Subtracting elements within a table

I have a table:

1       23
2       24
3       21
4       34
1       89
2       23.2
3       34.8
4       -23.1

and it continues with the first column always being in the sequence 1-2-3-4.

I need to subract the first element next to 1 from the second element next to 1, so: 89-23. Then all elemets represented by the number 2 in the 1st column, so: 23.2-24. etc.

The outcome should be the following vector: [66 -0.8 13.8 -57.1].

Answer 1

[Arif Hoq]

A=[1       23
2       24
3       21
4       34
1       89
2       23.2
3       34.8
4       -23.1];
My_Table= table(A(:,1),A(:,2))

My_Table = 8×2 table
    Var1    Var2 
    ____    _____

     1         23
     2         24
     3         21
     4         34
     1         89
     2       23.2
     3       34.8
     4      -23.1

B=table2array(My_Table(:,2));
ind1 = 1:4;
ind2 = ind1 + 4;
output=B(ind2)-B(ind1)

output = 4×1

66.0000 -0.8000 13.8000 -57.1000

[Lu Da Silva]

worked perfectly, thanks!

Since the table is actually longer, I made a small adjustment:

ind1 = 1:length(B)-4;