How to count number of days within datetime array

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Louise Wilson 2020-7-8

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评论： Louise Wilson 2020-7-9

I have a timetable which spans a year. The intervals between the datetimes varies from one minute to ten minutes. I am interested in finding out how many days contain any data at all. I tried using histogram but this returns an empty bin on days in which there was no data collected, and so conflates days where there was data collected but the values were 0, and data where there was no data collected.

numberdays=histogram(timetable.DateTime,'BinMethod','day');

This seems like it should be simple but I am sorry I can't figure it out!

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Answer 1

Kanupriya Singh 2020-7-9

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Since your previous attempts are returning you empty data for days that are not in your datetime array, you could calculate the number of days that have any data by using this function-

nnz(x)

This will return you the number of non-zero elements in the array.

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Louise Wilson 2020-7-9

Thanks Kanupriya-I have actually since done this before you replied and it's the only method I have found to work!

Louise Wilson 2020-7-9

[Tally,~,bin]=histcounts(tt,'BinMethod','day'); 
days=nnz(Tally);

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Answer 2

madhan ravi 2020-7-8

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Use retime() with 'daily' 'count' .

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Louise Wilson 2020-7-8

Thanks for your response Madhan. I tried this:

countdays=retime(Kawau_counts,'daily','count');

but it does the same as my attempt above. It lists all days between the first datetime and last datetime in my timetable, and so creates rows for datetimes that never existed in my timetable in the first place.

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