Best tool for analysing/altering netcdf data (beyond read-only)

조회 수: 3 (최근 30일)
mashtine . 2015년 6월 17일
답변: hafez ahmad . 2020년 1월 16일
I have a large netcdf file that I would like to do some processing on. CDO software is not adequate enough and I need to resort to using matlab. I can access the data easily with the 'ncread' commands etc but I would like to know how to apply an analysis (say, an equation using a few varibles of the dataset) on the netcdf file using matlab. For instance, can I use matlab to create a new variable in the netcdf file? I have seen the NCToolBox add on for Matlab but this is read-only.
I have a netcdf file with about 10 climate variables and I would like to implement a scheme to calculate a new variable directly within the netcdf. I can use ncread to read in the data but then I am not too sure how I keep other attributes such as time when performing the calculations. My scheme will involve a few steps as well as boolean analysis, so I am a bit confused there.
Thank you!
Hope I explained that well enough,

답변 (3개)

Ashish Uthama
Ashish Uthama 2015년 6월 17일
There are more functions in the ncread family - Have a look at all of them here.
Look at ncwrite for write capability, the documentation has some examples to help you get started.
Once you get the data into MATLAB using ncread, then you can leverage any of MATLAB's analysis functionality on it (its just numbers to MATLAB at this point).
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mashtine 2015년 6월 17일
Thanks Ashish,
I believe my interpretation of how matlab handles the netcdf file was different, hence the brevity in my question but I think I understand what you mean now. I guess my question stemmed from being able to retain the timestamps (1980-01-01 00:00:10 etc) while doing the calculations but I think that this can be done with ncread as well and stored separately if I am not mistaken.
Thank you

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Chad Greene
Chad Greene 2015년 6월 17일
I'm not sure what the problem is. NetCDF files contain matrices, which are well suited for Matlab (MatrixLaboratory). To get a variable like sea surface temperature,
sst = ncread('','sst');
Then you can do whatever analysis you want on the sst matrix. After you've used ncread the analysis part of your question has nothing to do with the fact that the matrix originally came from a NetCDF file. When you're satisfied with your analysis, use ncwrite to write a NetCDF file with whatever variables you'd like.
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mashtine 2015년 6월 17일
Thanks Chad,
As mentioned in my comment above, I was not too sure how to retain the timestamp associated with the variables in the netcdf file while carrying out my calculations if that makes any sense. I think I have a clearer picture now and perhaps I thought it needed to be more complex than it really is.
Thanks again,

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hafez ahmad
hafez ahmad 2020년 1월 16일
I did in the following way.
NETCDF_File1='C:/Users/hafez/personal/GIS DATA/winds/'
ncid1 =,'NC_NOWRITE');
lon= netcdf.getVar(ncid1,3);
lat= netcdf.getVar(ncid1,2);


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