Introducing a bug in the for loop

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:');
    
    %Setup initial ore and waste matrix respectively
    
    M_ORE = zeros(R1,C1,num);
    
    M_WASTE = zeros(R1,C1);
    
    M_WASTE = array2table(M_WASTE,'VariableNames',M_ROCK.Properties.VariableNames);
    
    STR = cell(1,num);
    
for i = 1 : length(rock)
    
        for j = 1 : num
            
            STR{j} = sprintf('r%d_mill_tonnage',j);
            
            if table2array(M_ROCK(i,STR{j})) > 0  
                
                M_ORE(i,:,j) = table2array(M_ROCK(i,:));
               
            else 
                
                M_WASTE(i,:) = M_ROCK(i,:);
                
                M_WASTE(M_WASTE{:, STR{j}} > 0, :) = [];
            
            end
            
        end
        
end

I think i introduced a bug in the above code, I assume that STR{j}>0 (i.e. 'r1_mill_tonnage' or 'r2_mill_tonnage'), the row will be [ ], and transfer others values from M_ROCK to M_WASTE, but the data in the last row shown in the figure below is not [ ] . And I cannot deal with this.

Answer 1

[Chetan]

Hi @Chao Zhang,

I understand that you're attempting to divide M_ROCK table data into M_ORE and M_WASTE based on user input for rock types. The issue is with deleting M_WASTE rows within the loop, which can misalign indices. To fix this, accumulate row indices to delete first, then remove them after looping.

Here's a revised version of your code:

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:');

%Setup initial ore and waste matrix respectively

M_ORE = zeros(R1,C1,num);
M_WASTE = zeros(R1,C1);
M_WASTE = array2table(M_WASTE,'VariableNames',M_ROCK.Properties.VariableNames);

STR = cell(1,num);
to_remove = []; % Initialize an array to keep track of rows to remove

for i = 1 : length(rock)
    for j = 1 : num
        STR{j} = sprintf('r%d_mill_tonnage',j);
        
        if table2array(M_ROCK(i,STR{j})) > 0  
            M_ORE(i,:,j) = table2array(M_ROCK(i,:));
        else 
            M_WASTE(i,:) = M_ROCK(i,:);
            if table2array(M_WASTE(i,STR{j})) > 0
                to_remove = [to_remove; i]; % Mark row for removal
            end
        end
    end
end

M_WASTE(to_remove, :) = []; % Remove all marked rows at once

Refer to the following MathWorks Documentation :

• https://www.mathworks.com/help/matlab/tables.html
• https://www.mathworks.com/help/matlab/if.html
• https://www.mathworks.com/help/matlab/ref/for.html

Hope it Helps!