MATLAB: How to consolidate rows with same value, while adding their cells

if statement

I have NOAA climate data reported every 15 minutes and need to consolidate it into daily info. I want to add cells at the end of a row together that have the same date, and make a new matrix with the 'summed' and consolidated info. Here is a rough example of what I want to do:
FROM:
[date, precip
2/1,    4
2/1,    5
2/1,    6
2/2,    2
2/2,    3
2/2,    1
2/2,    4]
TO:
[date, precip
2/1,    15
2/2,    10]

Best Answer

clear
d = {'date', 'precip'; '2/1', 4; '2/1', 5; '2/1', 6; '2/2', 2; '2/2', 3; '2/2', 1; '2/2',4}
dates  = {d{2:end,1}};
amount = [d{2:end,2}];
[uniqueDates, firstInd, allInd] = unique(dates);
for i = 1:numel(firstInd)
    totalRain(i) = sum(amount(allInd == i));
end
disp(uniqueDates)
disp(totalRain)
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