 31 31 31 31 31 31 31 31 32 32 32 32 32 32 32 32 32

which is the vector of all the posible combinations.

Now, lets supouse that there is a case where we dont know how many vectors we have ( they are generated while running ).

However, we can get a char with the name of those vectors like:

  n = 3;
  final=[];
  
for k=1:3
    if n >= 2
    Data = ['a' num2str(k) ','];
    n=n-1;
    else
    Data = ['a' num2str(k)];
    end
    
    final=strcat(final,Data); 
end

Comb = combvec(final).

And the result of this is operation is a single char: final = ('a1,a2,a3');

But if we try to insert this array into the function like: Comb = combvec(final). We will get this result:

a =

'a1,a2,a3'

Can someone help me to solve it?

Thanks

Answer 1

[Shanmukha Voggu]

Hi Jamie,

I understood that you want to process a char that contains the variable names of matrices separated by commas

This can be achieved by calling combvec multiple times

a1 = [1,2,3];
a2 = [21,22,23];
a3 = [31,32];

% The code below assumes the variable names mentioned in "inputString"
% are already inside the workspace
inputString='a1,a2,a3';
matrixNames=split(inputString,",")% split the string using delimiter as comma

matrixNames = 3×1 cell array
    {'a1'}
    {'a2'}
    {'a3'}

answer=eval(matrixNames{1});% initialize the answer variable
for i = 2:length(matrixNames)
    secondMatrix=eval(matrixNames{i});% evaluate the expression
    answer=combvec(answer,secondMatrix);
end
answer

answer = 3×18

1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 21 21 21 22 22 22 23 23 23 21 21 21 22 22 22 23 23 23 31 31 31 31 31 31 31 31 31 32 32 32 32 32 32 32 32 32

Refer this for more information.