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How to extract certain time in matrix data

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Nurul Ain Basirah Zakaria 2020-10-29

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评论： Nurul Ain Basirah Zakaria 2020-11-1

Hi.

I have a 476x160x140 precipittaion data (precip/time,lon,lat), from 1981 to 2011 in nc file. Can I extract certain data for a certain year and time? Its like selyear in CDO but I need to do it in Matlab.

Thank you in advance!

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Nurul Ain Basirah Zakaria 2020-10-29

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sory the file is in mat file.

Walter Roberson 2020-10-29

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It is not obvious how the 476 precip/time is layed out? Is it like 4 hours a day measured for 17 selected weeks a year??

Nurul Ain Basirah Zakaria 2020-10-29

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For 1981-2011, and each year for 12 months. Its monthly data for 30 years sir.

per isakson 2020-10-29

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编辑：per isakson 2020-10-29

Maybe NetCDF/GRIB reader or some other submission to of File Exchange could be useful. The summary includes this paragraph

Technically speaking, MATLAB-CDI consists of mex-interfaces to the CDI library that read GRIB/netCDF. CDI is the basic library underlying the famous CDO (Climate Data Operators) developed by Max-Planck Institut für Meteorologie in Hamburg. The MATLAB-CDI interface package has been developed by The MathWorks Consulting on behalf of the Rossby Centre, SMHI.

Walter Roberson 2020-10-29

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30 years, 12 months per year, gives 360 entries. You have 116 extra entries. Even if your 1981-2011 is 31 years, that would still be an extra 476-12*31 = 104 entries.

Nurul Ain Basirah Zakaria 2020-10-29

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oh yes sir. total time(precip)xlonxlat is 372x160x140.

Walter Roberson 2020-10-29

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在 MATLAB Online 中打开

So row index is (year - 1981)*12+month ?

If you were to

data4 = reshape(YourData, [], 12, size(YourData,2), size(YourData,3));

then rows would correspond to years, and dimension 2 would correspond to months, and dimension 3 would correspond to lon, and dimension 4 would correspond to lat. That might make it easier to do month-by-month comparisons across years.

Nurul Ain Basirah Zakaria 2020-10-29