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170 </li>171 <li id="cpython-language-and-version">172 <a href="../index.html">3.15.0a6 Documentation</a> »173 </li>174 175 <li class="nav-item nav-item-1"><a href="index.html" >The Python Standard Library</a> »</li>176 <li class="nav-item nav-item-2"><a href="archiving.html" accesskey="U">Data Compression and Archiving</a> »</li>177 <li class="nav-item nav-item-this"><a href=""><code class="xref py py-mod docutils literal notranslate"><span class="pre">zlib</span></code> — Compression compatible with <strong class="program">gzip</strong></a></li>178 <li class="right">179 180 181 <div class="inline-search" role="search">182 <form class="inline-search" action="../search.html" method="get">183 <input placeholder="Quick search" aria-label="Quick search" type="search" name="q" id="search-box">184 <input type="submit" value="Go">185 </form>186 </div>187 |188 </li>189 <li class="right">190<label class="theme-selector-label">191 Theme192 <select class="theme-selector" 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href="../glossary.html#term-optional-module"><span class="xref std std-term">optional module</span></a>.213If it is missing from your copy of CPython,214look for documentation from your distributor (that is,215whoever provided Python to you).216If you are the distributor, see <a class="reference internal" href="../using/configure.html#optional-module-requirements"><span class="std std-ref">Requirements for optional modules</span></a>.</p>217<p>zlib’s functions have many options and often need to be used in a particular218order. This documentation doesn’t attempt to cover all of the permutations;219consult the <a class="reference external" href="https://www.zlib.net/manual.html">zlib manual</a> for authoritative220information.</p>221<p>For reading and writing <code class="docutils literal notranslate"><span class="pre">.gz</span></code> files see the <a class="reference internal" href="gzip.html#module-gzip" title="gzip: Interfaces for gzip compression and decompression using file objects."><code class="xref py py-mod docutils literal notranslate"><span class="pre">gzip</span></code></a> module.</p>222<p>The available exception and functions in this module are:</p>223<dl class="py exception">224<dt class="sig sig-object py" id="zlib.error">225<em class="property"><span class="k"><span class="pre">exception</span></span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">zlib.</span></span><span class="sig-name descname"><span class="pre">error</span></span><a class="headerlink" href="#zlib.error" title="Link to this definition">¶</a></dt>226<dd><p>Exception raised on compression and decompression errors.</p>227</dd></dl>228 229<dl class="py function">230<dt class="sig sig-object py" id="zlib.adler32">231<span class="sig-prename descclassname"><span class="pre">zlib.</span></span><span class="sig-name descname"><span class="pre">adler32</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">data</span></span></em><span class="optional">[</span>, <em class="sig-param"><span class="n"><span class="pre">value</span></span></em><span class="optional">]</span><span class="sig-paren">)</span><a class="headerlink" href="#zlib.adler32" title="Link to this definition">¶</a></dt>232<dd><p>Computes an Adler-32 checksum of <em>data</em>. (An Adler-32 checksum is almost as233reliable as a CRC32 but can be computed much more quickly.) The result234is an unsigned 32-bit integer. If <em>value</em> is present, it is used as235the starting value of the checksum; otherwise, a default value of 1236is used. Passing in <em>value</em> allows computing a running checksum over the237concatenation of several inputs. The algorithm is not cryptographically238strong, and should not be used for authentication or digital signatures. Since239the algorithm is designed for use as a checksum algorithm, it is not suitable240for use as a general hash algorithm.</p>241<div class="versionchanged">242<p><span class="versionmodified changed">Changed in version 3.0: </span>The result is always unsigned.</p>243</div>244</dd></dl>245 246<dl class="py function">247<dt class="sig sig-object py" id="zlib.adler32_combine">248<span class="sig-prename descclassname"><span class="pre">zlib.</span></span><span class="sig-name descname"><span class="pre">adler32_combine</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">adler1</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">adler2</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">len2</span></span></em>, <em class="sig-param"><span class="positional-only-separator o"><abbr title="Positional-only parameter separator (PEP 570)"><span class="pre">/</span></abbr></span></em><span class="sig-paren">)</span><a class="headerlink" href="#zlib.adler32_combine" title="Link to this definition">¶</a></dt>249<dd><p>Combine two Adler-32 checksums into one.</p>250<p>Given the Adler-32 checksum <em>adler1</em> of a sequence <code class="docutils literal notranslate"><span class="pre">A</span></code> and the251Adler-32 checksum <em>adler2</em> of a sequence <code class="docutils literal notranslate"><span class="pre">B</span></code> of length <em>len2</em>,252return the Adler-32 checksum of <code class="docutils literal notranslate"><span class="pre">A</span></code> and <code class="docutils literal notranslate"><span class="pre">B</span></code> concatenated.</p>253<p>This function is typically useful to combine Adler-32 checksums254that were concurrently computed. To compute checksums sequentially, use255<a class="reference internal" href="#zlib.adler32" title="zlib.adler32"><code class="xref py py-func docutils literal notranslate"><span class="pre">adler32()</span></code></a> with the running checksum as the <code class="docutils literal notranslate"><span class="pre">value</span></code> argument.</p>256<div class="versionadded">257<p><span class="versionmodified added">Added in version 3.15.</span></p>258</div>259</dd></dl>260 261<dl class="py function">262<dt class="sig sig-object py" id="zlib.compress">263<span class="sig-prename descclassname"><span class="pre">zlib.</span></span><span class="sig-name descname"><span class="pre">compress</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">data</span></span></em>, <em class="sig-param"><span class="positional-only-separator o"><abbr title="Positional-only parameter separator (PEP 570)"><span class="pre">/</span></abbr></span></em>, <em class="sig-param"><span class="n"><span class="pre">level</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">Z_DEFAULT_COMPRESSION</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">wbits</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">MAX_WBITS</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#zlib.compress" title="Link to this definition">¶</a></dt>264<dd><p>Compresses the bytes in <em>data</em>, returning a bytes object containing compressed data.265<em>level</em> is an integer from <code class="docutils literal notranslate"><span class="pre">0</span></code> to <code class="docutils literal notranslate"><span class="pre">9</span></code> or <code class="docutils literal notranslate"><span class="pre">-1</span></code> controlling the level of compression;266See <a class="reference internal" href="#zlib.Z_BEST_SPEED" title="zlib.Z_BEST_SPEED"><code class="xref py py-const docutils literal notranslate"><span class="pre">Z_BEST_SPEED</span></code></a> (<code class="docutils literal notranslate"><span class="pre">1</span></code>), <a class="reference internal" href="#zlib.Z_BEST_COMPRESSION" title="zlib.Z_BEST_COMPRESSION"><code class="xref py py-const docutils literal notranslate"><span class="pre">Z_BEST_COMPRESSION</span></code></a> (<code class="docutils literal notranslate"><span class="pre">9</span></code>),267<a class="reference internal" href="#zlib.Z_NO_COMPRESSION" title="zlib.Z_NO_COMPRESSION"><code class="xref py py-const docutils literal notranslate"><span class="pre">Z_NO_COMPRESSION</span></code></a> (<code class="docutils literal notranslate"><span class="pre">0</span></code>), and the default,268<a class="reference internal" href="#zlib.Z_DEFAULT_COMPRESSION" title="zlib.Z_DEFAULT_COMPRESSION"><code class="xref py py-const docutils literal notranslate"><span class="pre">Z_DEFAULT_COMPRESSION</span></code></a> (<code class="docutils literal notranslate"><span class="pre">-1</span></code>) for more information about these values.</p>269<p id="compress-wbits">The <em>wbits</em> argument controls the size of the history buffer (or the270“window size”) used when compressing data, and whether a header and271trailer is included in the output. It can take several ranges of values,272defaulting to <code class="docutils literal notranslate"><span class="pre">15</span></code> (<a class="reference internal" href="#zlib.MAX_WBITS" title="zlib.MAX_WBITS"><code class="xref py py-const docutils literal notranslate"><span class="pre">MAX_WBITS</span></code></a>):</p>273<ul class="simple">274<li><p>+9 to +15: The base-two logarithm of the window size, which275therefore ranges between 512 and 32768. Larger values produce276better compression at the expense of greater memory usage. The277resulting output will include a zlib-specific header and trailer.</p></li>278<li><p>−9 to −15: Uses the absolute value of <em>wbits</em> as the279window size logarithm, while producing a raw output stream with no280header or trailing checksum.</p></li>281<li><p>+25 to +31 = 16 + (9 to 15): Uses the low 4 bits of the value as the282window size logarithm, while including a basic <strong class="program">gzip</strong> header283and trailing checksum in the output.</p></li>284</ul>285<p>Raises the <a class="reference internal" href="#zlib.error" title="zlib.error"><code class="xref py py-exc docutils literal notranslate"><span class="pre">error</span></code></a> exception if any error occurs.</p>286<div class="versionchanged">287<p><span class="versionmodified changed">Changed in version 3.6: </span><em>level</em> can now be used as a keyword parameter.</p>288</div>289<div class="versionchanged">290<p><span class="versionmodified changed">Changed in version 3.11: </span>The <em>wbits</em> parameter is now available to set window bits and291compression type.</p>292</div>293</dd></dl>294 295<dl class="py function">296<dt class="sig sig-object py" id="zlib.compressobj">297<span class="sig-prename descclassname"><span class="pre">zlib.</span></span><span class="sig-name descname"><span class="pre">compressobj</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">level=Z_DEFAULT_COMPRESSION</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">method=DEFLATED</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">wbits=MAX_WBITS</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">memLevel=DEF_MEM_LEVEL</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">strategy=Z_DEFAULT_STRATEGY</span></span></em><span class="optional">[</span>, <em class="sig-param"><span class="n"><span class="pre">zdict</span></span></em><span class="optional">]</span><span class="sig-paren">)</span><a class="headerlink" href="#zlib.compressobj" title="Link to this definition">¶</a></dt>298<dd><p>Returns a compression object, to be used for compressing data streams that won’t299fit into memory at once.</p>300<p><em>level</em> is the compression level – an integer from <code class="docutils literal notranslate"><span class="pre">0</span></code> to <code class="docutils literal notranslate"><span class="pre">9</span></code> or <code class="docutils literal notranslate"><span class="pre">-1</span></code>.301See <a class="reference internal" href="#zlib.Z_BEST_SPEED" title="zlib.Z_BEST_SPEED"><code class="xref py py-const docutils literal notranslate"><span class="pre">Z_BEST_SPEED</span></code></a> (<code class="docutils literal notranslate"><span class="pre">1</span></code>), <a class="reference internal" href="#zlib.Z_BEST_COMPRESSION" title="zlib.Z_BEST_COMPRESSION"><code class="xref py py-const docutils literal notranslate"><span class="pre">Z_BEST_COMPRESSION</span></code></a> (<code class="docutils literal notranslate"><span class="pre">9</span></code>),302<a class="reference internal" href="#zlib.Z_NO_COMPRESSION" title="zlib.Z_NO_COMPRESSION"><code class="xref py py-const docutils literal notranslate"><span class="pre">Z_NO_COMPRESSION</span></code></a> (<code class="docutils literal notranslate"><span class="pre">0</span></code>), and the default,303<a class="reference internal" href="#zlib.Z_DEFAULT_COMPRESSION" title="zlib.Z_DEFAULT_COMPRESSION"><code class="xref py py-const docutils literal notranslate"><span class="pre">Z_DEFAULT_COMPRESSION</span></code></a> (<code class="docutils literal notranslate"><span class="pre">-1</span></code>) for more information about these values.</p>304<p><em>method</em> is the compression algorithm. Currently, the only supported value is305<a class="reference internal" href="#zlib.DEFLATED" title="zlib.DEFLATED"><code class="xref py py-const docutils literal notranslate"><span class="pre">DEFLATED</span></code></a>.</p>306<p>The <em>wbits</em> parameter controls the size of the history buffer (or the307“window size”), and what header and trailer format will be used. It has308the same meaning as <a class="reference external" href="#compress-wbits">described for compress()</a>.</p>309<p>The <em>memLevel</em> argument controls the amount of memory used for the310internal compression state. Valid values range from <code class="docutils literal notranslate"><span class="pre">1</span></code> to <code class="docutils literal notranslate"><span class="pre">9</span></code>.311Higher values use more memory, but are faster and produce smaller output.</p>312<p><em>strategy</em> is used to tune the compression algorithm. Possible values are313<a class="reference internal" href="#zlib.Z_DEFAULT_STRATEGY" title="zlib.Z_DEFAULT_STRATEGY"><code class="xref py py-const docutils literal notranslate"><span class="pre">Z_DEFAULT_STRATEGY</span></code></a>, <a class="reference internal" href="#zlib.Z_FILTERED" title="zlib.Z_FILTERED"><code class="xref py py-const docutils literal notranslate"><span class="pre">Z_FILTERED</span></code></a>, <a class="reference internal" href="#zlib.Z_HUFFMAN_ONLY" title="zlib.Z_HUFFMAN_ONLY"><code class="xref py py-const docutils literal notranslate"><span class="pre">Z_HUFFMAN_ONLY</span></code></a>,314<a class="reference internal" href="#zlib.Z_RLE" title="zlib.Z_RLE"><code class="xref py py-const docutils literal notranslate"><span class="pre">Z_RLE</span></code></a> and <a class="reference internal" href="#zlib.Z_FIXED" title="zlib.Z_FIXED"><code class="xref py py-const docutils literal notranslate"><span class="pre">Z_FIXED</span></code></a>.</p>315<p><em>zdict</em> is a predefined compression dictionary. This is a sequence of bytes316(such as a <a class="reference internal" href="stdtypes.html#bytes" title="bytes"><code class="xref py py-class docutils literal notranslate"><span class="pre">bytes</span></code></a> object) containing subsequences that are expected317to occur frequently in the data that is to be compressed. Those subsequences318that are expected to be most common should come at the end of the dictionary.</p>319<div class="versionchanged">320<p><span class="versionmodified changed">Changed in version 3.3: </span>Added the <em>zdict</em> parameter and keyword argument support.</p>321</div>322</dd></dl>323 324<dl class="py function">325<dt class="sig sig-object py" id="zlib.crc32">326<span class="sig-prename descclassname"><span class="pre">zlib.</span></span><span class="sig-name descname"><span class="pre">crc32</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">data</span></span></em><span class="optional">[</span>, <em class="sig-param"><span class="n"><span class="pre">value</span></span></em><span class="optional">]</span><span class="sig-paren">)</span><a class="headerlink" href="#zlib.crc32" title="Link to this definition">¶</a></dt>327<dd><p id="index-0">Computes a CRC (Cyclic Redundancy Check) checksum of <em>data</em>. The328result is an unsigned 32-bit integer. If <em>value</em> is present, it is used329as the starting value of the checksum; otherwise, a default value of 0330is used. Passing in <em>value</em> allows computing a running checksum over the331concatenation of several inputs. The algorithm is not cryptographically332strong, and should not be used for authentication or digital signatures. Since333the algorithm is designed for use as a checksum algorithm, it is not suitable334for use as a general hash algorithm.</p>335<div class="versionchanged">336<p><span class="versionmodified changed">Changed in version 3.0: </span>The result is always unsigned.</p>337</div>338</dd></dl>339 340<dl class="py function">341<dt class="sig sig-object py" id="zlib.crc32_combine">342<span class="sig-prename descclassname"><span class="pre">zlib.</span></span><span class="sig-name descname"><span class="pre">crc32_combine</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">crc1</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">crc2</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">len2</span></span></em>, <em class="sig-param"><span class="positional-only-separator o"><abbr title="Positional-only parameter separator (PEP 570)"><span class="pre">/</span></abbr></span></em><span class="sig-paren">)</span><a class="headerlink" href="#zlib.crc32_combine" title="Link to this definition">¶</a></dt>343<dd><p>Combine two CRC-32 checksums into one.</p>344<p>Given the CRC-32 checksum <em>crc1</em> of a sequence <code class="docutils literal notranslate"><span class="pre">A</span></code> and the345CRC-32 checksum <em>crc2</em> of a sequence <code class="docutils literal notranslate"><span class="pre">B</span></code> of length <em>len2</em>,346return the CRC-32 checksum of <code class="docutils literal notranslate"><span class="pre">A</span></code> and <code class="docutils literal notranslate"><span class="pre">B</span></code> concatenated.</p>347<p>This function is typically useful to combine CRC-32 checksums348that were concurrently computed. To compute checksums sequentially, use349<a class="reference internal" href="#zlib.crc32" title="zlib.crc32"><code class="xref py py-func docutils literal notranslate"><span class="pre">crc32()</span></code></a> with the running checksum as the <code class="docutils literal notranslate"><span class="pre">value</span></code> argument.</p>350<div class="versionadded">351<p><span class="versionmodified added">Added in version 3.15.</span></p>352</div>353</dd></dl>354 355<dl class="py function">356<dt class="sig sig-object py" id="zlib.decompress">357<span class="sig-prename descclassname"><span class="pre">zlib.</span></span><span class="sig-name descname"><span class="pre">decompress</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">data</span></span></em>, <em class="sig-param"><span class="positional-only-separator o"><abbr title="Positional-only parameter separator (PEP 570)"><span class="pre">/</span></abbr></span></em>, <em class="sig-param"><span class="n"><span class="pre">wbits</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">MAX_WBITS</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">bufsize</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">DEF_BUF_SIZE</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#zlib.decompress" title="Link to this definition">¶</a></dt>358<dd><p>Decompresses the bytes in <em>data</em>, returning a bytes object containing the359uncompressed data. The <em>wbits</em> parameter depends on360the format of <em>data</em>, and is discussed further below.361If <em>bufsize</em> is given, it is used as the initial size of the output362buffer. Raises the <a class="reference internal" href="#zlib.error" title="zlib.error"><code class="xref py py-exc docutils literal notranslate"><span class="pre">error</span></code></a> exception if any error occurs.</p>363<p id="decompress-wbits">The <em>wbits</em> parameter controls the size of the history buffer364(or “window size”), and what header and trailer format is expected.365It is similar to the parameter for <a class="reference internal" href="#zlib.compressobj" title="zlib.compressobj"><code class="xref py py-func docutils literal notranslate"><span class="pre">compressobj()</span></code></a>, but accepts366more ranges of values:</p>367<ul class="simple">368<li><p>+8 to +15: The base-two logarithm of the window size. The input369must include a zlib header and trailer.</p></li>370<li><p>0: Automatically determine the window size from the zlib header.371Only supported since zlib 1.2.3.5.</p></li>372<li><p>−8 to −15: Uses the absolute value of <em>wbits</em> as the window size373logarithm. The input must be a raw stream with no header or trailer.</p></li>374<li><p>+24 to +31 = 16 + (8 to 15): Uses the low 4 bits of the value as375the window size logarithm. The input must include a gzip header and376trailer.</p></li>377<li><p>+40 to +47 = 32 + (8 to 15): Uses the low 4 bits of the value as378the window size logarithm, and automatically accepts either379the zlib or gzip format.</p></li>380</ul>381<p>When decompressing a stream, the window size must not be smaller382than the size originally used to compress the stream; using a too-small383value may result in an <a class="reference internal" href="#zlib.error" title="zlib.error"><code class="xref py py-exc docutils literal notranslate"><span class="pre">error</span></code></a> exception. The default <em>wbits</em> value384corresponds to the largest window size and requires a zlib header and385trailer to be included.</p>386<p><em>bufsize</em> is the initial size of the buffer used to hold decompressed data. If387more space is required, the buffer size will be increased as needed, so you388don’t have to get this value exactly right; tuning it will only save a few calls389to <code class="xref c c-func docutils literal notranslate"><span class="pre">malloc()</span></code>.</p>390<div class="versionchanged">391<p><span class="versionmodified changed">Changed in version 3.6: </span><em>wbits</em> and <em>bufsize</em> can be used as keyword arguments.</p>392</div>393</dd></dl>394 395<dl class="py function">396<dt class="sig sig-object py" id="zlib.decompressobj">397<span class="sig-prename descclassname"><span class="pre">zlib.</span></span><span class="sig-name descname"><span class="pre">decompressobj</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">wbits=MAX_WBITS</span></span></em><span class="optional">[</span>, <em class="sig-param"><span class="n"><span class="pre">zdict</span></span></em><span class="optional">]</span><span class="sig-paren">)</span><a class="headerlink" href="#zlib.decompressobj" title="Link to this definition">¶</a></dt>398<dd><p>Returns a decompression object, to be used for decompressing data streams that399won’t fit into memory at once.</p>400<p>The <em>wbits</em> parameter controls the size of the history buffer (or the401“window size”), and what header and trailer format is expected. It has402the same meaning as <a class="reference external" href="#decompress-wbits">described for decompress()</a>.</p>403<p>The <em>zdict</em> parameter specifies a predefined compression dictionary. If404provided, this must be the same dictionary as was used by the compressor that405produced the data that is to be decompressed.</p>406<div class="admonition note">407<p class="admonition-title">Note</p>408<p>If <em>zdict</em> is a mutable object (such as a <a class="reference internal" href="stdtypes.html#bytearray" title="bytearray"><code class="xref py py-class docutils literal notranslate"><span class="pre">bytearray</span></code></a>), you must not409modify its contents between the call to <code class="xref py py-func docutils literal notranslate"><span class="pre">decompressobj()</span></code> and the first410call to the decompressor’s <code class="docutils literal notranslate"><span class="pre">decompress()</span></code> method.</p>411</div>412<div class="versionchanged">413<p><span class="versionmodified changed">Changed in version 3.3: </span>Added the <em>zdict</em> parameter.</p>414</div>415</dd></dl>416 417<p>Compression objects support the following methods:</p>418<dl class="py method">419<dt class="sig sig-object py" id="zlib.Compress.compress">420<span class="sig-prename descclassname"><span class="pre">Compress.</span></span><span class="sig-name descname"><span class="pre">compress</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">data</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#zlib.Compress.compress" title="Link to this definition">¶</a></dt>421<dd><p>Compress <em>data</em>, returning a bytes object containing compressed data for at least422part of the data in <em>data</em>. This data should be concatenated to the output423produced by any preceding calls to the <code class="xref py py-meth docutils literal notranslate"><span class="pre">compress()</span></code> method. Some input may424be kept in internal buffers for later processing.</p>425</dd></dl>426 427<dl class="py method">428<dt class="sig sig-object py" id="zlib.Compress.flush">429<span class="sig-prename descclassname"><span class="pre">Compress.</span></span><span class="sig-name descname"><span class="pre">flush</span></span><span class="sig-paren">(</span><span class="optional">[</span><em class="sig-param"><span class="n"><span class="pre">mode</span></span></em><span class="optional">]</span><span class="sig-paren">)</span><a class="headerlink" href="#zlib.Compress.flush" title="Link to this definition">¶</a></dt>430<dd><p>All pending input is processed, and a bytes object containing the remaining compressed431output is returned. <em>mode</em> can be selected from the constants432<a class="reference internal" href="#zlib.Z_NO_FLUSH" title="zlib.Z_NO_FLUSH"><code class="xref py py-const docutils literal notranslate"><span class="pre">Z_NO_FLUSH</span></code></a>, <a class="reference internal" href="#zlib.Z_PARTIAL_FLUSH" title="zlib.Z_PARTIAL_FLUSH"><code class="xref py py-const docutils literal notranslate"><span class="pre">Z_PARTIAL_FLUSH</span></code></a>, <a class="reference internal" href="#zlib.Z_SYNC_FLUSH" title="zlib.Z_SYNC_FLUSH"><code class="xref py py-const docutils literal notranslate"><span class="pre">Z_SYNC_FLUSH</span></code></a>,433<a class="reference internal" href="#zlib.Z_FULL_FLUSH" title="zlib.Z_FULL_FLUSH"><code class="xref py py-const docutils literal notranslate"><span class="pre">Z_FULL_FLUSH</span></code></a>, <a class="reference internal" href="#zlib.Z_BLOCK" title="zlib.Z_BLOCK"><code class="xref py py-const docutils literal notranslate"><span class="pre">Z_BLOCK</span></code></a>, or <a class="reference internal" href="#zlib.Z_FINISH" title="zlib.Z_FINISH"><code class="xref py py-const docutils literal notranslate"><span class="pre">Z_FINISH</span></code></a>,434defaulting to <code class="xref py py-const docutils literal notranslate"><span class="pre">Z_FINISH</span></code>. Except <code class="xref py py-const docutils literal notranslate"><span class="pre">Z_FINISH</span></code>, all constants435allow compressing further bytestrings of data, while <code class="xref py py-const docutils literal notranslate"><span class="pre">Z_FINISH</span></code> finishes the436compressed stream and prevents compressing any more data. After calling <code class="xref py py-meth docutils literal notranslate"><span class="pre">flush()</span></code>437with <em>mode</em> set to <code class="xref py py-const docutils literal notranslate"><span class="pre">Z_FINISH</span></code>, the <a class="reference internal" href="#zlib.compress" title="zlib.compress"><code class="xref py py-meth docutils literal notranslate"><span class="pre">compress()</span></code></a> method cannot be called again;438the only realistic action is to delete the object.</p>439</dd></dl>440 441<dl class="py method">442<dt class="sig sig-object py" id="zlib.Compress.copy">443<span class="sig-prename descclassname"><span class="pre">Compress.</span></span><span class="sig-name descname"><span class="pre">copy</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#zlib.Compress.copy" title="Link to this definition">¶</a></dt>444<dd><p>Returns a copy of the compression object. This can be used to efficiently445compress a set of data that share a common initial prefix.</p>446</dd></dl>447 448<div class="versionchanged">449<p><span class="versionmodified changed">Changed in version 3.8: </span>Added <a class="reference internal" href="copy.html#copy.copy" title="copy.copy"><code class="xref py py-func docutils literal notranslate"><span class="pre">copy.copy()</span></code></a> and <a class="reference internal" href="copy.html#copy.deepcopy" title="copy.deepcopy"><code class="xref py py-func docutils literal notranslate"><span class="pre">copy.deepcopy()</span></code></a> support to compression450objects.</p>451</div>452<p>Decompression objects support the following methods and attributes:</p>453<dl class="py attribute">454<dt class="sig sig-object py" id="zlib.Decompress.unused_data">455<span class="sig-prename descclassname"><span class="pre">Decompress.</span></span><span class="sig-name descname"><span class="pre">unused_data</span></span><a class="headerlink" href="#zlib.Decompress.unused_data" title="Link to this definition">¶</a></dt>456<dd><p>A bytes object which contains any bytes past the end of the compressed data. That is,457this remains <code class="docutils literal notranslate"><span class="pre">b""</span></code> until the last byte that contains compression data is458available. If the whole bytestring turned out to contain compressed data, this is459<code class="docutils literal notranslate"><span class="pre">b""</span></code>, an empty bytes object.</p>460</dd></dl>461 462<dl class="py attribute">463<dt class="sig sig-object py" id="zlib.Decompress.unconsumed_tail">464<span class="sig-prename descclassname"><span class="pre">Decompress.</span></span><span class="sig-name descname"><span class="pre">unconsumed_tail</span></span><a class="headerlink" href="#zlib.Decompress.unconsumed_tail" title="Link to this definition">¶</a></dt>465<dd><p>A bytes object that contains any data that was not consumed by the last466<a class="reference internal" href="#zlib.decompress" title="zlib.decompress"><code class="xref py py-meth docutils literal notranslate"><span class="pre">decompress()</span></code></a> call because it exceeded the limit for the uncompressed data467buffer. This data has not yet been seen by the zlib machinery, so you must feed468it (possibly with further data concatenated to it) back to a subsequent469<code class="xref py py-meth docutils literal notranslate"><span class="pre">decompress()</span></code> method call in order to get correct output.</p>470</dd></dl>471 472<dl class="py attribute">473<dt class="sig sig-object py" id="zlib.Decompress.eof">474<span class="sig-prename descclassname"><span class="pre">Decompress.</span></span><span class="sig-name descname"><span class="pre">eof</span></span><a class="headerlink" href="#zlib.Decompress.eof" title="Link to this definition">¶</a></dt>475<dd><p>A boolean indicating whether the end of the compressed data stream has been476reached.</p>477<p>This makes it possible to distinguish between a properly formed compressed478stream, and an incomplete or truncated one.</p>479<div class="versionadded">480<p><span class="versionmodified added">Added in version 3.3.</span></p>481</div>482</dd></dl>483 484<dl class="py method">485<dt class="sig sig-object py" id="zlib.Decompress.decompress">486<span class="sig-prename descclassname"><span class="pre">Decompress.</span></span><span class="sig-name descname"><span class="pre">decompress</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">data</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">max_length</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">0</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#zlib.Decompress.decompress" title="Link to this definition">¶</a></dt>487<dd><p>Decompress <em>data</em>, returning a bytes object containing the uncompressed data488corresponding to at least part of the data in <em>string</em>. This data should be489concatenated to the output produced by any preceding calls to the490<code class="xref py py-meth docutils literal notranslate"><span class="pre">decompress()</span></code> method. Some of the input data may be preserved in internal491buffers for later processing.</p>492<p>If the optional parameter <em>max_length</em> is non-zero then the return value will be493no longer than <em>max_length</em>. This may mean that not all of the compressed input494can be processed; and unconsumed data will be stored in the attribute495<a class="reference internal" href="#zlib.Decompress.unconsumed_tail" title="zlib.Decompress.unconsumed_tail"><code class="xref py py-attr docutils literal notranslate"><span class="pre">unconsumed_tail</span></code></a>. This bytestring must be passed to a subsequent call to496<code class="xref py py-meth docutils literal notranslate"><span class="pre">decompress()</span></code> if decompression is to continue. If <em>max_length</em> is zero497then the whole input is decompressed, and <code class="xref py py-attr docutils literal notranslate"><span class="pre">unconsumed_tail</span></code> is empty.</p>498<div class="versionchanged">499<p><span class="versionmodified changed">Changed in version 3.6: </span><em>max_length</em> can be used as a keyword argument.</p>500</div>501</dd></dl>502 503<dl class="py method">504<dt class="sig sig-object py" id="zlib.Decompress.flush">505<span class="sig-prename descclassname"><span class="pre">Decompress.</span></span><span class="sig-name descname"><span class="pre">flush</span></span><span class="sig-paren">(</span><span class="optional">[</span><em class="sig-param"><span class="n"><span class="pre">length</span></span></em><span class="optional">]</span><span class="sig-paren">)</span><a class="headerlink" href="#zlib.Decompress.flush" title="Link to this definition">¶</a></dt>506<dd><p>All pending input is processed, and a bytes object containing the remaining507uncompressed output is returned. After calling <code class="xref py py-meth docutils literal notranslate"><span class="pre">flush()</span></code>, the508<a class="reference internal" href="#zlib.decompress" title="zlib.decompress"><code class="xref py py-meth docutils literal notranslate"><span class="pre">decompress()</span></code></a> method cannot be called again; the only realistic action is509to delete the object.</p>510<p>The optional parameter <em>length</em> sets the initial size of the output buffer.</p>511</dd></dl>512 513<dl class="py method">514<dt class="sig sig-object py" id="zlib.Decompress.copy">515<span class="sig-prename descclassname"><span class="pre">Decompress.</span></span><span class="sig-name descname"><span class="pre">copy</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#zlib.Decompress.copy" title="Link to this definition">¶</a></dt>516<dd><p>Returns a copy of the decompression object. This can be used to save the state517of the decompressor midway through the data stream in order to speed up random518seeks into the stream at a future point.</p>519</dd></dl>520 521<div class="versionchanged">522<p><span class="versionmodified changed">Changed in version 3.8: </span>Added <a class="reference internal" href="copy.html#copy.copy" title="copy.copy"><code class="xref py py-func docutils literal notranslate"><span class="pre">copy.copy()</span></code></a> and <a class="reference internal" href="copy.html#copy.deepcopy" title="copy.deepcopy"><code class="xref py py-func docutils literal notranslate"><span class="pre">copy.deepcopy()</span></code></a> support to decompression523objects.</p>524</div>525<p>The following constants are available to configure compression and decompression526behavior:</p>527<dl class="py data">528<dt class="sig sig-object py" id="zlib.DEFLATED">529<span class="sig-prename descclassname"><span class="pre">zlib.</span></span><span class="sig-name descname"><span class="pre">DEFLATED</span></span><a class="headerlink" href="#zlib.DEFLATED" title="Link to this definition">¶</a></dt>530<dd><p>The deflate compression method.</p>531</dd></dl>532 533<dl class="py data">534<dt class="sig sig-object py" id="zlib.MAX_WBITS">535<span class="sig-prename descclassname"><span class="pre">zlib.</span></span><span class="sig-name descname"><span class="pre">MAX_WBITS</span></span><a class="headerlink" href="#zlib.MAX_WBITS" title="Link to this definition">¶</a></dt>536<dd><p>The maximum window size, expressed as a power of 2.537For example, if <code class="xref py py-const docutils literal notranslate"><span class="pre">MAX_WBITS</span></code> is <code class="docutils literal notranslate"><span class="pre">15</span></code> it results in a window size538of <code class="docutils literal notranslate"><span class="pre">32</span> <span class="pre">KiB</span></code>.</p>539</dd></dl>540 541<dl class="py data">542<dt class="sig sig-object py" id="zlib.DEF_MEM_LEVEL">543<span class="sig-prename descclassname"><span class="pre">zlib.</span></span><span class="sig-name descname"><span class="pre">DEF_MEM_LEVEL</span></span><a class="headerlink" href="#zlib.DEF_MEM_LEVEL" title="Link to this definition">¶</a></dt>544<dd><p>The default memory level for compression objects.</p>545</dd></dl>546 547<dl class="py data">548<dt class="sig sig-object py" id="zlib.DEF_BUF_SIZE">549<span class="sig-prename descclassname"><span class="pre">zlib.</span></span><span class="sig-name descname"><span class="pre">DEF_BUF_SIZE</span></span><a class="headerlink" href="#zlib.DEF_BUF_SIZE" title="Link to this definition">¶</a></dt>550<dd><p>The default buffer size for decompression operations.</p>551</dd></dl>552 553<dl class="py data">554<dt class="sig sig-object py" id="zlib.Z_NO_COMPRESSION">555<span class="sig-prename descclassname"><span class="pre">zlib.</span></span><span class="sig-name descname"><span class="pre">Z_NO_COMPRESSION</span></span><a class="headerlink" href="#zlib.Z_NO_COMPRESSION" title="Link to this definition">¶</a></dt>556<dd><p>Compression level <code class="docutils literal notranslate"><span class="pre">0</span></code>; no compression.</p>557<div class="versionadded">558<p><span class="versionmodified added">Added in version 3.6.</span></p>559</div>560</dd></dl>561 562<dl class="py data">563<dt class="sig sig-object py" id="zlib.Z_BEST_SPEED">564<span class="sig-prename descclassname"><span class="pre">zlib.</span></span><span class="sig-name descname"><span class="pre">Z_BEST_SPEED</span></span><a class="headerlink" href="#zlib.Z_BEST_SPEED" title="Link to this definition">¶</a></dt>565<dd><p>Compression level <code class="docutils literal notranslate"><span class="pre">1</span></code>; fastest and produces the least compression.</p>566</dd></dl>567 568<dl class="py data">569<dt class="sig sig-object py" id="zlib.Z_BEST_COMPRESSION">570<span class="sig-prename descclassname"><span class="pre">zlib.</span></span><span class="sig-name descname"><span class="pre">Z_BEST_COMPRESSION</span></span><a class="headerlink" href="#zlib.Z_BEST_COMPRESSION" title="Link to this definition">¶</a></dt>571<dd><p>Compression level <code class="docutils literal notranslate"><span class="pre">9</span></code>; slowest and produces the most compression.</p>572</dd></dl>573 574<dl class="py data">575<dt class="sig sig-object py" id="zlib.Z_DEFAULT_COMPRESSION">576<span class="sig-prename descclassname"><span class="pre">zlib.</span></span><span class="sig-name descname"><span class="pre">Z_DEFAULT_COMPRESSION</span></span><a class="headerlink" href="#zlib.Z_DEFAULT_COMPRESSION" title="Link to this definition">¶</a></dt>577<dd><p>Default compression level (<code class="docutils literal notranslate"><span class="pre">-1</span></code>); a compromise between speed and578compression. Currently equivalent to compression level <code class="docutils literal notranslate"><span class="pre">6</span></code>.</p>579</dd></dl>580 581<dl class="py data">582<dt class="sig sig-object py" id="zlib.Z_DEFAULT_STRATEGY">583<span class="sig-prename descclassname"><span class="pre">zlib.</span></span><span class="sig-name descname"><span class="pre">Z_DEFAULT_STRATEGY</span></span><a class="headerlink" href="#zlib.Z_DEFAULT_STRATEGY" title="Link to this definition">¶</a></dt>584<dd><p>Default compression strategy, for normal data.</p>585</dd></dl>586 587<dl class="py data">588<dt class="sig sig-object py" id="zlib.Z_FILTERED">589<span class="sig-prename descclassname"><span class="pre">zlib.</span></span><span class="sig-name descname"><span class="pre">Z_FILTERED</span></span><a class="headerlink" href="#zlib.Z_FILTERED" title="Link to this definition">¶</a></dt>590<dd><p>Compression strategy for data produced by a filter (or predictor).</p>591</dd></dl>592 593<dl class="py data">594<dt class="sig sig-object py" id="zlib.Z_HUFFMAN_ONLY">595<span class="sig-prename descclassname"><span class="pre">zlib.</span></span><span class="sig-name descname"><span class="pre">Z_HUFFMAN_ONLY</span></span><a class="headerlink" href="#zlib.Z_HUFFMAN_ONLY" title="Link to this definition">¶</a></dt>596<dd><p>Compression strategy that forces Huffman coding only.</p>597</dd></dl>598 599<dl class="py data">600<dt class="sig sig-object py" id="zlib.Z_RLE">601<span class="sig-prename descclassname"><span class="pre">zlib.</span></span><span class="sig-name descname"><span class="pre">Z_RLE</span></span><a class="headerlink" href="#zlib.Z_RLE" title="Link to this definition">¶</a></dt>602<dd><p>Compression strategy that limits match distances to one (run-length encoding).</p>603<p>This constant is only available if Python was compiled with zlib6041.2.0.1 or greater.</p>605<div class="versionadded">606<p><span class="versionmodified added">Added in version 3.6.</span></p>607</div>608</dd></dl>609 610<dl class="py data">611<dt class="sig sig-object py" id="zlib.Z_FIXED">612<span class="sig-prename descclassname"><span class="pre">zlib.</span></span><span class="sig-name descname"><span class="pre">Z_FIXED</span></span><a class="headerlink" href="#zlib.Z_FIXED" title="Link to this definition">¶</a></dt>613<dd><p>Compression strategy that prevents the use of dynamic Huffman codes.</p>614<p>This constant is only available if Python was compiled with zlib6151.2.2.2 or greater.</p>616<div class="versionadded">617<p><span class="versionmodified added">Added in version 3.6.</span></p>618</div>619</dd></dl>620 621<dl class="py data">622<dt class="sig sig-object py" id="zlib.Z_NO_FLUSH">623<span class="sig-prename descclassname"><span class="pre">zlib.</span></span><span class="sig-name descname"><span class="pre">Z_NO_FLUSH</span></span><a class="headerlink" href="#zlib.Z_NO_FLUSH" title="Link to this definition">¶</a></dt>624<dd><p>Flush mode <code class="docutils literal notranslate"><span class="pre">0</span></code>. No special flushing behavior.</p>625<div class="versionadded">626<p><span class="versionmodified added">Added in version 3.6.</span></p>627</div>628</dd></dl>629 630<dl class="py data">631<dt class="sig sig-object py" id="zlib.Z_PARTIAL_FLUSH">632<span class="sig-prename descclassname"><span class="pre">zlib.</span></span><span class="sig-name descname"><span class="pre">Z_PARTIAL_FLUSH</span></span><a class="headerlink" href="#zlib.Z_PARTIAL_FLUSH" title="Link to this definition">¶</a></dt>633<dd><p>Flush mode <code class="docutils literal notranslate"><span class="pre">1</span></code>. Flush as much output as possible.</p>634</dd></dl>635 636<dl class="py data">637<dt class="sig sig-object py" id="zlib.Z_SYNC_FLUSH">638<span class="sig-prename descclassname"><span class="pre">zlib.</span></span><span class="sig-name descname"><span class="pre">Z_SYNC_FLUSH</span></span><a class="headerlink" href="#zlib.Z_SYNC_FLUSH" title="Link to this definition">¶</a></dt>639<dd><p>Flush mode <code class="docutils literal notranslate"><span class="pre">2</span></code>. All output is flushed and the output is aligned to a byte boundary.</p>640</dd></dl>641 642<dl class="py data">643<dt class="sig sig-object py" id="zlib.Z_FULL_FLUSH">644<span class="sig-prename descclassname"><span class="pre">zlib.</span></span><span class="sig-name descname"><span class="pre">Z_FULL_FLUSH</span></span><a class="headerlink" href="#zlib.Z_FULL_FLUSH" title="Link to this definition">¶</a></dt>645<dd><p>Flush mode <code class="docutils literal notranslate"><span class="pre">3</span></code>. All output is flushed and the compression state is reset.</p>646</dd></dl>647 648<dl class="py data">649<dt class="sig sig-object py" id="zlib.Z_FINISH">650<span class="sig-prename descclassname"><span class="pre">zlib.</span></span><span class="sig-name descname"><span class="pre">Z_FINISH</span></span><a class="headerlink" href="#zlib.Z_FINISH" title="Link to this definition">¶</a></dt>651<dd><p>Flush mode <code class="docutils literal notranslate"><span class="pre">4</span></code>. All pending input is processed, no more input is expected.</p>652</dd></dl>653 654<dl class="py data">655<dt class="sig sig-object py" id="zlib.Z_BLOCK">656<span class="sig-prename descclassname"><span class="pre">zlib.</span></span><span class="sig-name descname"><span class="pre">Z_BLOCK</span></span><a class="headerlink" href="#zlib.Z_BLOCK" title="Link to this definition">¶</a></dt>657<dd><p>Flush mode <code class="docutils literal notranslate"><span class="pre">5</span></code>. A deflate block is completed and emitted.</p>658<p>This constant is only available if Python was compiled with zlib6591.2.2.2 or greater.</p>660<div class="versionadded">661<p><span class="versionmodified added">Added in version 3.6.</span></p>662</div>663</dd></dl>664 665<dl class="py data">666<dt class="sig sig-object py" id="zlib.Z_TREES">667<span class="sig-prename descclassname"><span class="pre">zlib.</span></span><span class="sig-name descname"><span class="pre">Z_TREES</span></span><a class="headerlink" href="#zlib.Z_TREES" title="Link to this definition">¶</a></dt>668<dd><p>Flush mode <code class="docutils literal notranslate"><span class="pre">6</span></code>, for inflate operations. Instructs inflate to return when669it gets to the next deflate block boundary.</p>670<p>This constant is only available if Python was compiled with zlib6711.2.3.4 or greater.</p>672<div class="versionadded">673<p><span class="versionmodified added">Added in version 3.6.</span></p>674</div>675</dd></dl>676 677<p>Information about the version of the zlib library in use is available through678the following constants:</p>679<dl class="py data">680<dt class="sig sig-object py" id="zlib.ZLIB_VERSION">681<span class="sig-prename descclassname"><span class="pre">zlib.</span></span><span class="sig-name descname"><span class="pre">ZLIB_VERSION</span></span><a class="headerlink" href="#zlib.ZLIB_VERSION" title="Link to this definition">¶</a></dt>682<dd><p>The version string of the zlib library that was used for building the module.683This may be different from the zlib library actually used at runtime, which684is available as <a class="reference internal" href="#zlib.ZLIB_RUNTIME_VERSION" title="zlib.ZLIB_RUNTIME_VERSION"><code class="xref py py-const docutils literal notranslate"><span class="pre">ZLIB_RUNTIME_VERSION</span></code></a>.</p>685</dd></dl>686 687<dl class="py data">688<dt class="sig sig-object py" id="zlib.ZLIB_RUNTIME_VERSION">689<span class="sig-prename descclassname"><span class="pre">zlib.</span></span><span class="sig-name descname"><span class="pre">ZLIB_RUNTIME_VERSION</span></span><a class="headerlink" href="#zlib.ZLIB_RUNTIME_VERSION" title="Link to this definition">¶</a></dt>690<dd><p>The version string of the zlib library actually loaded by the interpreter.</p>691<div class="versionadded">692<p><span class="versionmodified added">Added in version 3.3.</span></p>693</div>694</dd></dl>695 696<dl class="py data">697<dt class="sig sig-object py" id="zlib.ZLIBNG_VERSION">698<span class="sig-prename descclassname"><span class="pre">zlib.</span></span><span class="sig-name descname"><span class="pre">ZLIBNG_VERSION</span></span><a class="headerlink" href="#zlib.ZLIBNG_VERSION" title="Link to this definition">¶</a></dt>699<dd><p>The version string of the zlib-ng library that was used for building the700module if zlib-ng was used. When present, the <a class="reference internal" href="#zlib.ZLIB_VERSION" title="zlib.ZLIB_VERSION"><code class="xref py py-data docutils literal notranslate"><span class="pre">ZLIB_VERSION</span></code></a> and701<a class="reference internal" href="#zlib.ZLIB_RUNTIME_VERSION" title="zlib.ZLIB_RUNTIME_VERSION"><code class="xref py py-data docutils literal notranslate"><span class="pre">ZLIB_RUNTIME_VERSION</span></code></a> constants reflect the version of the zlib API702provided by zlib-ng.</p>703<p>If zlib-ng was not used to build the module, this constant will be absent.</p>704<div class="versionadded">705<p><span class="versionmodified added">Added in version 3.14.</span></p>706</div>707</dd></dl>708 709<div class="admonition seealso">710<p class="admonition-title">See also</p>711<dl class="simple">712<dt>Module <a class="reference internal" href="gzip.html#module-gzip" title="gzip: Interfaces for gzip compression and decompression using file objects."><code class="xref py py-mod docutils literal notranslate"><span class="pre">gzip</span></code></a></dt><dd><p>Reading and writing <strong class="program">gzip</strong>-format files.</p>713</dd>714<dt><a class="reference external" href="https://www.zlib.net">https://www.zlib.net</a></dt><dd><p>The zlib library home page.</p>715</dd>716<dt><a class="reference external" href="https://www.zlib.net/manual.html">https://www.zlib.net/manual.html</a></dt><dd><p>The zlib manual explains the semantics and usage of the library’s many717functions.</p>718</dd>719</dl>720<p>In case gzip (de)compression is a bottleneck, the <a class="reference external" href="https://github.com/pycompression/python-isal">python-isal</a>721package speeds up (de)compression with a mostly compatible API.</p>722</div>723</section>724 725 726 <div class="clearer"></div>727 </div>728 </div>729 </div>730 <div class="sphinxsidebar" role="navigation" aria-label="Main">731 <div class="sphinxsidebarwrapper">732 <div>733 <h4>Previous topic</h4>734 <p class="topless"><a href="compression.zstd.html"735 title="previous chapter"><code class="xref py py-mod docutils literal notranslate"><span class="pre">compression.zstd</span></code> — Compression compatible with the Zstandard format</a></p>736 </div>737 <div>738 <h4>Next topic</h4>739 <p class="topless"><a href="gzip.html"740 title="next chapter"><code class="xref py py-mod docutils literal notranslate"><span class="pre">gzip</span></code> — Support for <strong class="program">gzip</strong> files</a></p>741 </div>742 <script>743 document.addEventListener('DOMContentLoaded', () => {744 const title = document.querySelector('meta[property="og:title"]').content;745 const elements = document.querySelectorAll('.improvepage');746 const pageurl = window.location.href.split('?')[0];747 elements.forEach(element => {748 const url = new URL(element.href.split('?')[0].replace("-nojs", ""));749 url.searchParams.set('pagetitle', title);750 url.searchParams.set('pageurl', pageurl);751 url.searchParams.set('pagesource', "library/zlib.rst");752 element.href = url.toString();753 });754 });755 </script>756 <div role="note" aria-label="source link">757 <h3>This page</h3>758 <ul class="this-page-menu">759 <li><a href="../bugs.html">Report a bug</a></li>760 <li><a class="improvepage" href="../improve-page-nojs.html">Improve this page</a></li>761 <li>762 <a href="https://github.com/python/cpython/blob/main/Doc/library/zlib.rst?plain=1"763 rel="nofollow">Show source764 </a>765 </li>766 767 </ul>768 </div>769 </div>770<div id="sidebarbutton" title="Collapse sidebar">771<span>«</span>772</div>773 774 </div>775 <div class="clearer"></div>776 </div> 777 <div class="related" role="navigation" aria-label="Related">778 <h3>Navigation</h3>779 <ul>780 <li class="right" style="margin-right: 10px">781 <a href="../genindex.html" title="General Index"782 >index</a></li>783 <li class="right" >784 <a href="../py-modindex.html" title="Python Module Index"785 >modules</a> |</li>786 <li class="right" >787 <a href="gzip.html" title="gzip — Support for gzip files"788 >next</a> |</li>789 <li class="right" >790 <a href="compression.zstd.html" title="compression.zstd — Compression compatible with the Zstandard format"791 >previous</a> |</li>792 793 <li><img src="../_static/py.svg" alt="Python logo" style="vertical-align: middle; 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