NASACDF (.cdf)

Background & Context

    • MIME type: application/x-cdf
    • CDF data file format.
    • General-purpose, self-describing format for storing multidimensional datasets.
    • Used for storage, management, and exchange of scientific data and images.
    • CDF is an acronym for Common Data Format.
    • Developed since 1985 by the National Space Science Data Center at NASA.
    • Binary file format.
    • Related to, but incompatible with, netCDF.

Import & Export

  • Import["file.cdf"] imports a CDF file, returning the names of the datasets stored in the file.
  • Export["file.cdf",expr] exports an array or a Graphics object to a CDF file.
  • Import["file.cdf"] returns a list of strings representing the names of all datasets contained in the file.
  • Export["file.cdf",{expr1,…},{"Datasets",{"/dataset1",…}}] creates a CDF file, storing the arrays or Graphics objects {expr1,…} as separate datasets.
  • Import["file.cdf",elem] imports the specified element from a CDF file.
  • Import["file.cdf",{elem,suba,subb,…}] imports a subelement.
  • Import["file.cdf",{{elem1,elem2,…}}] imports multiple elements.
  • The import format can be specified with Import["file","NASACDF"] or Import["file",{"NASACDF",elem,…}].
  • Export["file.cdf",expr, elem] creates a NASA CDF file by treating expr as specifying element elem.
  • Export["file.cdf",{expr1,expr2,…},{{elem1,elem2,…}}] treats each expri as specifying the corresponding elemi.
  • Export["file.cdf",expr,opt1->val1,…] exports expr with the specified option elements taken to have the specified values.
  • Export["file.cdf",{elem1->expr1,elem2->expr2,…},"Rules"] uses rules to specify the elements to be exported.
  • See the following reference pages for full general information:
  • Import, Exportimport from or export to a file
    CloudImport, CloudExportimport from or export to a cloud object
    ImportString, ExportStringimport from or export to a string
    ImportByteArray, ExportByteArrayimport from or export to a byte array

Import Elements

  • General Import elements:
  • "Elements" list of elements and options available in this file
    "Summary"summary of the file
    "Rules"list of rules for all available elements
  • Data representation elements:
  • "Data"all datasets imported as a list of arrays
    "Datasets"names of all datasets
  • Import by default uses the "Datasets" element for the CDF format.
  • Specifying and selecting datasets:
  • "Datasets",nnth dataset
    "Datasets",datasetnamed dataset
  • The following values can be given for "DataFormat":
  • "Date"dates, given as DateList specifications
    "Integer8"8-bit integers
    "Integer16"16-bit integers
    "Integer32"32-bit integers
    "UnsignedInteger8"unsigned 8-bit integers
    "UnsignedInteger16"unsigned 16-bit integers
    "UnsignedInteger32"unsigned 32-bit integers
    "Real32"IEEE single‐precision numbers
    "Real64"IEEE double‐precision numbers
    "String"strings of ASCII characters
  • Meta-information elements:
  • "Annotations"meta-information for each dataset
    "DataEncoding"specifies how each dataset is compressed
    "DataFormat"type used to represent each dataset
    "Dimensions"data dimensions of each dataset
    "Metadata"general meta-information as a list of rules
  • "DataEncoding" can take the following values:
  • Noneno data compression is used
    "AdaptiveHuffman"adaptive Huffman encoding
    "GZIP"GZIP compression
    "Huffman"Huffman encoding
    "RLE"run-length encoding

Options

  • Export options:
  • "Append"Falsewhether to append to an existing file
    "LargeFileSupport"Falsewhether to export a 64-bit NASA CDF file
  • With the default setting "LargeFileSupport"->False, the exported file uses a 32-bit data representation conforming to Version 2.7 of the CDF format.
  • 64-bit enhanced CDF 3.1 files can be created with "LargeFileSupport"->True.

Examples

Basic Examples  (7)

Get the dataset names:

Show the import elements available in the example file:

Read all meta-information:

Import the "LATITUDE" and "LONGITUD" datasets:

Importing the "EPOCH" dataset returns a date in the form given by DateList:

Read a data array from the example file and render it using MatrixPlot:

Rasterize the earlier graphics and export them as an array of color values to NASA CDF:

Export a list of integers to NASA CDF, explicitly specifying the dataset name:

This imports the generated NASA CDF file: