SOLVED - Slip a single array in three unequal parts, three years observation with a leap year in between

Hello everybody,

I am very new to matlab and I need all your help:

I have this array 26304 x 1 that are hourly observations of sst over three years: i need to split this array in three arrays corresponding to year 2014, 2015 and 2016. I can't split the array in equal parts since year 2016 is a leap year.

I will then compute the monthly mean for each months in each year and merge the data together again, in order to have a single array 1096x1.

Thank you very much!

[Cris LaPierre]

Not sure how monthly data for 3 years gives you 1096. Wouldn't 12 months x 3 years = 36 rows of data? Did you mean daily instead of monthly?

[CARLOTTA DENTICO]

Sure, I meant monthly (so at the end I will have 1 x 36) but when I wrote it I made the calculation considering daily data!

Answer 1

[Cris LaPierre]

I would look into timetables and groupsummary. With a timetable, you can add a date and time to each row, and then with groupsummary, you can group your data by year and month, and compute the mean of each group.

data = rand(26304,1);
dataTT = timetable(data,'TimeStep',hours(1),'StartTime',datetime(2014,1,1))

dataTT = 26304×1 timetable
            Time              data  
    ____________________    ________

    01-Jan-2014 00:00:00    0.083863
    01-Jan-2014 01:00:00     0.72604
    01-Jan-2014 02:00:00     0.26453
    01-Jan-2014 03:00:00     0.63959
    01-Jan-2014 04:00:00     0.46283
    01-Jan-2014 05:00:00     0.60372
    01-Jan-2014 06:00:00     0.53723
    01-Jan-2014 07:00:00      0.5202
    01-Jan-2014 08:00:00     0.56378
    01-Jan-2014 09:00:00     0.76735
    01-Jan-2014 10:00:00     0.97978
    01-Jan-2014 11:00:00     0.03396
    01-Jan-2014 12:00:00     0.08551
    01-Jan-2014 13:00:00     0.15598
    01-Jan-2014 14:00:00     0.49928
    01-Jan-2014 15:00:00      0.6527

avgT = groupsummary(dataTT,"Time","month","mean")

avgT = 36×3 table
    month_Time    GroupCount    mean_data
    __________    __________    _________

     Jan-2014        744         0.48536 
     Feb-2014        672         0.49625 
     Mar-2014        744         0.50871 
     Apr-2014        720         0.49382 
     May-2014        744         0.52113 
     Jun-2014        720         0.50644 
     Jul-2014        744         0.50069 
     Aug-2014        744         0.48957 
     Sep-2014        720         0.48952 
     Oct-2014        744         0.49456 
     Nov-2014        720         0.50474 
     Dec-2014        744         0.50123 
     Jan-2015        744          0.5092 
     Feb-2015        672         0.50245 
     Mar-2015        744         0.49252 
     Apr-2015        720         0.51885 

[CARLOTTA DENTICO]

Precious help!! Exactly what I needed!