CDF Files

Common Data Format

Common Data Format (CDF) is a self-describing data format for the storage of scalar and multidimensional data in a platform- and discipline-independent way. You can interact with CDF files in two ways:

The MATLAB^® high-level CDF functions provide a simplified programmatic interface for reading data from CDF files.
The MATLAB low-level CDF functions provide finer control over the reading and writing process of CDF files by providing access to more than 90 functions in the CDF C library. To export data to a CDF file, you must use the low-level functions. To use these functions in MATLAB, prefix the function name with the cdflib namespace path. For example:
```
cdfid = cdflib.open("example.cdf");
```
To use the MATLAB low-level CDF functions, you must be familiar with CDF C API programming concepts, described at https://cdf.gsfc.nasa.gov/.

MATLAB uses CDF C library version 3.8.1.

Functions

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High-Level Functions for CDF Files

`cdfinfo`	Information about Common Data Format (CDF) file
`cdfread`	Read data from Common Data Format (CDF) file

Low-Level Functions for CDF Files

Library Information

`cdflib.getConstantNames`	Names of Common Data Format (CDF) library constants
`cdflib.getConstantValue`	Numeric value corresponding to Common Data Format (CDF) library constant
`cdflib.getFileBackward`	Return backward compatibility mode
`cdflib.getLibraryCopyright`	Copyright notice of Common Data Format (CDF) library
`cdflib.getLibraryVersion`	Library version and release information
`cdflib.getValidate`	Library validation mode
`cdflib.setFileBackward`	Specify backward compatibility mode
`cdflib.setValidate`	Specify library validation mode

File Operations

`cdflib.close`	Close Common Data Format (CDF) file
`cdflib.delete`	Delete Common Data Format (CDF) file
`cdflib.open`	Open Common Data Format (CDF) file

File Read Operations

`cdflib.getCacheSize`	Number of cache buffers
`cdflib.getChecksum`	Checksum mode
`cdflib.getCompression`	Compression settings
`cdflib.getCompressionCacheSize`	Number of compression cache buffers
`cdflib.getCopyright`	Copyright notice in Common Data Format (CDF) file
`cdflib.getFormat`	Format of Common Data Format (CDF) file
`cdflib.getMajority`	Majority of variables
`cdflib.getName`	Name of Common Data Format (CDF) file
`cdflib.getReadOnlyMode`	Read-only mode
`cdflib.getStageCacheSize`	Number of cache buffers for staging
`cdflib.getVersion`	Common Data Format (CDF) library version and release information
`cdflib.inquire`	Information about Common Data Format (CDF) file

File Write Operations

`cdflib.create`	Create Common Data Format (CDF) file
`cdflib.setCacheSize`	Specify number of dotCDF cache buffers
`cdflib.setChecksum`	Specify checksum mode
`cdflib.setCompression`	Specify compression settings
`cdflib.setCompressionCacheSize`	Specify number of compression cache buffers
`cdflib.setFormat`	Specify format of Common Data Format (CDF) file
`cdflib.setMajority`	Specify majority of variables
`cdflib.setReadOnlyMode`	Specify read-only mode
`cdflib.setStageCacheSize`	Specify number of staging cache buffers for Common Data Format (CDF) file

Read Variables

`cdflib.getVarAllocRecords`	Number of records allocated for variable
`cdflib.getVarBlockingFactor`	Blocking factor for variable
`cdflib.getVarCacheSize`	Number of multifile cache buffers
`cdflib.getVarCompression`	Information about compression used by variable
`cdflib.getVarData`	Single value from record in variable
`cdflib.getVarMaxAllocRecNum`	Maximum allocated record number for variable
`cdflib.getVarMaxWrittenRecNum`	Maximum written record number for variable
`cdflib.getVarName`	Variable name, given variable number
`cdflib.getVarNum`	Variable number, given variable name
`cdflib.getVarNumRecsWritten`	Number of records written to variable
`cdflib.getVarPadValue`	Pad value for variable
`cdflib.getVarRecordData`	Entire record for variable
`cdflib.getVarReservePercent`	Compression reserve percentage for variable
`cdflib.getVarsMaxWrittenRecNum`	Maximum written record number for CDF file
`cdflib.getVarSparseRecords`	Information about how variable handles sparse records
`cdflib.hyperGetVarData`	Read hyperslab of data from variable
`cdflib.inquireVar`	Information about variable

Write Variables

`cdflib.closeVar`	Close specified variable from multifile format Common Data Format (CDF) file
`cdflib.createVar`	Create new variable
`cdflib.deleteVar`	Delete variable
`cdflib.deleteVarRecords`	Delete range of records from variable
`cdflib.hyperPutVarData`	Write hyperslab of data to variable
`cdflib.putVarData`	Write single value to variable
`cdflib.putVarRecordData`	Write entire record to variable
`cdflib.renameVar`	Change name of variable
`cdflib.setVarAllocBlockRecords`	Specify range of records to be allocated for variable
`cdflib.setVarBlockingFactor`	Specify blocking factor for variable
`cdflib.setVarCacheSize`	Specify number of multifile cache buffers for variable
`cdflib.setVarCompression`	Specify compression settings used with variable
`cdflib.setVarInitialRecs`	Specify initial number of records written to variable
`cdflib.setVarPadValue`	Specify pad value used with variable
`cdflib.setVarReservePercent`	Specify reserve percentage for variable
`cdflib.setVarsCacheSize`	Specify number of cache buffers used for all variables
`cdflib.setVarSparseRecords`	Specify how variable handles sparse records

Read Attributes

`cdflib.getAttrEntry`	Value of entry in attribute with variable scope
`cdflib.getAttrgEntry`	Value of entry in global attribute
`cdflib.getAttrMaxEntry`	Number of last entry for variable attribute
`cdflib.getAttrMaxgEntry`	Number of last entry for global attribute
`cdflib.getAttrName`	Attribute name, given attribute number
`cdflib.getAttrNum`	Attribute number, given attribute name
`cdflib.getAttrScope`	Scope of attribute
`cdflib.getNumAttrEntries`	Number of entries for attribute with variable scope
`cdflib.getNumAttrgEntries`	Number of entries for attribute with global scope
`cdflib.getNumAttributes`	Number of attributes with variable scope
`cdflib.getNumgAttributes`	Number of attributes with global scope
`cdflib.inquireAttr`	Information about attribute
`cdflib.inquireAttrEntry`	Information about entry in attribute with variable scope
`cdflib.inquireAttrgEntry`	Information about entry in attribute with global scope

Write Attributes

`cdflib.createAttr`	Create attribute
`cdflib.deleteAttr`	Delete attribute
`cdflib.deleteAttrEntry`	Delete entry from attribute with variable scope
`cdflib.deleteAttrgEntry`	Delete entry from attribute with global scope
`cdflib.putAttrEntry`	Write value to entry in attribute with variable scope
`cdflib.putAttrgEntry`	Write value to entry in attribute with global scope
`cdflib.renameAttr`	Change name of attribute

Utility Functions

`cdflib.breakdownTT2000`	Convert `CDF_TIME_TT2000` timestamp to time components (Since R2022b)
`cdflib.computeEpoch`	Convert time value to `CDF_EPOCH` value
`cdflib.computeEpoch16`	Convert time value to `CDF_EPOCH16` value
`cdflib.computeTT2000`	Convert time components to `CDF_TIME_TT2000` timestamp (Since R2022b)
`cdflib.epoch16Breakdown`	Convert `CDF_EPOCH16` value to time value
`cdflib.epochBreakdown`	Convert `CDF_EPOCH` value to time value

Topics

Import CDF Files Using High-Level Functions
Use high-level functions to import a CDF file.
Import CDF Files Using Low-Level Functions
Use low-level functions to read data from a CDF file.
Represent CDF Time Values
Extract date and time information from CDF datasets.
Export to CDF Files
Use low-level functions to write data to a CDF file.

Related Information

CDF C Library Documentation