How do you make a matrix of months??

Hi, if for example you have a lot of dates like this, but a lot more:

727563  
727564  
727565  
727566  
727569  
727570  
727571  
727572
727626  
727627  
727628  
727629  
727632

How can i sort them by month? I was trying to use reshape to make it a 30x12xyears matrix but he biggest problem that i found is that they dont have the same order, i mean some years have like 250 days and other with 260 so if i do reshape then im going to have some days in the incorrect month.

Answer 1

[Walter Roberson]

dv = datevec(YourSerialDateNums);
monthnum = dv(:,2);
grouped_by_month = accumarray(monthnum, YourSerialDateNums(:), [12 1], @(L) {L});

Now grouped_by_month will be a 12 x 1 cell array, one entry for each month, and the data stored there will be the entries from YourSerialDateNums that share that month number, in the same order as encountered in YourSerialDateNums. For example your posted data has entries from January, March, and June.

Answer 2

[Andrei Bobrov]

de = [727563  
727564  
727565  
727566  
727569  
727570  
727571  
727572
727626  
727627  
727628  
727629  
727632];

[~,M] = datevec(de);
[~,ii] = sort(M);
out = de(ii);