DATE LOOPS AND DATE TRATEMENT IN MATLAB

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André Bernal García
编辑： André Bernal García 2017-3-28
Im working with quite a lot of data and I want to use it in a Matlab code.
The data is identified for a certain time and and hour with a certain timestamp ( given as a number)
I want to create loops that are using the DATA especified for that certain timestamp.
I was trying to do so by generating a datetime array in matlab, as the following picture shows:
But when I am trying to do a loop such as:
for i=TIMED(1):TIMED(8774) X= UP(i)/1000 Y=Eoffered (i)*UP(i)
I have the following error:
Function 'subsindex' is not defined for values of class 'datetime'.
Error in ASS2 (line 15) Pelspot(TIMED)=ELSPOT(TIMED)/1000; % €/ kW
PS: I will have to use a lot of data and it is not always in order ( some values are repeated) so I want to get sure that only the values with that timestamp are used.
Thanks in advance !! =)
I have the data in an excel file, I dont know how to create a database but maybe is useful.

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回答（1 个）

Steven Lord
Steven Lord 2017-3-28
What is the "December 31st, 2015 at 10 AM"-th element of the vector [15.86; 17.79; 18; 18.84; 19; ...]? Does that question even make sense?
If you're using release R2016b or later, store your data in a timetable. Since dates and times are an integral part of a timetable, you can index into a timetable using dates and times.
  1 个评论
André Bernal García
André Bernal García 2017-3-28
编辑：André Bernal García 2017-3-28
Maybe I wrote my question wrong:
I have the data like this in Excel:
--------------------------------------------------
Where the timestamp(number) represents yyyymmddHHMM
To transform the timestamp to date I created an arrow just with the timestamp and I did:
%TIME is the vector in column with the timestamps
str = num2str(TIME, '%11d');
dn = datenum(str, 'yyyymmddHHMM');
ds = datestr(dn, 'yyyy-mm-dd HH:MM') % ‘Legacy’ Functions
dt = datetime(str, 'InputFormat','yyyyMMddHHmm', 'Format','yyyy-MM-dd HH:mm') % ‘datetime’ Function
Now, as you told me I am trying to create a timetable but: - If I use the excel table directly then it does not recognizes time.
-I have not been able to change the first column to a "date" column and therefore the timetable comand does not accept it as a timecolumn and it does not work

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