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ncreadatt

Read attribute from netCDF data source

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    Syntax

    attvalue = ncreadatt(source,location,attname)

    Description

    attvalue = ncreadatt(source,location,attname) reads the netCDF attribute attname from the group or variable specified by location in source. The returned attribute value is of the MATLAB® data type that best matches the netCDF data type of attname. For more information about how MATLAB determines the best match, see NetCDF to MATLAB Data Type Conversion.

    example

    Examples

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    Open Live Script

    Read the creation_date global attribute of the netCDF file example.nc.

    creationDate = ncreadatt("example.nc","/","creation_date")
    creationDate = 
'29-Mar-2010'
    Open Live Script

    Read the scale_factor attribute associated with the temperature variable.

    scaleFactor = ncreadatt("example.nc","temperature","scale_factor")
    scaleFactor = 
1.8000
    Open Live Script

    Read the description attribute associated with the /grid2 group. You can read group attributes from files with format netcdf4 only.

    groupDescription = ncreadatt("example.nc","/grid2","description")
    groupDescription = 
'This is another group attribute.'

    Input Arguments

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    Name of the netCDF data source, specified as a string scalar or character vector. The source argument can be one of these values:

    • The path of a local netCDF source

    • The OPeNDAP URL of a remote OPeNDAP netCDF data source

    • The HTTP URL of a remote netCDF source, with #mode=bytes appended to the end of the URL to enable byte-range reading

      Note

      Byte-range reading is slower than other methods for reading from remote sources. For more details about byte-range reading, see the netCDF documentation.

    Example: "myNetCDFfile.nc"

    Example: "http://host_name/netcdf_filename#mode=bytes"

    Location of a variable or group in the netCDF data source, specified as a string scalar or character vector. To read a global attribute, set location to "/" (forward slash).

    Example: "myVar"

    Example: "/myGrp/mySubGrp/myNestedVar"

    Example: "myGrp"

    Example: "/myGrp/mySubGrp"

    Attribute name to be read, specified as a string scalar or character vector.

    Example: "myAttribute"

    More About

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    NetCDF to MATLAB Data Type Conversion

    The netCDF-related MATLAB functions automatically choose the MATLAB data type that best matches the netCDF data type according to this table.

    NetCDF Data TypeMATLAB Data Type
    NC_DOUBLEdouble
    NC_FLOATsingle
    NC_INTint32
    NC_SHORTint16
    NC_BYTEint8
    NC_CHARchar
    NC_STRING (*)string
    NC_INT64 (*)int64
    NC_UINT64 (*)uint64
    NC_UINT (*)uint32
    NC_USHORT (*)uint16
    NC_UBYTE (*)uint8
    User-defined NC_VLEN types (*)cell

    (*) These netCDF data types are available only for files with format netcdf4.

    Tips

    • The ncreadatt function returns attributes that are vectors as row vectors.

    Version History

    Introduced in R2011a

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    See Also

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