How do I find the number of hours?
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Hello,
I have a matrix A with dimensions 35000X1 (datetime). There are hours in matrix A.
For example, 01:00, 05:00, 17:00, 23:00, 05:00, 09:00, ....
How can I find the number of each hour in matrix A. That is, how many hours are there that correspond to 00:00, 01:00,02:00,03:00, .... 21:00,22:00,23:00. Your help is important.
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Accepted Answer
Steven Lord
on 21 Jul 2021
I have a matrix A with dimensions 35000X1 (datetime). There are hours in matrix A.
For example, 01:00, 05:00, 17:00, 23:00, 05:00, 09:00, ....
Are these a datetime array or a duration array?
thisIsADatetime = datetime('now', 'Format', 'HH:mm')
thisIsADuration = duration(12, 5, 0, 'Format', 'hh:mm')
These are not the same, despite looking the same. The thisIsADatetime array has a date associated with it, while thisIsADuration does not. If it's a datetime array you probably want to calculate the time since midnight and compute histcounts on the resulting duration array.
dt = datetime('now') + days(randi([-2 2], 10, 1)) + hours(2*randn(10, 1))
timeSinceMidnight = dt - dateshift(dt, 'start', 'day')
These two histogram plots look very different, since one is binning by hours and one by days.
histogram(timeSinceMidnight, 6)
histogram(dt, 6)
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More Answers (2)
Mudit Chaturvedi
on 21 Jul 2021
Hi!
I understand you are trying to find the frequency of each element in a matrix.
You can use unique() function to get the unique elements and then calculate their frequency using histc or histcounts function
a = unique(A);
sol = [a,histc(A(:),a)];
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