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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Steven Lord
2021년 7월 21일
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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Mudit Chaturvedi
2021년 7월 21일
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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stelios loizidis
2021년 7월 21일
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Steven Lord
2021년 7월 21일
Use a vector of bin edges.
dt = datetime('now') + hours(24*rand(10, 1))
timeSinceMidnight = dt - dateshift(dt, 'start', 'day')
histogram(timeSinceMidnight, hours(0:24))
xticks(hours(0:24))
You might want to only display every other tick or change the Format property of the duration array that you pass into xticks.
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