time series 30 year sliding window

Question

James 2011-10-2

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https://ww2.mathworks.cn/matlabcentral/answers/17294-time-series-30-year-sliding-window

I have a set of daily data that ranges from the years 1772-2009. The data is currently in an array that has one column as the date number and one column as my data. I want to set 30 year sliding windows for this data moving a year on every time. For example I want the data to be in an array where the first column has all the data from 1772-1801, the 2nd has all the data from 1773-1802 and so on.

Each value has a corresponding date to it (year, month and day). It would be nice to be able to program MATLAB to take all the values corresponding to the years in the ranges I need.

For example I want to say something along these lines, I just dont know the exact code or if what I want to do is even possible: I already have data = my daily data

for y=1772:1979

30yearperiods(:,1,2,3...207) = temp (dependent on year== n to n+30)

Does anyone know how I can do this?

I have had major problems trying to set for loops that encompass the 30 year periods including all the leap years etc and its frustrating having to do this when I have the data I need and I just can't extreact it

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Answer 1

Fangjun Jiang 2011-10-2

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https://ww2.mathworks.cn/matlabcentral/answers/17294-time-series-30-year-sliding-window#answer_23327

在 MATLAB Online 中打开

Since not all 30-year periods contain the same number of dates (due to leap year), you'll need to use cell array to have the 30-year moving window data. It's a matter of utilizing the datenum() function.

clear;
%create an example data
StartYear=1772;
EndYear=2009;
OrigData=datenum(StartYear,1,1):(datenum(EndYear,1,1)-1);
OrigData=[OrigData',(1:length(OrigData))'];
%constrct the desired data
Period=30;
Data=cell(EndYear-StartYear-Period+1,1);
for Year=StartYear:(EndYear-Period)
    StartCount=datenum(Year,1,1)-datenum(StartYear,1,1)+1;
    DataCount=datenum(Year+Period,1,1)-datenum(Year,1,1);
    Data{Year-StartYear+1}=OrigData(StartCount:(StartCount+DataCount-1),2);
end
>> OrigData(end,:)
ans =
        733773       86563
>> Data{end}(end)
ans =
         86563

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James 2011-10-3

Like I need a list of the values in the array so I can detrend, take the mean etc?

Fangjun Jiang 2011-10-3

To reference the 2nd data in your first 30-year period, use Data{1}(2),

100th data in the 3rd 30-year period, Data{3}(100).

Your original data has two columns, right? The first column is just date, the second column is your true data, temperature, for example. I just use a serial of numbers to mimic the second column data.

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