MATLAB: How to find average monthly wind velocity values for given years

annualMATLABmonthlywind velocity

I am new to MatLab and trying to create an average monthly wind velocity array for three separate years (2017-19), which I can then plot against each other and finally calculate the accumulated monthly mean from 2017-19.
This is the table formatting
How would I separate each year and determine the monthly mean wind velocities, which I can then insert into a line chart such as this (below) showing each year?

Best Answer

Use groupsummary to compute the means for 12 months across all days/years.
Demo:
T = table((1:10)', randi(12,10,1), 2017.*ones(10,1), randi(20,10,1)+200, rand(10,1)*20, ...
    'VariableNames', {'Day','Month','Year','WindDirection','WindSpeed'})
T = 10x5 table
    Day    Month    Year    WindDirection    WindSpeed
    ___    _____    ____    _____________    _________

     1       8      2017         210          16.225  
     2       4      2017         202          18.072  
     3       6      2017         208          18.326  
     4       5      2017         215          12.933  
     5       1      2017         220          10.287  
     6      10      2017         204          2.1927  
     7       8      2017         205          4.0338  
     8       6      2017         219          11.377  
     9       2      2017         202          1.3805  
    10       8      2017         206          8.2965  

groupsummary(T,'Month','mean',{'WindDirection','WindSpeed'})
ans = 7x4 table
    Month    GroupCount    mean_WindDirection    mean_WindSpeed
    _____    __________    __________________    ______________

      1          1                 220               10.287    
      2          1                 202               1.3805    
      4          1                 202               18.072    
      5          1                 215               12.933    
      6          2               213.5               14.851    
      8          3                 207               9.5186    
     10          1                 204               2.1927
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