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<li><a class="reference internal" href="#"><code class="xref py py-mod docutils literal notranslate">lzma</code> — Compression using the LZMA algorithm</a><ul>
<li><a class="reference internal" href="#reading-and-writing-compressed-files">Reading and writing compressed files</a></li>
<li><a class="reference internal" href="#compressing-and-decompressing-data-in-memory">Compressing and decompressing data in memory</a></li>
<li><a class="reference internal" href="#miscellaneous">Miscellaneous</a></li>
<li><a class="reference internal" href="#specifying-custom-filter-chains">Specifying custom filter chains</a></li>
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 <section id="module-lzma">
<h1><a class="reference internal" href="#module-lzma" title="lzma: A Python wrapper for the liblzma compression library."><code class="xref py py-mod docutils literal notranslate">lzma</code></a> — Compression using the LZMA algorithm<a class="headerlink" href="#module-lzma" title="Permalink to this headline">¶</a></h1>
<div class="versionadded">
New in version 3.3.
</div>
Source code: <a class="reference external" href="https://github.com/python/cpython/tree/3.10/Lib/lzma.py">Lib/lzma.py</a>
<hr class="docutils" />
This module provides classes and convenience functions for compressing and
decompressing data using the LZMA compression algorithm. Also included is a file
interface supporting the <code class="docutils literal notranslate">.xz</code> and legacy <code class="docutils literal notranslate">.lzma</code> file formats used by the
xz utility, as well as raw compressed streams.
The interface provided by this module is very similar to that of the <a class="reference internal" href="bz2.html#module-bz2" title="bz2: Interfaces for bzip2 compression and decompression."><code class="xref py py-mod docutils literal notranslate">bz2</code></a>
module. Note that <a class="reference internal" href="#lzma.LZMAFile" title="lzma.LZMAFile"><code class="xref py py-class docutils literal notranslate">LZMAFile</code></a> and <a class="reference internal" href="bz2.html#bz2.BZ2File" title="bz2.BZ2File"><code class="xref py py-class docutils literal notranslate">bz2.BZ2File</code></a> are not
thread-safe, so if you need to use a single <a class="reference internal" href="#lzma.LZMAFile" title="lzma.LZMAFile"><code class="xref py py-class docutils literal notranslate">LZMAFile</code></a> instance
from multiple threads, it is necessary to protect it with a lock.
<dl class="py exception">
<dt class="sig sig-object py" id="lzma.LZMAError">
exception lzma.LZMAError<a class="headerlink" href="#lzma.LZMAError" title="Permalink to this definition">¶</a></dt>
<dd>This exception is raised when an error occurs during compression or
decompression, or while initializing the compressor/decompressor state.
</dd></dl>

<section id="reading-and-writing-compressed-files">
<h2>Reading and writing compressed files<a class="headerlink" href="#reading-and-writing-compressed-files" title="Permalink to this headline">¶</a></h2>
<dl class="py function">
<dt class="sig sig-object py" id="lzma.open">
lzma.open(filename, mode='rb', *, format=None, check=- 1, preset=None, filters=None, encoding=None, errors=None, newline=None)<a class="headerlink" href="#lzma.open" title="Permalink to this definition">¶</a></dt>
<dd>Open an LZMA-compressed file in binary or text mode, returning a <a class="reference internal" href="../glossary.html#term-file-object">file
object</a>.
The filename argument can be either an actual file name (given as a
<a class="reference internal" href="stdtypes.html#str" title="str"><code class="xref py py-class docutils literal notranslate">str</code></a>, <a class="reference internal" href="stdtypes.html#bytes" title="bytes"><code class="xref py py-class docutils literal notranslate">bytes</code></a> or <a class="reference internal" href="../glossary.html#term-path-like-object">path-like</a> object), in
which case the named file is opened, or it can be an existing file object
to read from or write to.
The mode argument can be any of <code class="docutils literal notranslate">&quot;r&quot;</code>, <code class="docutils literal notranslate">&quot;rb&quot;</code>, <code class="docutils literal notranslate">&quot;w&quot;</code>, <code class="docutils literal notranslate">&quot;wb&quot;</code>,
<code class="docutils literal notranslate">&quot;x&quot;</code>, <code class="docutils literal notranslate">&quot;xb&quot;</code>, <code class="docutils literal notranslate">&quot;a&quot;</code> or <code class="docutils literal notranslate">&quot;ab&quot;</code> for binary mode, or <code class="docutils literal notranslate">&quot;rt&quot;</code>,
<code class="docutils literal notranslate">&quot;wt&quot;</code>, <code class="docutils literal notranslate">&quot;xt&quot;</code>, or <code class="docutils literal notranslate">&quot;at&quot;</code> for text mode. The default is <code class="docutils literal notranslate">&quot;rb&quot;</code>.
When opening a file for reading, the format and filters arguments have
the same meanings as for <a class="reference internal" href="#lzma.LZMADecompressor" title="lzma.LZMADecompressor"><code class="xref py py-class docutils literal notranslate">LZMADecompressor</code></a>. In this case, the check
and preset arguments should not be used.
When opening a file for writing, the format, check, preset and
filters arguments have the same meanings as for <a class="reference internal" href="#lzma.LZMACompressor" title="lzma.LZMACompressor"><code class="xref py py-class docutils literal notranslate">LZMACompressor</code></a>.
For binary mode, this function is equivalent to the <a class="reference internal" href="#lzma.LZMAFile" title="lzma.LZMAFile"><code class="xref py py-class docutils literal notranslate">LZMAFile</code></a>
constructor: <code class="docutils literal notranslate">LZMAFile(filename, mode, ...)</code>. In this case, the encoding,
errors and newline arguments must not be provided.
For text mode, a <a class="reference internal" href="#lzma.LZMAFile" title="lzma.LZMAFile"><code class="xref py py-class docutils literal notranslate">LZMAFile</code></a> object is created, and wrapped in an
<a class="reference internal" href="io.html#io.TextIOWrapper" title="io.TextIOWrapper"><code class="xref py py-class docutils literal notranslate">io.TextIOWrapper</code></a> instance with the specified encoding, error
handling behavior, and line ending(s).
<div class="versionchanged">
Changed in version 3.4: Added support for the <code class="docutils literal notranslate">&quot;x&quot;</code>, <code class="docutils literal notranslate">&quot;xb&quot;</code> and <code class="docutils literal notranslate">&quot;xt&quot;</code> modes.
</div>
<div class="versionchanged">
Changed in version 3.6: Accepts a <a class="reference internal" href="../glossary.html#term-path-like-object">path-like object</a>.
</div>
</dd></dl>

<dl class="py class">
<dt class="sig sig-object py" id="lzma.LZMAFile">
class lzma.LZMAFile(filename=None, mode='r', *, format=None, check=- 1, preset=None, filters=None)<a class="headerlink" href="#lzma.LZMAFile" title="Permalink to this definition">¶</a></dt>
<dd>Open an LZMA-compressed file in binary mode.
An <a class="reference internal" href="#lzma.LZMAFile" title="lzma.LZMAFile"><code class="xref py py-class docutils literal notranslate">LZMAFile</code></a> can wrap an already-open <a class="reference internal" href="../glossary.html#term-file-object">file object</a>, or operate
directly on a named file. The filename argument specifies either the file
object to wrap, or the name of the file to open (as a <a class="reference internal" href="stdtypes.html#str" title="str"><code class="xref py py-class docutils literal notranslate">str</code></a>,
<a class="reference internal" href="stdtypes.html#bytes" title="bytes"><code class="xref py py-class docutils literal notranslate">bytes</code></a> or <a class="reference internal" href="../glossary.html#term-path-like-object">path-like</a> object). When wrapping an
existing file object, the wrapped file will not be closed when the
<a class="reference internal" href="#lzma.LZMAFile" title="lzma.LZMAFile"><code class="xref py py-class docutils literal notranslate">LZMAFile</code></a> is closed.
The mode argument can be either <code class="docutils literal notranslate">&quot;r&quot;</code> for reading (default), <code class="docutils literal notranslate">&quot;w&quot;</code> for
overwriting, <code class="docutils literal notranslate">&quot;x&quot;</code> for exclusive creation, or <code class="docutils literal notranslate">&quot;a&quot;</code> for appending. These
can equivalently be given as <code class="docutils literal notranslate">&quot;rb&quot;</code>, <code class="docutils literal notranslate">&quot;wb&quot;</code>, <code class="docutils literal notranslate">&quot;xb&quot;</code> and <code class="docutils literal notranslate">&quot;ab&quot;</code>
respectively.
If filename is a file object (rather than an actual file name), a mode of
<code class="docutils literal notranslate">&quot;w&quot;</code> does not truncate the file, and is instead equivalent to <code class="docutils literal notranslate">&quot;a&quot;</code>.
When opening a file for reading, the input file may be the concatenation of
multiple separate compressed streams. These are transparently decoded as a
single logical stream.
When opening a file for reading, the format and filters arguments have
the same meanings as for <a class="reference internal" href="#lzma.LZMADecompressor" title="lzma.LZMADecompressor"><code class="xref py py-class docutils literal notranslate">LZMADecompressor</code></a>. In this case, the check
and preset arguments should not be used.
When opening a file for writing, the format, check, preset and
filters arguments have the same meanings as for <a class="reference internal" href="#lzma.LZMACompressor" title="lzma.LZMACompressor"><code class="xref py py-class docutils literal notranslate">LZMACompressor</code></a>.
<a class="reference internal" href="#lzma.LZMAFile" title="lzma.LZMAFile"><code class="xref py py-class docutils literal notranslate">LZMAFile</code></a> supports all the members specified by
<a class="reference internal" href="io.html#io.BufferedIOBase" title="io.BufferedIOBase"><code class="xref py py-class docutils literal notranslate">io.BufferedIOBase</code></a>, except for <code class="xref py py-meth docutils literal notranslate">detach()</code> and <code class="xref py py-meth docutils literal notranslate">truncate()</code>.
Iteration and the <a class="reference internal" href="../reference/compound_stmts.html#with"><code class="xref std std-keyword docutils literal notranslate">with</code></a> statement are supported.
The following method is also provided:
<dl class="py method">
<dt class="sig sig-object py" id="lzma.LZMAFile.peek">
peek(size=- 1)<a class="headerlink" href="#lzma.LZMAFile.peek" title="Permalink to this definition">¶</a></dt>
<dd>Return buffered data without advancing the file position. At least one
byte of data will be returned, unless EOF has been reached. The exact
number of bytes returned is unspecified (the size argument is ignored).
<div class="admonition note">
Note
While calling <a class="reference internal" href="#lzma.LZMAFile.peek" title="lzma.LZMAFile.peek"><code class="xref py py-meth docutils literal notranslate">peek()</code></a> does not change the file position of
the <a class="reference internal" href="#lzma.LZMAFile" title="lzma.LZMAFile"><code class="xref py py-class docutils literal notranslate">LZMAFile</code></a>, it may change the position of the underlying
file object (e.g. if the <a class="reference internal" href="#lzma.LZMAFile" title="lzma.LZMAFile"><code class="xref py py-class docutils literal notranslate">LZMAFile</code></a> was constructed by passing a
file object for filename).
</div>
</dd></dl>

<div class="versionchanged">
Changed in version 3.4: Added support for the <code class="docutils literal notranslate">&quot;x&quot;</code> and <code class="docutils literal notranslate">&quot;xb&quot;</code> modes.
</div>
<div class="versionchanged">
Changed in version 3.5: The <a class="reference internal" href="io.html#io.BufferedIOBase.read" title="io.BufferedIOBase.read"><code class="xref py py-meth docutils literal notranslate">read()</code></a> method now accepts an argument of
<code class="docutils literal notranslate">None</code>.
</div>
<div class="versionchanged">
Changed in version 3.6: Accepts a <a class="reference internal" href="../glossary.html#term-path-like-object">path-like object</a>.
</div>
</dd></dl>

</section>
<section id="compressing-and-decompressing-data-in-memory">
<h2>Compressing and decompressing data in memory<a class="headerlink" href="#compressing-and-decompressing-data-in-memory" title="Permalink to this headline">¶</a></h2>
<dl class="py class">
<dt class="sig sig-object py" id="lzma.LZMACompressor">
class lzma.LZMACompressor(format=FORMAT_XZ, check=- 1, preset=None, filters=None)<a class="headerlink" href="#lzma.LZMACompressor" title="Permalink to this definition">¶</a></dt>
<dd>Create a compressor object, which can be used to compress data incrementally.
For a more convenient way of compressing a single chunk of data, see
<a class="reference internal" href="#lzma.compress" title="lzma.compress"><code class="xref py py-func docutils literal notranslate">compress()</code></a>.
The format argument specifies what container format should be used.
Possible values are:
<ul class="simple">
<li><dl class="simple">
<dt><code class="xref py py-const docutils literal notranslate">FORMAT_XZ</code>: The <code class="docutils literal notranslate">.xz</code> container format.</dt><dd>This is the default format.
</dd>
</dl>
</li>
<li><dl class="simple">
<dt><code class="xref py py-const docutils literal notranslate">FORMAT_ALONE</code>: The legacy <code class="docutils literal notranslate">.lzma</code> container format.</dt><dd>This format is more limited than <code class="docutils literal notranslate">.xz</code> – it does not support integrity
checks or multiple filters.
</dd>
</dl>
</li>
<li><dl class="simple">
<dt><code class="xref py py-const docutils literal notranslate">FORMAT_RAW</code>: A raw data stream, not using any container format.</dt><dd>This format specifier does not support integrity checks, and requires that
you always specify a custom filter chain (for both compression and
decompression). Additionally, data compressed in this manner cannot be
decompressed using <code class="xref py py-const docutils literal notranslate">FORMAT_AUTO</code> (see <a class="reference internal" href="#lzma.LZMADecompressor" title="lzma.LZMADecompressor"><code class="xref py py-class docutils literal notranslate">LZMADecompressor</code></a>).
</dd>
</dl>
</li>
</ul>
The check argument specifies the type of integrity check to include in the
compressed data. This check is used when decompressing, to ensure that the
data has not been corrupted. Possible values are:
<ul class="simple">
<li><code class="xref py py-const docutils literal notranslate">CHECK_NONE</code>: No integrity check.
This is the default (and the only acceptable value) for
<code class="xref py py-const docutils literal notranslate">FORMAT_ALONE</code> and <code class="xref py py-const docutils literal notranslate">FORMAT_RAW</code>.</li>
<li><code class="xref py py-const docutils literal notranslate">CHECK_CRC32</code>: 32-bit Cyclic Redundancy Check.</li>
<li><code class="xref py py-const docutils literal notranslate">CHECK_CRC64</code>: 64-bit Cyclic Redundancy Check.
This is the default for <code class="xref py py-const docutils literal notranslate">FORMAT_XZ</code>.</li>
<li><code class="xref py py-const docutils literal notranslate">CHECK_SHA256</code>: 256-bit Secure Hash Algorithm.</li>
</ul>
If the specified check is not supported, an <a class="reference internal" href="#lzma.LZMAError" title="lzma.LZMAError"><code class="xref py py-class docutils literal notranslate">LZMAError</code></a> is raised.
The compression settings can be specified either as a preset compression
level (with the preset argument), or in detail as a custom filter chain
(with the filters argument).
The preset argument (if provided) should be an integer between <code class="docutils literal notranslate">0</code> and
<code class="docutils literal notranslate">9</code> (inclusive), optionally OR-ed with the constant
<code class="xref py py-const docutils literal notranslate">PRESET_EXTREME</code>. If neither preset nor filters are given, the
default behavior is to use <code class="xref py py-const docutils literal notranslate">PRESET_DEFAULT</code> (preset level <code class="docutils literal notranslate">6</code>).
Higher presets produce smaller output, but make the compression process
slower.
<div class="admonition note">
Note
In addition to being more CPU-intensive, compression with higher presets
also requires much more memory (and produces output that needs more memory
to decompress). With preset <code class="docutils literal notranslate">9</code> for example, the overhead for an
<a class="reference internal" href="#lzma.LZMACompressor" title="lzma.LZMACompressor"><code class="xref py py-class docutils literal notranslate">LZMACompressor</code></a> object can be as high as 800 MiB. For this reason,
it is generally best to stick with the default preset.
</div>
The filters argument (if provided) should be a filter chain specifier.
See <a class="reference internal" href="#filter-chain-specs">Specifying custom filter chains</a> for details.
<dl class="py method">
<dt class="sig sig-object py" id="lzma.LZMACompressor.compress">
compress(data)<a class="headerlink" href="#lzma.LZMACompressor.compress" title="Permalink to this definition">¶</a></dt>
<dd>Compress data (a <a class="reference internal" href="stdtypes.html#bytes" title="bytes"><code class="xref py py-class docutils literal notranslate">bytes</code></a> object), returning a <a class="reference internal" href="stdtypes.html#bytes" title="bytes"><code class="xref py py-class docutils literal notranslate">bytes</code></a>
object containing compressed data for at least part of the input. Some of
data may be buffered internally, for use in later calls to
<a class="reference internal" href="#lzma.compress" title="lzma.compress"><code class="xref py py-meth docutils literal notranslate">compress()</code></a> and <a class="reference internal" href="#lzma.LZMACompressor.flush" title="lzma.LZMACompressor.flush"><code class="xref py py-meth docutils literal notranslate">flush()</code></a>. The returned data should be
concatenated with the output of any previous calls to <a class="reference internal" href="#lzma.compress" title="lzma.compress"><code class="xref py py-meth docutils literal notranslate">compress()</code></a>.
</dd></dl>

<dl class="py method">
<dt class="sig sig-object py" id="lzma.LZMACompressor.flush">
flush()<a class="headerlink" href="#lzma.LZMACompressor.flush" title="Permalink to this definition">¶</a></dt>
<dd>Finish the compression process, returning a <a class="reference internal" href="stdtypes.html#bytes" title="bytes"><code class="xref py py-class docutils literal notranslate">bytes</code></a> object
containing any data stored in the compressor’s internal buffers.
The compressor cannot be used after this method has been called.
</dd></dl>

</dd></dl>

<dl class="py class">
<dt class="sig sig-object py" id="lzma.LZMADecompressor">
class lzma.LZMADecompressor(format=FORMAT_AUTO, memlimit=None, filters=None)<a class="headerlink" href="#lzma.LZMADecompressor" title="Permalink to this definition">¶</a></dt>
<dd>Create a decompressor object, which can be used to decompress data
incrementally.
For a more convenient way of decompressing an entire compressed stream at
once, see <a class="reference internal" href="#lzma.decompress" title="lzma.decompress"><code class="xref py py-func docutils literal notranslate">decompress()</code></a>.
The format argument specifies the container format that should be used. The
default is <code class="xref py py-const docutils literal notranslate">FORMAT_AUTO</code>, which can decompress both <code class="docutils literal notranslate">.xz</code> and
<code class="docutils literal notranslate">.lzma</code> files. Other possible values are <code class="xref py py-const docutils literal notranslate">FORMAT_XZ</code>,
<code class="xref py py-const docutils literal notranslate">FORMAT_ALONE</code>, and <code class="xref py py-const docutils literal notranslate">FORMAT_RAW</code>.
The memlimit argument specifies a limit (in bytes) on the amount of memory
that the decompressor can use. When this argument is used, decompression will
fail with an <a class="reference internal" href="#lzma.LZMAError" title="lzma.LZMAError"><code class="xref py py-class docutils literal notranslate">LZMAError</code></a> if it is not possible to decompress the input
within the given memory limit.
The filters argument specifies the filter chain that was used to create
the stream being decompressed. This argument is required if format is
<code class="xref py py-const docutils literal notranslate">FORMAT_RAW</code>, but should not be used for other formats.
See <a class="reference internal" href="#filter-chain-specs">Specifying custom filter chains</a> for more information about filter chains.
<div class="admonition note">
Note
This class does not transparently handle inputs containing multiple
compressed streams, unlike <a class="reference internal" href="#lzma.decompress" title="lzma.decompress"><code class="xref py py-func docutils literal notranslate">decompress()</code></a> and <a class="reference internal" href="#lzma.LZMAFile" title="lzma.LZMAFile"><code class="xref py py-class docutils literal notranslate">LZMAFile</code></a>. To
decompress a multi-stream input with <a class="reference internal" href="#lzma.LZMADecompressor" title="lzma.LZMADecompressor"><code class="xref py py-class docutils literal notranslate">LZMADecompressor</code></a>, you must
create a new decompressor for each stream.
</div>
<dl class="py method">
<dt class="sig sig-object py" id="lzma.LZMADecompressor.decompress">
decompress(data, max_length=- 1)<a class="headerlink" href="#lzma.LZMADecompressor.decompress" title="Permalink to this definition">¶</a></dt>
<dd>Decompress data (a <a class="reference internal" href="../glossary.html#term-bytes-like-object">bytes-like object</a>), returning
uncompressed data as bytes. Some of data may be buffered
internally, for use in later calls to <a class="reference internal" href="#lzma.decompress" title="lzma.decompress"><code class="xref py py-meth docutils literal notranslate">decompress()</code></a>. The
returned data should be concatenated with the output of any
previous calls to <a class="reference internal" href="#lzma.decompress" title="lzma.decompress"><code class="xref py py-meth docutils literal notranslate">decompress()</code></a>.
If max_length is nonnegative, returns at most max_length
bytes of decompressed data. If this limit is reached and further
output can be produced, the <a class="reference internal" href="#lzma.LZMADecompressor.needs_input" title="lzma.LZMADecompressor.needs_input"><code class="xref py py-attr docutils literal notranslate">needs_input</code></a> attribute will
be set to <code class="docutils literal notranslate">False</code>. In this case, the next call to
<a class="reference internal" href="#lzma.LZMADecompressor.decompress" title="lzma.LZMADecompressor.decompress"><code class="xref py py-meth docutils literal notranslate">decompress()</code></a> may provide data as <code class="docutils literal notranslate">b''</code> to obtain
more of the output.
If all of the input data was decompressed and returned (either
because this was less than max_length bytes, or because
max_length was negative), the <a class="reference internal" href="#lzma.LZMADecompressor.needs_input" title="lzma.LZMADecompressor.needs_input"><code class="xref py py-attr docutils literal notranslate">needs_input</code></a> attribute
will be set to <code class="docutils literal notranslate">True</code>.
Attempting to decompress data after the end of stream is reached
raises an <a class="reference internal" href="exceptions.html#EOFError" title="EOFError"><code class="xref py py-exc docutils literal notranslate">EOFError</code></a>. Any data found after the end of the
stream is ignored and saved in the <a class="reference internal" href="#lzma.LZMADecompressor.unused_data" title="lzma.LZMADecompressor.unused_data"><code class="xref py py-attr docutils literal notranslate">unused_data</code></a> attribute.
<div class="versionchanged">
Changed in version 3.5: Added the max_length parameter.
</div>
</dd></dl>

<dl class="py attribute">
<dt class="sig sig-object py" id="lzma.LZMADecompressor.check">
check<a class="headerlink" href="#lzma.LZMADecompressor.check" title="Permalink to this definition">¶</a></dt>
<dd>The ID of the integrity check used by the input stream. This may be
<code class="xref py py-const docutils literal notranslate">CHECK_UNKNOWN</code> until enough of the input has been decoded to
determine what integrity check it uses.
</dd></dl>

<dl class="py attribute">
<dt class="sig sig-object py" id="lzma.LZMADecompressor.eof">
eof<a class="headerlink" href="#lzma.LZMADecompressor.eof" title="Permalink to this definition">¶</a></dt>
<dd><code class="docutils literal notranslate">True</code> if the end-of-stream marker has been reached.
</dd></dl>

<dl class="py attribute">
<dt class="sig sig-object py" id="lzma.LZMADecompressor.unused_data">
unused_data<a class="headerlink" href="#lzma.LZMADecompressor.unused_data" title="Permalink to this definition">¶</a></dt>
<dd>Data found after the end of the compressed stream.
Before the end of the stream is reached, this will be <code class="docutils literal notranslate">b&quot;&quot;</code>.
</dd></dl>

<dl class="py attribute">
<dt class="sig sig-object py" id="lzma.LZMADecompressor.needs_input">
needs_input<a class="headerlink" href="#lzma.LZMADecompressor.needs_input" title="Permalink to this definition">¶</a></dt>
<dd><code class="docutils literal notranslate">False</code> if the <a class="reference internal" href="#lzma.LZMADecompressor.decompress" title="lzma.LZMADecompressor.decompress"><code class="xref py py-meth docutils literal notranslate">decompress()</code></a> method can provide more
decompressed data before requiring new uncompressed input.
<div class="versionadded">
New in version 3.5.
</div>
</dd></dl>

</dd></dl>

<dl class="py function">
<dt class="sig sig-object py" id="lzma.compress">
lzma.compress(data, format=FORMAT_XZ, check=- 1, preset=None, filters=None)<a class="headerlink" href="#lzma.compress" title="Permalink to this definition">¶</a></dt>
<dd>Compress data (a <a class="reference internal" href="stdtypes.html#bytes" title="bytes"><code class="xref py py-class docutils literal notranslate">bytes</code></a> object), returning the compressed data as a
<a class="reference internal" href="stdtypes.html#bytes" title="bytes"><code class="xref py py-class docutils literal notranslate">bytes</code></a> object.
See <a class="reference internal" href="#lzma.LZMACompressor" title="lzma.LZMACompressor"><code class="xref py py-class docutils literal notranslate">LZMACompressor</code></a> above for a description of the format, check,
preset and filters arguments.
</dd></dl>

<dl class="py function">
<dt class="sig sig-object py" id="lzma.decompress">
lzma.decompress(data, format=FORMAT_AUTO, memlimit=None, filters=None)<a class="headerlink" href="#lzma.decompress" title="Permalink to this definition">¶</a></dt>
<dd>Decompress data (a <a class="reference internal" href="stdtypes.html#bytes" title="bytes"><code class="xref py py-class docutils literal notranslate">bytes</code></a> object), returning the uncompressed data
as a <a class="reference internal" href="stdtypes.html#bytes" title="bytes"><code class="xref py py-class docutils literal notranslate">bytes</code></a> object.
If data is the concatenation of multiple distinct compressed streams,
decompress all of these streams, and return the concatenation of the results.
See <a class="reference internal" href="#lzma.LZMADecompressor" title="lzma.LZMADecompressor"><code class="xref py py-class docutils literal notranslate">LZMADecompressor</code></a> above for a description of the format,
memlimit and filters arguments.
</dd></dl>

</section>
<section id="miscellaneous">
<h2>Miscellaneous<a class="headerlink" href="#miscellaneous" title="Permalink to this headline">¶</a></h2>
<dl class="py function">
<dt class="sig sig-object py" id="lzma.is_check_supported">
lzma.is_check_supported(check)<a class="headerlink" href="#lzma.is_check_supported" title="Permalink to this definition">¶</a></dt>
<dd>Return <code class="docutils literal notranslate">True</code> if the given integrity check is supported on this system.
<code class="xref py py-const docutils literal notranslate">CHECK_NONE</code> and <code class="xref py py-const docutils literal notranslate">CHECK_CRC32</code> are always supported.
<code class="xref py py-const docutils literal notranslate">CHECK_CRC64</code> and <code class="xref py py-const docutils literal notranslate">CHECK_SHA256</code> may be unavailable if you are
using a version of liblzma that was compiled with a limited
feature set.
</dd></dl>

</section>
<section id="specifying-custom-filter-chains">
<h2>Specifying custom filter chains<a class="headerlink" href="#specifying-custom-filter-chains" title="Permalink to this headline">¶</a></h2>
A filter chain specifier is a sequence of dictionaries, where each dictionary
contains the ID and options for a single filter. Each dictionary must contain
the key <code class="docutils literal notranslate">&quot;id&quot;</code>, and may contain additional keys to specify filter-dependent
options. Valid filter IDs are as follows:
<ul class="simple">
<li><dl class="simple">
<dt>Compression filters:</dt><dd><ul>
<li><code class="xref py py-const docutils literal notranslate">FILTER_LZMA1</code> (for use with <code class="xref py py-const docutils literal notranslate">FORMAT_ALONE</code>)</li>
<li><code class="xref py py-const docutils literal notranslate">FILTER_LZMA2</code> (for use with <code class="xref py py-const docutils literal notranslate">FORMAT_XZ</code> and <code class="xref py py-const docutils literal notranslate">FORMAT_RAW</code>)</li>
</ul>
</dd>
</dl>
</li>
<li><dl class="simple">
<dt>Delta filter:</dt><dd><ul>
<li><code class="xref py py-const docutils literal notranslate">FILTER_DELTA</code></li>
</ul>
</dd>
</dl>
</li>
<li><dl class="simple">
<dt>Branch-Call-Jump (BCJ) filters:</dt><dd><ul>
<li><code class="xref py py-const docutils literal notranslate">FILTER_X86</code></li>
<li><code class="xref py py-const docutils literal notranslate">FILTER_IA64</code></li>
<li><code class="xref py py-const docutils literal notranslate">FILTER_ARM</code></li>
<li><code class="xref py py-const docutils literal notranslate">FILTER_ARMTHUMB</code></li>
<li><code class="xref py py-const docutils literal notranslate">FILTER_POWERPC</code></li>
<li><code class="xref py py-const docutils literal notranslate">FILTER_SPARC</code></li>
</ul>
</dd>
</dl>
</li>
</ul>
A filter chain can consist of up to 4 filters, and cannot be empty. The last
filter in the chain must be a compression filter, and any other filters must be
delta or BCJ filters.
Compression filters support the following options (specified as additional
entries in the dictionary representing the filter):
<blockquote>
<div><ul class="simple">
<li><code class="docutils literal notranslate">preset</code>: A compression preset to use as a source of default values for
options that are not specified explicitly.</li>
<li><code class="docutils literal notranslate">dict_size</code>: Dictionary size in bytes. This should be between 4 KiB and
1.5 GiB (inclusive).</li>
<li><code class="docutils literal notranslate">lc</code>: Number of literal context bits.</li>
<li><code class="docutils literal notranslate">lp</code>: Number of literal position bits. The sum <code class="docutils literal notranslate">lc + lp</code> must be at
most 4.</li>
<li><code class="docutils literal notranslate">pb</code>: Number of position bits; must be at most 4.</li>
<li><code class="docutils literal notranslate">mode</code>: <code class="xref py py-const docutils literal notranslate">MODE_FAST</code> or <code class="xref py py-const docutils literal notranslate">MODE_NORMAL</code>.</li>
<li><code class="docutils literal notranslate">nice_len</code>: What should be considered a “nice length” for a match.
This should be 273 or less.</li>
<li><code class="docutils literal notranslate">mf</code>: What match finder to use – <code class="xref py py-const docutils literal notranslate">MF_HC3</code>, <code class="xref py py-const docutils literal notranslate">MF_HC4</code>,
<code class="xref py py-const docutils literal notranslate">MF_BT2</code>, <code class="xref py py-const docutils literal notranslate">MF_BT3</code>, or <code class="xref py py-const docutils literal notranslate">MF_BT4</code>.</li>
<li><code class="docutils literal notranslate">depth</code>: Maximum search depth used by match finder. 0 (default) means to
select automatically based on other filter options.</li>
</ul>
</div></blockquote>
The delta filter stores the differences between bytes, producing more repetitive
input for the compressor in certain circumstances. It supports one option,
<code class="docutils literal notranslate">dist</code>. This indicates the distance between bytes to be subtracted. The
default is 1, i.e. take the differences between adjacent bytes.
The BCJ filters are intended to be applied to machine code. They convert
relative branches, calls and jumps in the code to use absolute addressing, with
the aim of increasing the redundancy that can be exploited by the compressor.
These filters support one option, <code class="docutils literal notranslate">start_offset</code>. This specifies the address
that should be mapped to the beginning of the input data. The default is 0.
</section>
<section id="examples">
<h2>Examples<a class="headerlink" href="#examples" title="Permalink to this headline">¶</a></h2>
Reading in a compressed file:
<div class="highlight-python3 notranslate"><div class="highlight"><pre>import lzma
with lzma.open(&quot;file.xz&quot;) as f:
 file_content = f.read()
</pre></div>
</div>
Creating a compressed file:
<div class="highlight-python3 notranslate"><div class="highlight"><pre>import lzma
data = b&quot;Insert Data Here&quot;
with lzma.open(&quot;file.xz&quot;, &quot;w&quot;) as f:
 f.write(data)
</pre></div>
</div>
Compressing data in memory:
<div class="highlight-python3 notranslate"><div class="highlight"><pre>import lzma
data_in = b&quot;Insert Data Here&quot;
data_out = lzma.compress(data_in)
</pre></div>
</div>
Incremental compression:
<div class="highlight-python3 notranslate"><div class="highlight"><pre>import lzma
lzc = lzma.LZMACompressor()
out1 = lzc.compress(b&quot;Some data\n&quot;)
out2 = lzc.compress(b&quot;Another piece of data\n&quot;)
out3 = lzc.compress(b&quot;Even more data\n&quot;)
out4 = lzc.flush()
# Concatenate all the partial results:
result = b&quot;&quot;.join([out1, out2, out3, out4])
</pre></div>
</div>
Writing compressed data to an already-open file:
<div class="highlight-python3 notranslate"><div class="highlight"><pre>import lzma
with open(&quot;file.xz&quot;, &quot;wb&quot;) as f:
 f.write(b&quot;This data will not be compressed\n&quot;)
 with lzma.open(f, &quot;w&quot;) as lzf:
 lzf.write(b&quot;This *will* be compressed\n&quot;)
 f.write(b&quot;Not compressed\n&quot;)
</pre></div>
</div>
Creating a compressed file using a custom filter chain:
<div class="highlight-python3 notranslate"><div class="highlight"><pre>import lzma
my_filters = [
 {&quot;id&quot;: lzma.FILTER_DELTA, &quot;dist&quot;: 5},
 {&quot;id&quot;: lzma.FILTER_LZMA2, &quot;preset&quot;: 7 | lzma.PRESET_EXTREME},
]
with lzma.open(&quot;file.xz&quot;, &quot;w&quot;, filters=my_filters) as f:
 f.write(b&quot;blah blah blah&quot;)
</pre></div>
</div>
</section>
</section>

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 <ul>
<li><a class="reference internal" href="#"><code class="xref py py-mod docutils literal notranslate">lzma</code> — Compression using the LZMA algorithm</a><ul>
<li><a class="reference internal" href="#reading-and-writing-compressed-files">Reading and writing compressed files</a></li>
<li><a class="reference internal" href="#compressing-and-decompressing-data-in-memory">Compressing and decompressing data in memory</a></li>
<li><a class="reference internal" href="#miscellaneous">Miscellaneous</a></li>
<li><a class="reference internal" href="#specifying-custom-filter-chains">Specifying custom filter chains</a></li>
<li><a class="reference internal" href="#examples">Examples</a></li>
</ul>
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