How to locate the index of a certain date for a date-time array?
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Hello,
I have a date-time array, 'dt' that is recorded hourly for a whole year.
The first three data points are as follows, 01-Jan-2017 00:00:00, 01-Jan-2017 01:00:00, 01-Jan-2017 02:00:00.
I would like to find the index of every Monday(at 00:00:00) present in the data set . Below is what I have used, this is not feasable as I would need to know the exact date of every Monday, type it out row by row and save it to my matrix m.
m=zeros(52,1)
m(1)=find(datetime=='02-Oct-2017 00:00:00')
m(2)=find(datetime=='09-Oct-2017 00:00:00')
...
m(52)=find(datetime=='25-Dec-2017 00:00:00')
Is there a better way to do this?
What I am trying to achieve with this is to create new arrays that start on a Monday and last for a whole week, and do this for the span of a whole year.
I tried to use
[week,edges]=discretize(dt,"week")
but it does not start on a Monday, so I was not able to get it to work.
Thank you
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Accepted Answer
Stephen23
on 10 Dec 2022
You are working with datetimes, so do not compare text!
dt = datetime(2017,1,1,(0:1:123).',0,0, 'Format','u MM dd eee HHmmss')
ix = timeofday(dt)==0 & weekday(dt)==2
md = dt(ix)
2 Comments
Stephen23
on 10 Dec 2022
"What I am trying to achieve with this is to create new arrays that start on a Monday and last for a whole week, and do this for the span of a whole year."
I would have answerd that, but your explanation is incomplete. It sounds as if you want to split your data into lots of separate arrays, but doing so is
- not a good use of MATLAB,
- means that you cannot use the inbuilt mehods for grouping and processing groups of data:
Instead of asking us about how to split data into lots of arrays, you should actaully ask us about your actual goal or task with that data:
More Answers (1)
Arif Hoq
on 10 Dec 2022
I don't have your data. try this one:
% creating datetime data from 1st January 2017 to 31 December 2017
firstdate = '01-01-2017 00:00:00';
t1 = datetime(firstdate,'InputFormat','dd-MM-yyyy HH:mm:ss');
lastdate='31-12-2017 23:00:00';
t2 = datetime(lastdate,'InputFormat','dd-MM-yyyy HH:mm:ss');
oneyeardata=t1:+hours(1):t2;
realdate=oneyeardata(:);
dayname=day(realdate,'name');
strname=string(dayname);
dateday=table(realdate,strname);
findmonday=find(strcmp(string(table2cell(dateday(:,2))),"Monday"));
idxmonday=dateday(findmonday,1);
aa=string(table2cell(idxmonday));
bb=split(aa," ");
cc=find(strcmp(bb(:,2),'00:00:00'));
Monday_Only=idxmonday(cc,1);
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