GZIP (.gz)

Background

    MIME type: application/x-gzip
    GZIP compression method and file format.
    General-purpose lossless compression method.
    Commonly used for archiving data and for exchanging files on the internet.
    Often used in combination with TAR.
    Popular on Unix systems.
    The GZIP file format is described in the internet standard recommendation RFC 1952.
    Binary format.
    Stores a single file.

Import and Export

  • Import["file.gz"] uncompresses file.gz and imports file, automatically inferring the format from the file contents.
  • Import["file.ext.gz"] uncompresses and imports a GZIP-compressed file.
  • Import["file.ext.gz",elem] imports the specified element from file.ext file.
  • Import["file.gz","format"] uncompresses a GZIP file and imports it as "format".
  • Import["file.ext.gz",{elem,suba,subb,}] imports a subelement.
  • Import["file.ext.gz",{{elem1,elem2,}}] imports multiple elements.
  • The import format can be explicitly specified with Import["file.gz",{"format",elems1,elems2,}].
  • Import["file","GZIP"] or Import["file",{"GZIP",elem,}] imports any GZIP file.
  • Export["file.ext.gz",expr] exports any expression expr to a GZIP-compressed file whose format is implied by the file name extension .ext.
  • Export["file.ext.gz",expr,elem] creates a GZIP-compressed .ext file by treating expr as specifying element elem.
  • Export["file.ext.gz",expr,opt1->val1,] exports expr with the specified option elements taken to have the specified values.
  • Export["file.ext.gz",{expr1,expr2,},{{elem1,elem2,}}] treats each expri as specifying the corresponding elemi.
  • The export format and GZIP compression method can be explicitly specified with Export["file",exprs,{"GZIP","format",elems}].
  • See the reference pages for full general information on Import and Export.
  • ImportString and ExportString can handle GZIP-compressed data.

Elements

  • The GZIP format itself does not support Import or Export elements.
  • Import elements of the GZIP-compressed file:
  • "Elements" elements and options available in this file
    "Rules"full rules for each element and option
    "Options"rules for options, properties, and settings
  • Import["file.ext.gz","Elements"] returns the names of elements available in file.ext, effectively unpacking the compressed file before importing "file.ext".

Options

  • General Export option:
  • "CompressionLevel"AutomaticGZIP compression strength, given as a number in the range 0 to 1
  • The setting "CompressionLevel"->1 corresponds to the strongest available compression, resulting in the smallest possible file size.

Examples

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Basic Examples  (2)

Export a string to a GZIP-compressed text file:

In[1]:=
Click for copyable input
Out[1]=

Convert the previous output back to a Wolfram Language string:

In[2]:=
Click for copyable input
Out[2]=

This exports graphics to a GZIP-compressed JPEG file:

In[1]:=
Click for copyable input
Out[1]=

This gives the available Import elements of the JPEG file:

In[2]:=
Click for copyable input
Out[2]=

When importing any element from a .gz file, the Wolfram Language automatically uncompresses it:

In[3]:=
Click for copyable input
Out[3]=

Export Options  (1)

See Also

"BZIP2"  "Directory"  "TAR"  "ZIP"

Introduced in 2005
(5.2)
| Updated in 2008
(7.0)