Sum of first column based on second column and storing results in a matrix

I have two columns in a matrix.

1st Column : duration

2nd column : Reference Number

I want to add all durations rows for each reference number and store it in a matrix where there is a single duration(sum) along with its unique reference number.

My table looks like below. For example I need a unique summed value of duration for each 3130 reference number. I tried to do it individually using below code but very time consuming. Can anyone please help me to loop it and store result in a matrix? Any guidance on this will be appreciated. Thanks.

idx = A(:,2)==3130;

s = sum(A(idx,1));

[Devansh Patel]

[a,~,c] = unique(A(:,2));

out = [a, accumarray(c,A(:,1))];

I Guess I figured it!

[Adam Danz]

Nice job! Also, splitapply() was designed for this problem; see answer below.

Answer 1

[Adam Danz]

% Create fake data for the demo
A = [rand(30,1),randi(3,30,1)+1000]; 

% Calculate group sum and store in table
[groupID, groups] = findgroups(A(:,2));
groupsum = splitapply(@sum,A(:,1),groupID); 
T = table(groups,groupsum)

Result (will vary due to random draw).

T =
  3×2 table
    groups    groupsum
    ______    ________
     1001       2.122 
     1002      6.1048 
     1003      6.8219