how to sum data every year

hello

i have a 11322x6 double. i have the date in the first column, months and days in the third and the forth. on the fivth and the sixth colum i have the variables. temperature and degre days that i calculeted from temperature. now i need to sum every degre day of every year together , the problem years change the number evey 4 years so how to do it with a function or easy loop. i saw a lot of them on matlab but don't kenw how to use itnd i don't knew to apply it on my case

Answer 1

[Adam Danz]

No loop needed.

Use findgroups() on the appropriate column(s) to group the rows. Then use

mu = splitapply(@mean, data, groups)

to compute the mean of each group where data is the temperature column.

If your data contain missing values, you can use mu = splitapply(@(x), mean(data,'omitnan'), groups).

Let us know if you get stuck.

[Hichem Younsi]

so i can't apply the findgroups in an array ?

[Adam Danz]

Updated comment

You can't apply findgroups to a matrix but you can find unique rows of a table

[G,TID] = findgroups(T)

or you can separate the columns of your matrix and use this syntax

G = findgroups(A1,...,AN)

Both of those links will show documentation that describes the syntax and provides examples.

Answer 2

[Hichem Younsi]

oof that worked thank you Adam Danz. i convert the matrix to an table and then i used the findgroups to find how many days in each mounths in years and then i used the splitapply function to sum the variable on folwngs years. GREAT THANK YOU

Adam Danz

[Adam Danz]

High five!