MATLAB: Count occurrences of an event by date

countdate

I am facing an issue with counting number of occurrences by date, suppose I have an excel file where the data are as follows
1/1/2001 23
1/1/2001 29
1/1/2001 24
3/1/2001 22
3/1/2001 23
My preferred output should be
1/1/2001 3
2/1/2001 0
3/1/2001 2
Though 2/1/2001 doesnot appear in the input, I want that included in the output with 0 counts. Thank You!

Best Answer

Try this:
A = {'1/1/2001' 23
     '1/1/2001' 29
     '1/1/2001' 24
     '3/1/2001' 22
     '3/1/2001' 23};
Adt = datetime(A(:,1), 'Format','MM/dd/yyyy');
[H,E] = discretize(Adt, 'month');
Tally = accumarray(H, 1);
Result = table(E(1:numel(Tally))', Tally)                   % Note Transpose Operator (') To Force ‘E’ To Be A Column Vector
Result =
    3×2 table
         Var1       Tally
      __________    _____
      01/01/2001    3    
      02/01/2001    0    
      03/01/2001    2
This works with the data you posted.
Experiment with it with your complete data array to get the result you want.
EDIT — Corrected typographical error in the comment.
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