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ncread

Read data from variable in NetCDF data source

Syntax

vardata = ncread(source,varname)
vardata = ncread(source,varname,start,count,stride)

Description

vardata = ncread(source,varname) reads data from the variable varname in source, which can be either the name of a NetCDF file or an OPeNDAP NetCDF data source.

vardata = ncread(source,varname,start,count,stride) reads data from the variable varname in source beginning at the location given by start. count specifies the number of elements to read along the corresponding dimension. The optional argument stride specifies the inter-element spacing along each dimension.

Input Arguments

source

Text string specifying the name of a NetCDF file or the URL of an OPeNDAP NetCDF data source.

varname

Text string specifying the name of a variable in the NetCDF file or OPeNDAP NetCDF data source.

start

For an N-dimensional variable, start is a vector of length N of indices specifying the starting location. Indices are 1-based.

count

Vector of length N specifying the number of elements to read along the corresponding dimensions. If a particular element of count is Inf, ncread reads data until the end of the corresponding dimension.

stride

Optional argument that specifies the inter-element spacing along each dimension.

Default: Vector of 1s (ones)

Output Arguments

vardata

The data in the variable. ncread uses the MATLAB® datatype that is the closest type to the corresponding NetCDF datatype, except when at least one of _FillValue, scale_offset, and add_offset variables attribute is present. ncread applies the following attribute conventions, in sequence, to vardata if the corresponding attribute exists for this variable:

  • If the _FillValue attribute exists, ncread replaces values in vardata equal to the value of _FillValue with NaNs. If the_FillValue attribute does not exist, ncread queries the NetCDF library for the variable's fill value.

  • If the scale_factor attribute exists, ncread multiplies vardata by the value of the scale_factor attribute.

  • If the add_offset attribute exists, ncread adds the value of the add_offset attribute to vardata.

Examples

Read and display the data in the peaks variable in the example file.

ncdisp('example.nc','peaks');
peaksData  = ncread('example.nc','peaks');
peaksDesc  = ncreadatt('example.nc','peaks','description');
surf(double(peaksData));
title(peaksDesc);
 

Subsample the peaks data by a factor of 2 (read every other value along each dimension).

subsetdata = ncread('example.nc','peaks',...
                    [1 1], [Inf Inf], [2 2]);
surf(double(subsetdata));

See Also

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Tutorials

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