ncreadatt - Read attribute from netCDF data source - MATLAB (original) (raw)

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Read attribute from netCDF data source

Syntax

Description

`attvalue` = ncreadatt([source](#mw%5F541d6a5c-1c73-4301-a9a9-047dbbe46b2f%5Fsep%5Fmw%5Fe339e1a9-285c-4606-9ca3-5d590980a4d2),[location](#mw%5Ff1c4179d-52c1-4dd3-afe2-ca60cd0dd175),[attname](#mw%5Feaf8bc1e-33fa-416c-9c5a-4e505c65c6e2)) 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 ofattname. For more information about how MATLAB determines the best match, see NetCDF to MATLAB Data Type Conversion.

example

Examples

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

creationDate = ncreadatt("example.nc","/","creation_date")

creationDate = '29-Mar-2010'

Read the scale_factor attribute associated with the temperature variable.

scaleFactor = ncreadatt("example.nc","temperature","scale_factor")

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. Thesource 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://_`hostname`_/_`netcdffilename`_#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, setlocation 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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The netCDF-related MATLAB functions automatically choose the MATLAB data type that best matches the netCDF data type according to this table.

(*) These netCDF data types are available only for files with formatnetcdf4.

Tips

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

Version History

Introduced in R2011a

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You can use ncreadatt for read-only access to remote datasets using the HTTP byte-range capability, provided that the remote server supports byte-range access.

You can read variable length array data types (NC_VLEN) from netCDF-4 files.

You can read NC_STRING attributes from netCDF-4 files.