How to extract specific dates from a datetime table?
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Ashfaq Ahmed am 19 Apr. 2023
I have a datetime table (DATE1.mat) containing some dates from 1984 to 2022 at 10:00 am. I have another date timetable (DATE2.mat) that contains data from 2005 to 2019 at 10:00 am with temperature values. Can anyone please tell me how to find only the dates from DATE2.mat file that belong to DATE1.mat list?
Any feedback will be greatly appreciated!
Les Beckham am 19 Apr. 2023
found_date_idx = ismember(datet, B.Time); % logical indexes for dates in datet that are found in B
B_selected = B(found_date_idx, :) % extract the rows from B that match the found dates
Weitere Antworten (2)
Eric Sofen am 20 Apr. 2023
If you know all the datetimes have 10:00:00 time components and you're just matching dates, timetable subscripting does that directly. Of course, if you're concerned about wanting non-exact matches (e.g. to match things that occur on the same date but not the same time), then the approach suggested by Adam is helpful. Other approaches for dealing with inexact matches may involve retime, timerange, or withtol.
Adam Danz am 19 Apr. 2023
Datetimes are rounded down to the start of the day using dateshift. Then, ismember finds matches between the two sets of dates.
load DATE1.mat % datet (vector)
load DATE2.mat % B (table)
[isDateMatch, idx] = ismember(dateshift(datet,'start','day'),dateshift(B.Time,'start','day'));
B.Time(idx(isDateMatch)) corresponds with datet(isDateMatch)
This line verifies that they are equal.
isequal(dateshift(B.Time(idx(isDateMatch)),'start','day') , dateshift(datet(isDateMatch),'start','day'))