how to find the index of same datetime value
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I have two tables of different sizes of datetime
t = 1251x1 datetime
v = 115x1 datetime with the format of YYYY-MM-DD hh:mmm:ss.SSS as attached below.
I'd like to compare datetime (hh:mmm:ss) without considering .SSS and find the index of the same compared values. Can someone help me with this?
1 commentaire
Stephen23
le 10 Nov 2022
Modifié(e) : Stephen23
le 10 Nov 2022
"I'd like to compare datetime (hh:mmm:ss) without considering .SSS and find the index of the same compared values."
Then use DATESHIFT and ISMEMBER. No loops are required.
DO NOT convert to text and perform text comparisons in complicated nested loops.
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Khushboo
le 7 Nov 2022
Hello,
You can use datestr to convert the datetime to a string (it handles the .SSS part). I am not sure if there is any existing function that can compare different rows of different tables to find rows with identical value in a column. So this is what I have done, I ma sure more efficient solutions might exist:
%assuming the two tables are A,B with first column having the datetime value
A.t = datestr(A.t);
B.t = datestr(B.t);
h1 = height(A);
h2 = height(B);
for i = 1:h1
for j = 1:h2
if strcmp(A{i,1},B{j,1}) == 1
i,j
break
end
end
end
Hope this helps!
4 commentaires
Lei Hou
le 18 Nov 2022
dateset is now in discourage use. You can use [h,m,s] = hms(datetime) to extract time components and then call floor(s) to remove .SSS data.
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Steven Lord
le 7 Nov 2022
Truncate the datetime to the previous whole second then compare.
d = datetime('now');
d.Format = d.Format + ".SSSSSS"
d2 = dateshift(d, 'start', 'second')
d3 = dateshift(d, 'start', 'minute')
2 commentaires
Steven Lord
le 7 Nov 2022
Let's say I want to check if right now is 6:13 PM (and some number of seconds.) In the example below even though d has those "some number of seconds" d3 trims off those seconds. d is not equal to d4, but d3 is.
d = datetime('now');
d.Format = d.Format + ".SSSSSS"
d2 = dateshift(d, 'start', 'second')
d3 = dateshift(d, 'start', 'minute')
d4 = datetime(2022, 11, 7, 18, 13, 0)
isequal(d4, d3)
isequal(d4, d)
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