How to find (i) unique datetimes and (ii) count their occurences?

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Sim
Sim 2023-6-14
回答： Sim 2023-6-14
Ran in:
How to find (i) unique datetimes and (ii) count their occurences?
% Input
a = [{'22-Jun-2023 09:00:00'}
{'23-Jun-2023 19:00:00'}
{'24-Jun-2023 16:00:00'}
{'24-Jun-2023 11:00:00'}
{'19-Jun-2023 16:00:00'}
{'20-Jun-2023 10:00:00'}
{'21-Jun-2023 10:00:00'}
{'22-Jun-2023 09:00:00'}
{'23-Jun-2023 14:00:00'}
{'19-Jun-2023 17:00:00'}
{'20-Jun-2023 11:00:00'}
{'21-Jun-2023 17:00:00'}
{'22-Jun-2023 15:00:00'}
{'23-Jun-2023 06:00:00'}
{'24-Jun-2023 11:00:00'}
{'25-Jun-2023 19:00:00'}
{'20-Jun-2023 11:00:00'}
{'21-Jun-2023 09:00:00'}
{'23-Jun-2023 12:00:00'}
{'25-Jun-2023 17:00:00'}
{'23-Jun-2023 12:00:00'}
{'22-Jun-2023 07:00:00'}];
% My attempt:
% (1) Get datetime from cells
b = datetime(a,'InputFormat','dd-MMM-yyyy HH:mm:ss');
% (2) Get unique dates
[~, inds] = unique(datestr(b, 'yyyymmdd'), 'rows', 'stable');
uniqueDates = sort(b(inds))
uniqueDates = 7×1 datetime array
19-Jun-2023 16:00:00 20-Jun-2023 10:00:00 21-Jun-2023 10:00:00 22-Jun-2023 09:00:00 23-Jun-2023 19:00:00 24-Jun-2023 16:00:00 25-Jun-2023 19:00:00
% (3) Count occurences for each date
occurences = groupsummary(table(b),1)
occurences = 18×2 table
b GroupCount ____________________ __________ 19-Jun-2023 16:00:00 1 19-Jun-2023 17:00:00 1 20-Jun-2023 10:00:00 1 20-Jun-2023 11:00:00 2 21-Jun-2023 09:00:00 1 21-Jun-2023 10:00:00 1 21-Jun-2023 17:00:00 1 22-Jun-2023 07:00:00 1 22-Jun-2023 09:00:00 2 22-Jun-2023 15:00:00 1 23-Jun-2023 06:00:00 1 23-Jun-2023 12:00:00 2 23-Jun-2023 14:00:00 1 23-Jun-2023 19:00:00 1 24-Jun-2023 11:00:00 2 24-Jun-2023 16:00:00 1
% Desired Output
uniqueDates =
19-Jun-2023
20-Jun-2023
21-Jun-2023
22-Jun-2023
23-Jun-2023
24-Jun-2023
25-Jun-2023
occurences =
19-Jun-2023 2
20-Jun-2023 3
21-Jun-2023 3
22-Jun-2023 4
23-Jun-2023 5
24-Jun-2023 3
25-Jun-2023 2

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回答（1 个）

Sim
Sim 2023-6-14
Ran in:
I might have found a solution/workaround, but if there are more compact, correct and robust methods I will accept them!
a = [{'22-Jun-2023 09:00:00'}
{'23-Jun-2023 19:00:00'}
{'24-Jun-2023 16:00:00'}
{'24-Jun-2023 11:00:00'}
{'19-Jun-2023 16:00:00'}
{'20-Jun-2023 10:00:00'}
{'21-Jun-2023 10:00:00'}
{'22-Jun-2023 09:00:00'}
{'23-Jun-2023 14:00:00'}
{'19-Jun-2023 17:00:00'}
{'20-Jun-2023 11:00:00'}
{'21-Jun-2023 17:00:00'}
{'22-Jun-2023 15:00:00'}
{'23-Jun-2023 06:00:00'}
{'24-Jun-2023 11:00:00'}
{'25-Jun-2023 19:00:00'}
{'20-Jun-2023 11:00:00'}
{'21-Jun-2023 09:00:00'}
{'23-Jun-2023 12:00:00'}
{'25-Jun-2023 17:00:00'}
{'23-Jun-2023 12:00:00'}
{'22-Jun-2023 07:00:00'}];
% Get datetime from cells
b = datetime(a,'InputFormat','dd-MMM-yyyy HH:mm:ss','Format','dd-MMM-yyyy');
c = dateshift(b, 'start', 'day');
% Get unique dates
[~, inds] = unique(datestr(c, 'yyyymmdd'), 'rows', 'stable');
uniqueDates = sort(c(inds))
uniqueDates = 7×1 datetime array
19-Jun-2023 20-Jun-2023 21-Jun-2023 22-Jun-2023 23-Jun-2023 24-Jun-2023 25-Jun-2023
% Count occurences for each date
d = groupsummary(table(c),1)
d = 7×2 table
c GroupCount ___________ __________ 19-Jun-2023 2 20-Jun-2023 3 21-Jun-2023 3 22-Jun-2023 4 23-Jun-2023 5 24-Jun-2023 3 25-Jun-2023 2

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