How I can detection column indexes of string 'rn_mill_tonnage' (n=1,2,3,4....)

I want to use the folloing code to automatic detection column indexes of 'rn_mill_tonnage'(n=1,2,3,4,...n)

For example, run the following code, if the num=1, then the column index of r1_mill_tonnage' is 9 (i.e. col_ind_rn=9)

However, then the num >1, like num=2, we should get the column indexes of r1 and r2 (i.e col_ind_rn=[9,11]) if running the code, but the point is I can only get the column index of r2 (i.e. col_ind_rn=11)

Therefore, how to fix the code and get multiple column indexes of ‘rn_mill_tonnage' when num>1?

Thanks in advance for help!

%% 5.Automatic detection column indexes of 'rn_mill_tonnage'(n=1,2,3,4,...n)
        STR = cell(1,num);%create cell to store multiplr strings
        counter_str = 1;
        for k = 1 : num
                 STR{k} = sprintf('r%d_mill_tonnage',k);
                 col_ind_rn = find(string(G_Value.Properties...
                                   .VariableNames(1: size(G_Value,2))) == STR{k});
        end

Answer 1

[Stephen23]

C = {'X','Y','Z','size(X)','size(Y)','size(Z)','volume','r1_cu_mill_grade','r1_mill_tonnage','r2_cu_mill_grade','r2_mill_tonnage'};
V = str2double(regexp(C,'(?<=^r)\d+(?=_mill_tonnage$)','once','match'))

V = 1×11

NaN NaN NaN NaN NaN NaN NaN NaN 1 NaN 2

find(V<=1)

ans = 9

find(V<=2)

ans = 1×2

9 11

[Chao Zhang]

Thank you so much, help me a lot