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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 ="example.cdf");

    To use the MATLAB low-level CDF functions, you must be familiar with CDF C API programming concepts, described at

MATLAB uses CDF C library version 3.8.1.


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cdfinfoInformation about Common Data Format (CDF) file
cdfreadRead data from Common Data Format (CDF) file

Library Information

cdflib.getConstantNamesNames of Common Data Format (CDF) library constants
cdflib.getConstantValueNumeric value corresponding to Common Data Format (CDF) library constant
cdflib.getFileBackwardReturn backward compatibility mode
cdflib.getLibraryCopyrightCopyright notice of Common Data Format (CDF) library
cdflib.getLibraryVersionLibrary version and release information
cdflib.getValidateLibrary validation mode
cdflib.setFileBackwardSpecify backward compatibility mode
cdflib.setValidateSpecify library validation mode

File Operations

cdflib.closeClose Common Data Format (CDF) file
cdflib.deleteDelete Common Data Format (CDF) file
cdflib.openOpen Common Data Format (CDF) file

File Read Operations

cdflib.getCacheSizeNumber of cache buffers
cdflib.getChecksumChecksum mode
cdflib.getCompressionCompression settings
cdflib.getCompressionCacheSizeNumber of compression cache buffers
cdflib.getCopyrightCopyright notice in Common Data Format (CDF) file
cdflib.getFormatFormat of Common Data Format (CDF) file
cdflib.getMajorityMajority of variables
cdflib.getNameName of Common Data Format (CDF) file
cdflib.getReadOnlyModeRead-only mode
cdflib.getStageCacheSizeNumber of cache buffers for staging
cdflib.getVersionCommon Data Format (CDF) library version and release information
cdflib.inquireInformation about Common Data Format (CDF) file

File Write Operations

cdflib.createCreate Common Data Format (CDF) file
cdflib.setCacheSizeSpecify number of dotCDF cache buffers
cdflib.setChecksumSpecify checksum mode
cdflib.setCompressionSpecify compression settings
cdflib.setCompressionCacheSizeSpecify number of compression cache buffers
cdflib.setFormatSpecify format of Common Data Format (CDF) file
cdflib.setMajoritySpecify majority of variables
cdflib.setReadOnlyModeSpecify read-only mode
cdflib.setStageCacheSizeSpecify number of staging cache buffers for Common Data Format (CDF) file

Read Variables

cdflib.getVarAllocRecordsNumber of records allocated for variable
cdflib.getVarBlockingFactorBlocking factor for variable
cdflib.getVarCacheSizeNumber of multifile cache buffers
cdflib.getVarCompressionInformation about compression used by variable
cdflib.getVarDataSingle value from record in variable
cdflib.getVarMaxAllocRecNumMaximum allocated record number for variable
cdflib.getVarMaxWrittenRecNumMaximum written record number for variable
cdflib.getVarNameVariable name, given variable number
cdflib.getVarNumVariable number, given variable name
cdflib.getVarNumRecsWrittenNumber of records written to variable
cdflib.getVarPadValuePad value for variable
cdflib.getVarRecordDataEntire record for variable
cdflib.getVarReservePercentCompression reserve percentage for variable
cdflib.getVarsMaxWrittenRecNumMaximum written record number for CDF file
cdflib.getVarSparseRecordsInformation about how variable handles sparse records
cdflib.hyperGetVarDataRead hyperslab of data from variable
cdflib.inquireVarInformation about variable

Write Variables

cdflib.closeVarClose specified variable from multifile format Common Data Format (CDF) file
cdflib.createVarCreate new variable
cdflib.deleteVarDelete variable
cdflib.deleteVarRecordsDelete range of records from variable
cdflib.hyperPutVarDataWrite hyperslab of data to variable
cdflib.putVarDataWrite single value to variable
cdflib.putVarRecordDataWrite entire record to variable
cdflib.renameVarChange name of variable
cdflib.setVarAllocBlockRecordsSpecify range of records to be allocated for variable
cdflib.setVarBlockingFactorSpecify blocking factor for variable
cdflib.setVarCacheSizeSpecify number of multifile cache buffers for variable
cdflib.setVarCompressionSpecify compression settings used with variable
cdflib.setVarInitialRecsSpecify initial number of records written to variable
cdflib.setVarPadValueSpecify pad value used with variable
cdflib.setVarReservePercentSpecify reserve percentage for variable
cdflib.setVarsCacheSizeSpecify number of cache buffers used for all variables
cdflib.setVarSparseRecordsSpecify how variable handles sparse records

Read Attributes

cdflib.getAttrEntryValue of entry in attribute with variable scope
cdflib.getAttrgEntryValue of entry in global attribute
cdflib.getAttrMaxEntryNumber of last entry for variable attribute
cdflib.getAttrMaxgEntryNumber of last entry for global attribute
cdflib.getAttrNameAttribute name, given attribute number
cdflib.getAttrNumAttribute number, given attribute name
cdflib.getAttrScopeScope of attribute
cdflib.getNumAttrEntriesNumber of entries for attribute with variable scope
cdflib.getNumAttrgEntriesNumber of entries for attribute with global scope
cdflib.getNumAttributesNumber of attributes with variable scope
cdflib.getNumgAttributesNumber of attributes with global scope
cdflib.inquireAttrInformation about attribute
cdflib.inquireAttrEntryInformation about entry in attribute with variable scope
cdflib.inquireAttrgEntryInformation about entry in attribute with global scope

Write Attributes

cdflib.createAttrCreate attribute
cdflib.deleteAttrDelete attribute
cdflib.deleteAttrEntryDelete entry from attribute with variable scope
cdflib.deleteAttrgEntryDelete entry from attribute with global scope
cdflib.putAttrEntryWrite value to entry in attribute with variable scope
cdflib.putAttrgEntryWrite value to entry in attribute with global scope
cdflib.renameAttrChange name of attribute

Utility Functions

cdflib.breakdownTT2000Convert CDF_TIME_TT2000 timestamp to time components (Since R2022b)
cdflib.computeEpochConvert time value to CDF_EPOCH value
cdflib.computeEpoch16Convert time value to CDF_EPOCH16 value
cdflib.computeTT2000Convert time components to CDF_TIME_TT2000 timestamp (Since R2022b)
cdflib.epoch16BreakdownConvert CDF_EPOCH16 value to time value
cdflib.epochBreakdownConvert CDF_EPOCH value to time value


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