MATLAB: How to sum up values in a column of array2 to a column in array1

Question

Hello!

I have two arrays as below;

array1 = [1 2 3 4 5 6 7 8; 9 10 11 12 13 14 15 16 ; 17 18 19 20 21 22 23 24] % 8 columns and 3 rows
array2 = [100; 200; 300] % 1 column 3 rows

I would like to add the values in array2 to the 7th column of array1 to make new array3

array3 = [1 2 3 4 5 6 107 8; 9 10 11 12 13 14 215 16 ; 17 18 19 20 21 22 323 24]

Then I would like to make a new array4 which includes only few of the columns of array3;

array4 = [2 5 6 107; 10 13 14 215 ; 18 21 22 323]

The arrays here are just for illustration. My actual array1 has 8 columns and many(n) rows, while my actual array2 has 1 column and many(n) rows, so I need something that can handle a variable number of rows..

Would be great if someone could give me a helping hand with this!

Thanks a lot in advance!

Answer 1

array1 = [1 2 3 4 5 6 7 8; 9 10 11 12 13 14 15 16 ; 17 18 19 20 21 22 23 24] % 8 columns and 3 rows
array2 = [100; 200; 300] % 1 column 3 rows
array3 =array1 ;
array3(:,7) = array3(:,7)+array2 ;
idx = [1 3 4 8] ;  % remove these columns 
array4 = array3 ;
array4(:,idx) = [] ;