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netcdf.getVar

Read data from NetCDF variable

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Syntax

data = netcdf.getVar(ncid,varid)
data = netcdf.getVar(ncid,varid,start)
data = netcdf.getVar(ncid,varid,start,count)
data = netcdf.getVar(ncid,varid,start,count,stride)
data = netcdf.getVar(___,output_type)

Description

data = netcdf.getVar(ncid,varid) returns data, the value of the variable specified by varid. MATLAB® attempts to match the class of the output data to NetCDF class of the variable.

Note

For variables of type NC_CHAR, the netcdf.getVar function supports reading only of data that contain only ASCII-encoded characters. NetCDF-4 files support writing UTF-8 -encoded characters in variables of type NC_STRING.

ncid is a NetCDF file identifier returned by netcdf.create or netcdf.open.

data = netcdf.getVar(ncid,varid,start) returns a single value starting at the specified index, start.

data = netcdf.getVar(ncid,varid,start,count) returns a contiguous section of a variable. start specifies the starting point and count specifies the amount of data to return.

data = netcdf.getVar(ncid,varid,start,count,stride) returns a subset of a section of a variable. start specifies the starting point, count specifies the extent of the section, and stride specifies which values to return.

data = netcdf.getVar(___,output_type) specifies the data type of the return value data. Specify output_type as one of these values:

  • 'double'

  • 'single'

  • 'int64'

  • 'uint64'

  • 'int32'

  • 'uint32'

  • 'int16'

  • 'uint16'

  • 'int8'

  • 'uint8'

  • 'char'

This function corresponds to several functions in the NetCDF library C API. To use this function, you should be familiar with the NetCDF programming paradigm.

Examples

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Open Live Script

Open the example file, example.nc.

ncid = netcdf.open('example.nc','NC_NOWRITE');

Get the name of the first variable in the file.

varname = netcdf.inqVar(ncid,0)
varname = 
'avagadros_number'

Get variable ID of the first variable, given its name.

varid = netcdf.inqVarID(ncid,varname)
varid = 0

Get the value of the variable. Use the variable ID as the second input to the netcdf.getVar function.

data = netcdf.getVar(ncid,varid)
data = 6.0221e+23

Display the data type of the output value.

whos data
  Name      Size            Bytes  Class     Attributes

  data      1x1                 8  double

Get the value of the avogadros_number variable again, specifying that the output data type should be single.

data = netcdf.getVar(ncid,varid,'single');

Display the data type of the output value.

whos data
  Name      Size            Bytes  Class     Attributes

  data      1x1                 4  single

Close the NetCDF file.

netcdf.close(ncid)

See Also

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