How to divide the original matrix into different matrices according to the strings

My idea is create the 'M_ROCK' matrix if the rock_index ==2 (i.e. there are multiple rock types in the model). And then input the number of rock types according to the 'M_ROCK'. The following picture is the screenshot of part M_ROCK.

For example, there are two rock types r1 and r2 in 'M_ROCK', the num then will be input 2, and the values in the 'M_ROCK' will be transferred to the corresponding new matrix M_ORE(this might include M_ORE1 and M_ORE2) and M_WASTE, according to the strings 'r1_mill_tonnage' and 'r2_mill_tonnage'. However, when I run the following code, there is an error 'Row index exceeds table dimensions'.

In this case, there are only two types of rocks, there may be three, four, etc. other situations, how to write a code, can summarize these situations. In other words, input the number of rock types, the values will automically transfer into the corresponding M_ORE (ORE1,ORE2,...) and M_WASTE according to the strings 'rn_mill_tonnage'(n=1,2,3,....)

Thanks in advance for your help!

elseif rock_index == 2
%%  
    M_ROCK = rock;
    M_ROCK = array2table(M_ROCK,'VariableNames',G_Value.Properties.VariableNames);

%Enter the number of rock types and then create the corresponding 
%ore matrixs,after determining the multiple rock types 

num=input('Please enter the number of rock types:');

%6.Extract ore and waste matrix from ROCK matrix(multiple rock types)
%Setup initial ore and waste matrix respectively

M_WASTE = zeros(R1,C1);%waste matrix for multiple rock types
M_ORE = zeros(R1,C1);

for j = 1 : num
    
    STR = cell(1,num);
    
    STR{j} = sprintf('r%d_mill_tonnage',j);
    
    if table2array(M_ROCK(i,STR{j}))>0
        
        M_ORE(i,:) = table2array(M_ROCK(i,:));
        
        for k = 1:num
        
         M_ORE = zeros(R1,C1,num);
        
        end
        
    else
        
         M_WASTE(i,:)=table2array(M_ROCK(i,:));
         
    end
    
end

[Stephen23]

https://www.mathworks.com/matlabcentral/answers/304528-tutorial-why-variables-should-not-be-named-dynamically-eval

[Chao Zhang]

Thanks! But can my idea be realized with matlab?

[Walter Roberson]

    STR = cell(1,num);

That should not be within the for j loop.

Answer 1

[Sulaymon Eshkabilov]

Hi,

Here are some corrections made in your code:

..
STR = cell(1,num);
M_ORE = zeros(R1,C1,num);
for j = 1 : num  
    STR{j} = sprintf('r%d_mill_tonnage',j);
    
    if table2array(M_ROCK(i,STR{j}))>0
        
        M_ORE(j,:) = table2array(M_ROCK(j,:));     % not "i" but "j"
              
    else
        
         M_WASTE(j,:)=table2array(M_ROCK(j,:));   % not "i" but "j"
         
    end
    
end

[Chao Zhang]

Thanks for your answer! But this line ' if table2array(M_ROCK(i,STR{j}))>0' has an error Row index exceeds table dimensions