regarding files from directory

I have 156 different files in one folder , out of which I need to read first 13 files only and then start reading from 14 to 26 so on till 156. e.g v_1970_ch4.nc v_1970_ch4_1.nc v_1970_ch4_2.nc . .

v_1970_ch4_13.nc

v_1980_ch4_1.nc v_1980_ch4_1.nc v_1980_ch4_2.nc . .

v_1980_ch4_13.nc

I need to add data together for every 13 files, so how I can set for loop ?

[Edit: moved code from comment]

 dir_list =dir('v41_CH4*');

 k=0; 
 for i=1:length(dir_list) 
 vec1=zeros(720,360); 
 for j =1:13 
 k=k+1; 

 ncid=netcdf.open(dir_list(k).name,'NOWRITE'); 

 latid=netcdf.inqVarID(ncid,'lat'); 
 latitude=double(netcdf.getVar(ncid,latid)); 

 lonid=netcdf.inqVarID(ncid,'lon'); 
 longitude=double(netcdf.getVar(ncid,lonid)); 

 emi_ch4id=netcdf.inqVarID(ncid,'emi_ch4'); 
 ch4=double(netcdf.getVar(ncid,emi_ch4id));

 vec1=(vec1+ch4);

 end 
 end

[Jan]

It is always a good idea to post, what you have done so far. Then we can re-use as much code as possible and do not confuse you by using different names for variables etc.

Answer 1

[Jan]

Does alphabetical sorting create the wanted order? Or are there problems like in:

sort({'1', '2', '9', '10', '11'})
>> '1'    '10'    '11'    '2'    '9'

[Uday]

I think in this case alphabetical order will not work because every time I need to read 1:13 and then 14:26.......156