Filtering a table with datatime on dates

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Niels Hawinkel
Niels Hawinkel 2021-7-28
回答： Scott MacKenzie 2021-7-28
I have a table(=tmp) with column 2 (=Var2) consisting of Datetimes (Year-Month-Day-HH-MI-S). There are multiple days in this column and I want to filter out 1 day (i.e. 2019-10-01). I have tried the following:
Filter = tmp(tmp.Var2==datetime(2019,10,1,:,:,:),:);
I get the following error:
Unrecognized function or variable 'datetime'.
I have also tried the following:
Filter = tmp(tmp.Var2==datetime(2019,10,1),:);
which results in an empty table.
Anybody knows what to do?
Thank you in advance.

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采纳的回答

Cris LaPierre
Cris LaPierre 2021-7-28
编辑：Cris LaPierre 2021-7-28
In the first case, you are not using correct syntax for MATLAB's datetime function (it doesn't accept colons), so MATLAB is assuming you must have your own function or variable that does, but it can't find it.
In the second case, the == is looking for an exact match (when you don't specify time, midnight is used). None of your datetimes is an exact match.
If you are not looking for an exact match, use conditional statements instead of ==.
rmvDate = tmp.Var2 >= datetime(12019,10,1,0,0,0) & tmp.Var2 < datetime(12019,10,2,0,0,0);
Filter = tmp(rmvDate,:);

更多回答（2 个）

Rik
Rik 2021-7-28
There is probably a native way to do this, but you could also do it yourself:
ref=datetime(2019,10,1);
L=day(ref)==day(tmp.Var2) & month(ref)==month(tmp.Var2) & year(ref)==year(tmp.Var2);
Filter = tmp(L,:);
Scott MacKenzie
Scott MacKenzie 2021-7-28
To remove rows corresponding to 2019-10-01, this should work:
d = datetime(2019,10,01);
removeLogical = isbetween(tmp.Var2, d, d+1);
tmp(removeLogical,:) = [];

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