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

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

For example, run the following code, if the num=1, then the column index of rk_accept_metal1' is 9 (i.e. col_ind=9)

Then, the num >1, like num=2, we should get the column indexes of r1 and r2 (i.e col_ind=[9,11]) if running the code

  %Determine the column index of variable names
  match_var1 = str2double(regexp(var_nm.Properties.VariableNames, '(?=rk_accept_)+((?<=^metal)\d)$','once','match'));
  ind_rmg = find(match_var1 <= num1);

But i cannot get anything if i use this code, i think the point is '(?=rk_accept_)+((?<=^metal)\d)$', but i have no idea how to fix it

Thanks in advance for help!

[Mathieu NOE]

hello

it could be helpful if you share the input data as well (var_nm.Properties.VariableNames)

[Chao Zhang]

'X' 'Y' 'Z' 'X_size' 'Y_size' 'Z_size' 'volume' 'block_tonnage' 'rk_accept_grade1' 'rk_accept_metal1' 'rk_rejected_grade1' 'rk_rejected_metal1' 'rk_accept_grade2' 'rk_accept_metal2' 'rk_rejected_grade2' 'rk_rejected_metal2' 'rk_accept_tonnage' 'rk_rejected_tonnage' 'sg' 'volume_factor'

Answer 1

[Stephen23]

C = {'X','Y','Z','X_size','Y_size','Z_size','volume','block_tonnage','rk_accept_grade1','rk_accept_metal1','rk_rejected_grade1','rk_rejected_metal1','rk_accept_grade2','rk_accept_metal2','rk_rejected_grade2','rk_rejected_metal2','rk_accept_tonnage','rk_rejected_tonnage','sg','volume_factor'};
N = str2double(regexp(C, '(?<=rk_accept_metal)\d+$','once','match'))

N = 1×20

NaN NaN NaN NaN NaN NaN NaN NaN NaN 1 NaN NaN NaN 2 NaN NaN NaN NaN NaN NaN