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How to extract the data from .nc file based on longitude and latitude,time?

Asked by alagu mathi on 17 May 2014
Latest activity Commented on by Jonas Damsbo on 27 Dec 2018
Hi, I have to extract the data from netcdf file based on lat,long and time. I have written the following code.
ncid = netcdf.open('\C:\Users\divecha21\Desktop\errorBar\tasmax_day_BNU-ESM_rcp85_r1i1p1_20060101-21001231.nc','NC_NOWRITE');
peaksData = ncinfo('\C:\Users\divecha21\Desktop\errorBar\tasmax_day_BNU-ESM_rcp85_r1i1p1_20060101-21001231.nc','tasmax');
ncdisp('\C:\Users\divecha21\Desktop\errorBar\tasmax_day_BNU-ESM_rcp85_r1i1p1_20060101-21001231.nc','tasmax');
[ndim, nvar, natt, unlim] = netcdf.inq(ncid)
[dimname, dimlength] = netcdf.inqDim(ncid, 0)
[dimname, dimlength] = netcdf.inqDim(ncid, 1)
[dimname, dimlength] = netcdf.inqDim(ncid, 2)
lon = netcdf.getVar(ncid,0,0,128)
%time = netcdf.getVar(ncid,2,0,34675)
lat = netcdf.getVar(ncid,1,0,64)
latlim = [5.25 36.75];
lonlim = [60.25 97.25];
precJanuary = netcdf.getVar(ncid,2,[60.25 5.25 1],[97.25 36.75 1]);
Actually I have global temperature data i have to extract only india. After execution,I got the following error.
>> sample1
Error using ncread Expected start to be integer-valued.
Error in internal.matlab.imagesci.nc/read (line 557) validateattributes(start,{'numeric'},...
Error in ncread (line 58) vardata = ncObj.read(varName, varargin{:});
Error in sample1 (line 27) precJanuary = ncread('\C:\Users\divecha21\Desktop\errorBar\tasmax_day_GFDL-ESM2M_rcp85_r1i1p1_20060101-20101231.nc','tasmax',[60.25 5.25 1],[97.25 36.75 1]);
Can any one help me to clear this? I am new to matlab.
Thank you

  5 Comments

Did you try using NCREAD itself? (NCINFO will give you dimension info about a variable).
Yes,I tried ncinfo() but still i could n't clear that problem.
will you please write the revised code for extracting nc files, I am looking for the data for India...

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1 Answer

Answer by Ashish Uthama on 20 May 2014
Edited by Ashish Uthama on 20 May 2014
 Accepted Answer

The nc* functions and the netcdf.* functions represent two independent ways to access a NetCDF file. I would recommend sticking to nc* functions until you get comfortable enough to directly access the NetCDF library interface using the netcdf.* functions (it uses C style indexing and dimension ordering which is different from what nc* functions report and use).
Instead of
precJanuary = netcdf.getVar(ncid,2,[0 0 0],[128 64 1]);
try
precJanuary = ncread(filename, varname,[1 1 1],[128 64 1]);

  2 Comments

Thank you @Ashish Uthama.Yes i have edited the code as per your suggestion.I have south_india.fig(like shape file)i have to extract the data only that region.
I try to use your code line:
z = ncread(ncfiles(i).name,'z',[1 1 1],[360 181 1]);
But I got the error:
Index exceeds array bounds. Why?

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