mean seasonal data

Question

niclo 2012-2-23

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评论： Robert 2018-5-23

Hello,everyone. I have a seasonal data set which is 123 x 21 x 23 double. the data is arrange in this way :1st is dec 1959, second is jan 1960, third is feb 1960,forth is dec 1960, fifth is jan 1961 and until feb 2000. I need to mean the DJF of every year so that i will have only 1 value for each year. At the end, i will want to hv only 1 row which the 1st is mean value of DJF1960, 2nd is mean value of DJF1961. Can anyone help me to solve this problem? Thank you.

if I had to do this manualy it probably look like this:

a(1,:)=mean(mean(unnamed(1:3)));

b(1,:)=mean(mean(unnamed(4:6))); . .

n(1,:)=mean(mean(unnamed(120:123)));

all=[a;b;c.....n];

But Of cousre I cannot do it manually because it will probably take the rest of my life! and i have many other set of data. So how can I replicate this for a huge dataset? Can anyone teach me how to write a loop so that i don't have to repeat my work until 123 times?

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Oleg Komarov 2012-2-23

It's not clear how your data is organized.

row 1-3 = data for Dec 1960 - Feb 1961 and so on

What's in column 1,2 etc

And why fo you have 23 layers (3rd dimension)?

niclo 2012-2-24

My data is arranged in this way:

dec 1959

jan 1960

feb 1960

mar 1960

apr 1960

may 1960

jun 1960

jul 1960

aug 1960

sep 1960

oct 1960

nov 1960

dec 1960

jan 1961

.

.nov 2000

So i would like to extract the DJF for every year, so that my data will become like this:

dec 1959

jan 1960

feb 1960

dec 1960

jan 1961

feb 1961

..

After that, i need to mean the DJF for every year. So at the end my data will become 1 x 41 (because i have 41 years).

My original data is 123 x 21 x 23, the 21 is latitude and 23 is longitude.

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Answer 1

Bjorn Gustavsson 2012-2-23

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在 MATLAB Online 中打开

QD:

idxDJF = sort([[1:12:123],[2:12:123],[3:12:123]]);
Wacc = cumsum(unnamed(idxDJF,:,:));
Wavg = Wacc(3:3:end,:,:)/3;

Will leave you with a Wavg with size: 11 x 21 x 23.

HTH

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Answer 2

Danhay 2016-2-22

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I am answering this in case someone else is having a similar problem. I have a matlab script to handle this problem for both 2D and 3D data: http://dans7messiah.thoughts.com/posts/calculating-the-mean-for-a-selected-period-to-create-a-time-series-of-mean-matlab

Cheers, Daniel

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saida ghrab 2017-5-18

Hello Danhay, I have the same problem but I couldn't download the script can you please check the link. Thank you so much

Robert 2018-5-23

Hi Danhay, would be possible to have the latest link to your script? Links provided are not working.

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