MATLAB: Calculate longterm daily average

Question

I manged to do monthly average like this.

mat = randi([0 14600], 730, 5, 2);
sc1 = (datetime(1981,1,1):datetime(1982,12,31))';
splitmat = num2cell(permute(mat, [1 3 2]), [1 2]); 
TT1 = timetable(sc1,splitmat{:});
monthlyaverage = retime(TT1, 'monthly', 'mean');

If I do

monthlyaverage = retime(TT1, 'daily', 'mean'); 

it will return the same value as the data is daily. However, I am interested to get longterm daily average that means average of day of the year (day 1 … day 365). The final answer number of rows will be only 365. is there similar approach that is concise like retime to do it?

thanks

Answer 1

Create timetable (from OP's code)

mat = randi([0 14600], 730, 5, 2);
sc1 = (datetime(1981,1,1):datetime(1982,12,31))';
splitmat = num2cell(permute(mat, [1 3 2]), [1 2]); 
TT1 = timetable(sc1,splitmat{:});

Compute averages for day-of-year using grpstats().

% List all data columns
varList = TT1.Properties.VariableNames(2:end); 
% Compute day-of-year and add it to the table
TT1.DOY = day(TT1.sc1, 'dayofyear');
% Compute mean for each day-of-year
% This requires converting the TimeTable to a Table
% This also requires Stats & Machine Learning Toolbox
dailyAvg = grpstats(timetable2table(TT1(:,2:end)),'DOY','mean','DataVars',varList)

First few rows of output

head(dailyAvg)
        DOY    GroupCount       mean_Var2           mean_Var3           mean_Var4           mean_Var5    
         ___    __________    ________________    ________________    ________________    ________________
    1     1         2           6272    2320.5    9136.5     10590    5050.5     10498    8312.5      9643
    2     2         2          12622     987.5      6968      4419      2484    7055.5     11215    9381.5
    3     3         2           6032      1531      3696    1633.5     11304      8133     10159      7516
    4     4         2           9188      1711      1905      7979     10044      3948      7382      6632
    5     5         2           8311     10974      9007     11422      7507    3849.5      3333    6290.5
    6     6         2          14211    4030.5     10858    4806.5      8750      7859      4807      3746
    7     7         2         9090.5      5260    5890.5      9528     11296    4518.5    7327.5     10649
    8     8         2         7022.5     11904      3766     12161     12543    8624.5      5090     10506