Find datetime in a vector

Asked by Tiago Dias on 16 Aug 2019

Latest activity Commented on by Tiago Dias on 16 Aug 2019

Accepted Answer by KSSV

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t_ref.mat

Hello,

I want to find the index of two times that belong on a colum with a bunch of timedates

t1 = datetime('10-09-2018 00:00:00','Format','dd-MM-uuuu HH:mm:ss')
t2 = datetime('28-09-2018 23:59:00','Format','dd-MM-uuuu HH:mm:ss')
idx_t1 = find(t_ref==t1)
idx_t2 = find(t_ref==t2)

idx_t1 should be 1020961 and idx_t2 1048320, but the results are empty

Thanks

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1 Answer

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Answer by KSSV on 16 Aug 2019

Edited by KSSV on 16 Aug 2019

Accepted Answer

Use ismember

idx = knnsearch(datenum(t_ref),datenum(t1)) ; 
t_ref(idx)
t1

dt = abs((datenum(t_ref)-datenum(t1))) ; 
[val,idx] = min(dt) ;
t_ref(idx)

4 Comments

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Tiago Dias on 16 Aug 2019

Thanks for the knnsearch, that seems to work and give me the index.

Any idea with the other two functions doesnt work?

Guillaume on 16 Aug 2019

Any idea with the other two functions doesnt work?

Because, despite your statement, neither t1 nor t2 are present within t_ref. Note that the 'Format' property has no influence on the actual content of the datetime, so if they differ at the millisecond level, == will return false, even though you're not displaying the milliseconds.

If you want to get rid of the milliseconds:

t_ref.Second = floor(t_ref.Second); %or round if you prefer rounding to the nearest second

Tiago Dias on 16 Aug 2019

oh ok, I though he would ignore the miliseconds due to the format I specified.

thanks

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