How to take monthly flow data and obtain annual max flow values

I have a data set with months (numbered from 1 to 12) in column 1 and monthly max flows in column 2. I would like to obtain the yearly maximum flows over the entire 81 year span (972 months) of this dataset. Essentially, for every 12 months (1-12) I would like to find a maximum and then I would like to compile these 81 flows (the month of max occurrence in a year does not matter to me). Any tips on how I might go about this?

           1       36000
           2      218000
           3       24300
           4       43200
           5        8430
           6        2230
           7         535
           8         205
           9         110
          10         100
          11        4220
          12       18100
           1        6680
           2       53600
           3       27000
           4       20100
           5        2030
           6         680
           7         150
           8          80
           9         120
          10         144
          11        4500
          12        7020
     

Answer 1

[Ajay Kumar]

Your data being X,

data = X(:,2);
yearly_max = zeros(length(data)/12,1);
j=1;
for i=1:length(data)/12
    yearly_max(i)=max(data((j:j+11),1));
    j=j+12;
end

Here, I have neglected the first column in X (your matrix), as it is of no use.

Please accept the answer, if you got what you need. Thanks :)

Answer 2

[Akira Agata]

Assuming your data was stored in 972-by-2 matrix yourData, following code can do your task.

year = repelem([1:81]',12,1);
yearlyMax = splitapply(@max,yourData(:,2),year);

By the way, if you will do some more analysis on your data, I would recommend creating datetime vector and storing your data as timetable variable.