MATLAB Function Reference

cdfinfo

Return information about a CDF file

Syntax

• info = cdfinfo(file)
  

Description

info = cdfinfo(file) returns information about the Common Data Format (CDF) file specified in the string, file. The function returns a structure, info, that contains the fields shown in the following table.

Field	Description	Return Type
FileModDate	Date the file was last modified	String
Filename	Name of the file	String
FileSettings	Library settings used to create the file	Structure array
FileSize	Size of the file, in bytes	Double
Format	File format (CDF)	String
FormatVersion	Version of the CDF library used to create the file	String
GlobalAttributes	Global metadata	Structure array
Subfiles	Filenames containing the CDF file's data, if it is a multifile CDF	Cell array
VariableAttributes	Metadata for the variables	Structure array
Variables	Details about the variables in the file	Cell array

The GlobalAttributes and VariableAttributes Fields

GlobalAttributes and VariableAttributes are structure arrays that each contain one field for each global or variable attribute respectively. The name of the field corresponds to the name of an attribute. The data in that field, contained in a cell array, represents the entry values for that attribute.

For VariableAttributes, the attribute data resides in an N-by-2 cell array, where N is the number of variables. The first column of this cell array contains the variable names associated with the entries. The second column contains the entry values.

Note    Attribute names may not match the names of the attributes in the CDF file exactly. Because attribute names can contain characters that are illegal in MATLAB field names, they may be translated into legal field names. Illegal characters that appear at the beginning of attributes are removed; other illegal characters are replaced with underscores ('_'). If an attribute's name is modified, the attribute's internal number is appended to the end of the field name. For example, Variable%Attribute might become Variable_Attribute_013.

The Variables Field

The Variables field of the returned info structure is an N-by-6 cell array, where N is the number of variables. The six columns of the cell array contain the following information.

Column No.	Description	Return Type
1	Name of the variable	String
2	Dimensions of the variable, as returned by the size function	Double array
3	Number of records assigned for the variable	Double
4	Data type of the variable, as stored in the CDF file	String
5	Record and dimension variance settings for the variable. The single T or F to the left of the slash designates whether values vary by record. The zero or more T or F letters to the right of the slash designate whether values vary at each dimension. Here are some examples. T/ (scalar variable) F/T (one-dimensional variable) T/TFF (three-dimensional variable)	String
6	Sparsity of the variable's records. This is a string holding one of three possible values: 'Full' 'Sparse (padded)' 'Sparse (nearest)'	String

Examples

• info = cdfinfo('example.cdf')
  info = 
                Filename: 'example.cdf'
             FileModDate: '29-Jun-1995 05:51:58'
                FileSize: 230513
                  Format: 'CDF'
           FormatVersion: '2.4.8'
            FileSettings: [1x1 struct]
                Subfiles: {}
               Variables: {7x6 cell}
        GlobalAttributes: [1x1 struct]
      VariableAttributes: [1x1 struct]
  
  info.Variables
  ans = 
      'L_gse'        [1x2 double]   [   1]   'char'    'F/T'  'Full'
      'Status%C1'    [1x2 double]   [7493]   'uint8'   'T/T'  'Full'
      'B_gse%C1'     [1x2 double]   [7493]   'single'  'T/T'  'Full'
      'B_nsigma%C1'  [1x2 double]   [7493]   'single'  'T/'   'Full'
  

See Also

cdfread

cdfepoch

cdfread