How to take mean of rows of particular value?

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Keegan Carvalho 2020-4-26

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评论： darova 2020-4-27

temp.xlsx

I have an excel file with three columns (Year, Month, Temp). I wanted to find the monthly mean of Temp values from 1997 to 2019 i.e. Jan-97, Feb-97 and so on...

Now, the table (file atteached) has many values for Month 1, Month 2, etc. This is because I have extracted values from different grid points and hence is a little messy. It looks like this:

I used the sortrows function to order the table. However, I do not know how to proceed further. My main aim is to sort the data with respect to Month (Jan-1997, Feb-1997 ... Dec-2019) and then calculate the monthly mean of Temp values from Jan-1997 to Dec-2019. Looking forward to your assistance

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darova 2020-4-26

Everything looks correct. Sortred by rows. What is wrong?

Use mean to calculate mean value

Keegan Carvalho 2020-4-26

编辑：Keegan Carvalho 2020-4-26

If you sort the data, there are many 1997s (Year) 1s (Months):

So how would I group (take mean) all of the TEMP values for the Year 1997 and Month 1 and similarly Month 2 and so on? I am thinking maybe to loop the columns but not sure how to go about it.

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darova 2020-4-26

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Sort your data and use for loop

schematic code (not tested)

s = 0;                  % sum of group data
k = 1;                  % index of group start
for i = 1:n-1
    s = s + a(i);
    if a(i) ~= a(i+1)
        a1(k:i) = s/(i-k+1);    % write mean inside a1
        s = 0;                  % zeros sum
        k = i;                  % new group start
    end
end