Matlab: Series of Variables in a Loop - matlab

Question

This is a solution from another stackoverflow participant who helped me out.
Data is coming from a csv file:
States Damage Blizzards
Indiana 1 3
Alabama 2 3
Ohio 3 2
Alabama 4 2
%// Parse CSV file
[States, Damage, Blizzards] = textread(csvfilename, '%s %d %d', ...
'delimiter', ',', 'headerlines', 1);
%// Parse data and store in an array of structs
[U, ix, iu] = unique(States); %// Find unique state names
S = struct('state', U); %// Create a struct for each state
for k = 1:numel(U)
idx = (iu == k); %// Indices of rows matching current state
S(k).damage = Damage(idx); %// Add damage information
S(k).blizzards = Blizzards(idx); %// Add blizards information
end
In MATLAB, I need to create a series of assigned variables (A1,A2,A3) in a loop. So I have structure S with 3 fields: state, tornado, hurricane.
Now I have attempted this method to assign A1 =, A2 =, which I got an error because it will not work for structures:
for n = 1:numel(S)
eval(sprintf('A%d = [1:n]',S(n).states));
end
Output goal is a series of assigned variables in the loop to the fields of the structure:
A1 = 2 3
A2 = 2 3
A3 = 4 5

Answer 1

I'm not 100% sure I understand your question.
But maybe you are looking for something like this:
for n = 1:numel(S)
eval(sprintf('A%d = [S(n).damage S(n).blizzards]',n));
end
BTW using evalc instead of eval will suppress the command line output.
A little explanation, why
eval(sprintf('A%d = [1:n]',S(n).state));
does not work:
S(1).state
returns
ans =
Alabama
which is a string. However,
A%d
expects a number (see this for number formatting).
Additionally,
numel(S)
yields
ans =
3
Therefore,
eval(sprintf('A%d = [1:n]',n));
will simply return the following output:
A1 =
1
A2 =
1 2
A3 =
1 2 3
Hence, you want n as a counter for the variable name, but compose the vector of the entries in the other struct-fields (damage and blizzards), again, using n as a counter.