I'm having trouble building the time series for each year separately using loops

I'm having a problem with the year 1965 when I'm using loops to build each year's time series (in hours) separately

my field_day in 1965 year

in 1965 year field_day(i) = 8784

It should be 8760(365*24) but he changed to 8784(366*24) Would like to ask where is the problem, or is there a better way to build a year-by-year time series (in hours)

clear all ; clc ; clf ;
 set(gcf,'color','w')

 %% load data
 filehtm = dir('moving_windown_test.xlsx') ;
              
 for ii = 1 : length(filehtm);
     filehtm(ii).name
     [num,str,xlsdata] = xlsread(filehtm(ii).name) ;    %num數值 str字串
 end

 time = num(:,1) ;
 tide_detrend = num(:,2) ./ 1000 ;
 tide = tide_detrend ; 
 tide_raw = tide_detrend;

 %% set time
 YYYY = fix(time/1000000) ;
 
 MM   = mod(fix(time/10000),100) ;
 DD   = mod(fix(time/100),100) ;
 HH   = mod(time,100) ;
 tt   = datenum(YYYY,MM,DD,HH,0,0) ;
  %% remove outliner
 for  k = 1:1:5
     yyyy(k) = 1960 +k;
 t1 = datenum(  yyyy(k),1,1) : 1/24 : datenum(  yyyy(k)+1,1,1); 
 t1(end)=[];
%% data(依照原始數據不同)
  year = YYYY;
 index = find(year ==  yyyy(k));
  t = tt(index); % movingwindown 時間
Q1(k) = prctile(tide(index), 25) ;
Q3(k) = prctile(tide(index), 75);
IQR(k) = Q3(k) - Q1(k)   ;
upper(k) = Q3(k) + 1.5*IQR(k)
lower(k) = Q1(k) - 1.5*IQR(k)
tide_outline = tide(index);
raw_tide = tide(index);
tide_outline(tide_outline > upper(k) | tide_outline < lower(k)) = nan;

 for j = 1 : length(t1);
     if  (isempty(find(t==t1(j))));
         r_tide(j) = nan ;
     else
         r_tide(j) = tide_outline(find(t==t1(j))) ;
     end 
 end
%% this is my problem 
  for  i = 1 : length(t1) ;
  field_day(i) = (yyyy(k)+(i - 1) * 60 * 60 / 86400/365) ;
  end 
            plot(field_day,r_tide);hold on % rawdata
 end

[Simon Chan]

Seems the number of data for each year are different.

And for year 1965, it is not equals to what you are expected.

T = readtable('https://www.mathworks.com/matlabcentral/answers/uploaded_files/899805/moving_windown_test.xlsx');
T.Var1 = datetime(datenum(string(T.Var1),'yyyyMMddhh'),'ConvertFrom','datenum','Format','yyyyMMddhh');
[yearnum,~,index] = unique(year(T.Var1));
count = zeros(length(yearnum),1);
for k = 1:length(yearnum)
    count(k,1) = length(T.Var1(index==k));
end
table(yearnum,count)

ans = 5×2 table
    yearnum    count
    _______    _____

     1961      8749 
     1962      8739 
     1963      8673 
     1964      8716 
     1965      8683 

[peter huang]

For the variable field_day, I want to create a time series for a full year (in hours), leap year (366*24=8784), and normal year (365*24=8760)

[Simon Chan]

You may use function timeshift to generate:

Tseries = dateshift(datetime(1961,1,1,0,0,0),'start','hour',0:8759);
Tseries(1:5)

ans = 1×5 datetime array
   01-Jan-1961 00:00:00   01-Jan-1961 01:00:00   01-Jan-1961 02:00:00   01-Jan-1961 03:00:00   01-Jan-1961 04:00:00

Tseries(end-4:end)

ans = 1×5 datetime array
   31-Dec-1961 19:00:00   31-Dec-1961 20:00:00   31-Dec-1961 21:00:00   31-Dec-1961 22:00:00   31-Dec-1961 23:00:00

Tseries = dateshift(datetime(1964,1,1,0,0,0),'start','hour',0:8783);
Tseries(1:5)

ans = 1×5 datetime array
   01-Jan-1964 00:00:00   01-Jan-1964 01:00:00   01-Jan-1964 02:00:00   01-Jan-1964 03:00:00   01-Jan-1964 04:00:00

Tseries(end-4:end)

ans = 1×5 datetime array
   31-Dec-1964 19:00:00   31-Dec-1964 20:00:00   31-Dec-1964 21:00:00   31-Dec-1964 22:00:00   31-Dec-1964 23:00:00

Answer 1

[Seth Furman]

I'm not clear on the question being asked, but here's a simpler way to import the data into a timetable.

fname = "https://www.mathworks.com/matlabcentral/answers/uploaded_files/899805/moving_windown_test.xlsx";
opts = detectImportOptions(fname);
opts = setvaropts(opts, 1, "Type", "string");
t = readtable(fname, opts)

t = 43560×2 table
        Var1        Var2
    ____________    ____

    "1961010100"    -456
    "1961010101"    -456
    "1961010102"    -566
    "1961010103"    -656
    "1961010104"    -676
    "1961010105"    -676
    "1961010106"    -616
    "1961010107"    -456
    "1961010108"    -136
    "1961010109"      45
    "1961010110"     105
    "1961010111"     146
    "1961010112"      95
    "1961010113"      25
    "1961010114"     -15
    "1961010115"     -66

t.Var1 = datetime(t.Var1, "InputFormat", "uuuuMMddHH")

t = 43560×2 table
            Var1            Var2
    ____________________    ____

    01-Jan-1961 00:00:00    -456
    01-Jan-1961 01:00:00    -456
    01-Jan-1961 02:00:00    -566
    01-Jan-1961 03:00:00    -656
    01-Jan-1961 04:00:00    -676
    01-Jan-1961 05:00:00    -676
    01-Jan-1961 06:00:00    -616
    01-Jan-1961 07:00:00    -456
    01-Jan-1961 08:00:00    -136
    01-Jan-1961 09:00:00      45
    01-Jan-1961 10:00:00     105
    01-Jan-1961 11:00:00     146
    01-Jan-1961 12:00:00      95
    01-Jan-1961 13:00:00      25
    01-Jan-1961 14:00:00     -15
    01-Jan-1961 15:00:00     -66

tt = table2timetable(t)

tt = 43560×1 timetable
            Var1            Var2
    ____________________    ____

    01-Jan-1961 00:00:00    -456
    01-Jan-1961 01:00:00    -456
    01-Jan-1961 02:00:00    -566
    01-Jan-1961 03:00:00    -656
    01-Jan-1961 04:00:00    -676
    01-Jan-1961 05:00:00    -676
    01-Jan-1961 06:00:00    -616
    01-Jan-1961 07:00:00    -456
    01-Jan-1961 08:00:00    -136
    01-Jan-1961 09:00:00      45
    01-Jan-1961 10:00:00     105
    01-Jan-1961 11:00:00     146
    01-Jan-1961 12:00:00      95
    01-Jan-1961 13:00:00      25
    01-Jan-1961 14:00:00     -15
    01-Jan-1961 15:00:00     -66

unique(dateshift)