[OpenSPARC-T2-DV] / tools / src / nas,5.n2.os.2 / lib / python / html / python / lib / node406.html

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<html>
<head>
<link rel="STYLESHEET" href="lib.css" type='text/css' />
<link rel="SHORTCUT ICON" href="../icons/pyfav.png" type="image/png" />
<link rel='start' href='../index.html' title='Python Documentation Index' />
<link rel="first" href="lib.html" title='Python Library Reference' />
<link rel='contents' href='contents.html' title="Contents" />
<link rel='index' href='genindex.html' title='Index' />
<link rel='last' href='about.html' title='About this document...' />
<link rel='help' href='about.html' title='About this document...' />
<link rel="next" href="node407.html" />
<link rel="prev" href="module-bz2.html" />
<link rel="parent" href="module-bz2.html" />
<link rel="next" href="node407.html" />
<meta name='aesop' content='information' />
<title>7.17.1 (De)compression of files</title>
</head>
<body>
<DIV CLASS="navigation">
<div id='top-navigation-panel' xml:id='top-navigation-panel'>
<table align="center" width="100%" cellpadding="0" cellspacing="2">
<tr>
<td class='online-navigation'><a rel="prev" title="7.17 bz2  "
  href="module-bz2.html"><img src='../icons/previous.png'
  border='0' height='32'  alt='Previous Page' width='32' /></A></td>
<td class='online-navigation'><a rel="parent" title="7.17 bz2  "
  href="module-bz2.html"><img src='../icons/up.png'
  border='0' height='32'  alt='Up One Level' width='32' /></A></td>
<td class='online-navigation'><a rel="next" title="7.17.2 Sequential (de)compression"
  href="node407.html"><img src='../icons/next.png'
  border='0' height='32'  alt='Next Page' width='32' /></A></td>
<td align="center" width="100%">Python Library Reference</td>
<td class='online-navigation'><a rel="contents" title="Table of Contents"
  href="contents.html"><img src='../icons/contents.png'
  border='0' height='32'  alt='Contents' width='32' /></A></td>
<td class='online-navigation'><a href="modindex.html" title="Module Index"><img src='../icons/modules.png'
  border='0' height='32'  alt='Module Index' width='32' /></a></td>
<td class='online-navigation'><a rel="index" title="Index"
  href="genindex.html"><img src='../icons/index.png'
  border='0' height='32'  alt='Index' width='32' /></A></td>
</tr></table>
<div class='online-navigation'>
<b class="navlabel">Previous:</b>
<a class="sectref" rel="prev" href="module-bz2.html">7.17 bz2  </A>
<b class="navlabel">Up:</b>
<a class="sectref" rel="parent" href="module-bz2.html">7.17 bz2  </A>
<b class="navlabel">Next:</b>
<a class="sectref" rel="next" href="node407.html">7.17.2 Sequential (de)compression</A>
</div>
<hr /></div>
</DIV>
<!--End of Navigation Panel-->

<H2><A NAME="SECTION0091710000000000000000">
7.17.1 (De)compression of files</A>
</H2>

<P>
Handling of compressed files is offered by the <tt class="class">BZ2File</tt> class.

<P>
<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
  <td><nobr><b><span class="typelabel">class</span>&nbsp;<tt id='l2h-2833' xml:id='l2h-2833' class="class">BZ2File</tt></b>(</nobr></td>
  <td><var>filename</var><big>[</big><var>, mode</var><big>[</big><var>,
                           buffering</var><big>[</big><var>, compresslevel</var><big>]</big><var></var><big>]</big><var></var><big>]</big><var></var>)</td></tr></table></dt>
<dd>
Open a bz2 file. Mode can be either <code>'r'</code> or <code>'w'</code>, for reading 
(default) or writing. When opened for writing, the file will be created if
it doesn't exist, and truncated otherwise. If <var>buffering</var> is given,
<code>0</code> means unbuffered, and larger numbers specify the buffer size;
the default is <code>0</code>. If
<var>compresslevel</var> is given, it must be a number between <code>1</code> and
<code>9</code>; the default is <code>9</code>.
Add a "<tt class="character">U</tt>" to mode to open the file for input with universal newline
support. Any line ending in the input file will be seen as a
"<tt class="character">&#92;n</tt>" in Python.  Also, a file so opened gains the
attribute <tt class="member">newlines</tt>; the value for this attribute is one of
<code>None</code> (no newline read yet), <code>'&#92;r'</code>, <code>'&#92;n'</code>,
<code>'&#92;r&#92;n'</code> or a tuple containing all the newline types
seen. Universal newlines are available only when reading.
Instances support iteration in the same way as normal <tt class="class">file</tt>
instances.
</dl>

<P>
<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
  <td><nobr><b><tt id='l2h-2834' xml:id='l2h-2834' class="method">close</tt></b>(</nobr></td>
  <td><var></var>)</td></tr></table></dt>
<dd>
Close the file. Sets data attribute <tt class="member">closed</tt> to true. A closed file
cannot be used for further I/O operations. <tt class="method">close()</tt> may be called
more than once without error.
</dl>

<P>
<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
  <td><nobr><b><tt id='l2h-2835' xml:id='l2h-2835' class="method">read</tt></b>(</nobr></td>
  <td><var></var><big>[</big><var>size</var><big>]</big><var></var>)</td></tr></table></dt>
<dd>
Read at most <var>size</var> uncompressed bytes, returned as a string. If the
<var>size</var> argument is negative or omitted, read until EOF is reached.
</dl>

<P>
<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
  <td><nobr><b><tt id='l2h-2836' xml:id='l2h-2836' class="method">readline</tt></b>(</nobr></td>
  <td><var></var><big>[</big><var>size</var><big>]</big><var></var>)</td></tr></table></dt>
<dd>
Return the next line from the file, as a string, retaining newline.
A non-negative <var>size</var> argument limits the maximum number of bytes to
return (an incomplete line may be returned then). Return an empty
string at EOF.
</dl>

<P>
<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
  <td><nobr><b><tt id='l2h-2837' xml:id='l2h-2837' class="method">readlines</tt></b>(</nobr></td>
  <td><var></var><big>[</big><var>size</var><big>]</big><var></var>)</td></tr></table></dt>
<dd>
Return a list of lines read. The optional <var>size</var> argument, if given,
is an approximate bound on the total number of bytes in the lines returned.
</dl>

<P>
<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
  <td><nobr><b><tt id='l2h-2838' xml:id='l2h-2838' class="method">xreadlines</tt></b>(</nobr></td>
  <td><var></var>)</td></tr></table></dt>
<dd>
For backward compatibility. <tt class="class">BZ2File</tt> objects now include the
performance optimizations previously implemented in the
<tt class="module">xreadlines</tt> module.
<div class="versionnote"><b>Deprecated since release 2.3.</b>
This exists only for compatibility with the method by
                 this name on <tt class="class">file</tt> objects, which is
                 deprecated.  Use <code>for line in file</code> instead.</div><p></p>
</dl>

<P>
<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
  <td><nobr><b><tt id='l2h-2839' xml:id='l2h-2839' class="method">seek</tt></b>(</nobr></td>
  <td><var>offset</var><big>[</big><var>, whence</var><big>]</big><var></var>)</td></tr></table></dt>
<dd>
Move to new file position. Argument <var>offset</var> is a byte count. Optional
argument <var>whence</var> defaults to <code>0</code> (offset from start of file,
offset should be <code>&gt;= 0</code>); other values are <code>1</code> (move relative to
current position, positive or negative), and <code>2</code> (move relative to end
of file, usually negative, although many platforms allow seeking beyond
the end of a file).

<P>
Note that seeking of bz2 files is emulated, and depending on the parameters
the operation may be extremely slow.
</dl>

<P>
<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
  <td><nobr><b><tt id='l2h-2840' xml:id='l2h-2840' class="method">tell</tt></b>(</nobr></td>
  <td><var></var>)</td></tr></table></dt>
<dd>
Return the current file position, an integer (may be a long integer).
</dl>

<P>
<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
  <td><nobr><b><tt id='l2h-2841' xml:id='l2h-2841' class="method">write</tt></b>(</nobr></td>
  <td><var>data</var>)</td></tr></table></dt>
<dd>
Write string <var>data</var> to file. Note that due to buffering, <tt class="method">close()</tt>
may be needed before the file on disk reflects the data written.
</dl>

<P>
<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
  <td><nobr><b><tt id='l2h-2842' xml:id='l2h-2842' class="method">writelines</tt></b>(</nobr></td>
  <td><var>sequence_of_strings</var>)</td></tr></table></dt>
<dd>
Write the sequence of strings to the file. Note that newlines are not added.
The sequence can be any iterable object producing strings. This is equivalent
to calling write() for each string.
</dl>

<P>

<DIV CLASS="navigation">
<div class='online-navigation'>
<p></p><hr />
<table align="center" width="100%" cellpadding="0" cellspacing="2">
<tr>
<td class='online-navigation'><a rel="prev" title="7.17 bz2  "
  href="module-bz2.html"><img src='../icons/previous.png'
  border='0' height='32'  alt='Previous Page' width='32' /></A></td>
<td class='online-navigation'><a rel="parent" title="7.17 bz2  "
  href="module-bz2.html"><img src='../icons/up.png'
  border='0' height='32'  alt='Up One Level' width='32' /></A></td>
<td class='online-navigation'><a rel="next" title="7.17.2 Sequential (de)compression"
  href="node407.html"><img src='../icons/next.png'
  border='0' height='32'  alt='Next Page' width='32' /></A></td>
<td align="center" width="100%">Python Library Reference</td>
<td class='online-navigation'><a rel="contents" title="Table of Contents"
  href="contents.html"><img src='../icons/contents.png'
  border='0' height='32'  alt='Contents' width='32' /></A></td>
<td class='online-navigation'><a href="modindex.html" title="Module Index"><img src='../icons/modules.png'
  border='0' height='32'  alt='Module Index' width='32' /></a></td>
<td class='online-navigation'><a rel="index" title="Index"
  href="genindex.html"><img src='../icons/index.png'
  border='0' height='32'  alt='Index' width='32' /></A></td>
</tr></table>
<div class='online-navigation'>
<b class="navlabel">Previous:</b>
<a class="sectref" rel="prev" href="module-bz2.html">7.17 bz2  </A>
<b class="navlabel">Up:</b>
<a class="sectref" rel="parent" href="module-bz2.html">7.17 bz2  </A>
<b class="navlabel">Next:</b>
<a class="sectref" rel="next" href="node407.html">7.17.2 Sequential (de)compression</A>
</div>
</div>
<hr />
<span class="release-info">Release 2.4.2, documentation updated on 28 September 2005.</span>
</DIV>
<!--End of Navigation Panel-->
<ADDRESS>
See <i><a href="about.html">About this document...</a></i> for information on suggesting changes.
</ADDRESS>
</BODY>
</HTML>
Commit	Line	Data
86530b38 AT	1	<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
	2	<html>
	3	<head>
	4	<link rel="STYLESHEET" href="lib.css" type='text/css' />
	5	<link rel="SHORTCUT ICON" href="../icons/pyfav.png" type="image/png" />
	6	<link rel='start' href='../index.html' title='Python Documentation Index' />
	7	<link rel="first" href="lib.html" title='Python Library Reference' />
	8	<link rel='contents' href='contents.html' title="Contents" />
	9	<link rel='index' href='genindex.html' title='Index' />
	10	<link rel='last' href='about.html' title='About this document...' />
	11	<link rel='help' href='about.html' title='About this document...' />
	12	<link rel="next" href="node407.html" />
	13	<link rel="prev" href="module-bz2.html" />
	14	<link rel="parent" href="module-bz2.html" />
	15	<link rel="next" href="node407.html" />
	16	<meta name='aesop' content='information' />
	17	<title>7.17.1 (De)compression of files</title>
	18	</head>
	19	<body>
	20	<DIV CLASS="navigation">
	21	<div id='top-navigation-panel' xml:id='top-navigation-panel'>
	22	<table align="center" width="100%" cellpadding="0" cellspacing="2">
	23	<tr>
	24	<td class='online-navigation'><a rel="prev" title="7.17 bz2 "
	25	href="module-bz2.html"><img src='../icons/previous.png'
	26	border='0' height='32' alt='Previous Page' width='32' /></A></td>
	27	<td class='online-navigation'><a rel="parent" title="7.17 bz2 "
	28	href="module-bz2.html"><img src='../icons/up.png'
	29	border='0' height='32' alt='Up One Level' width='32' /></A></td>
	30	<td class='online-navigation'><a rel="next" title="7.17.2 Sequential (de)compression"
	31	href="node407.html"><img src='../icons/next.png'
	32	border='0' height='32' alt='Next Page' width='32' /></A></td>
	33	<td align="center" width="100%">Python Library Reference</td>
	34	<td class='online-navigation'><a rel="contents" title="Table of Contents"
	35	href="contents.html"><img src='../icons/contents.png'
	36	border='0' height='32' alt='Contents' width='32' /></A></td>
	37	<td class='online-navigation'><a href="modindex.html" title="Module Index"><img src='../icons/modules.png'
	38	border='0' height='32' alt='Module Index' width='32' /></a></td>
	39	<td class='online-navigation'><a rel="index" title="Index"
	40	href="genindex.html"><img src='../icons/index.png'
	41	border='0' height='32' alt='Index' width='32' /></A></td>
	42	</tr></table>
	43	<div class='online-navigation'>
	44	<b class="navlabel">Previous:</b>
	45	<a class="sectref" rel="prev" href="module-bz2.html">7.17 bz2 </A>
	46	<b class="navlabel">Up:</b>
	47	<a class="sectref" rel="parent" href="module-bz2.html">7.17 bz2 </A>
	48	<b class="navlabel">Next:</b>
	49	<a class="sectref" rel="next" href="node407.html">7.17.2 Sequential (de)compression</A>
	50	</div>
	51	<hr /></div>
	52	</DIV>
	53	<!--End of Navigation Panel-->
	54
	55	<H2><A NAME="SECTION0091710000000000000000">
	56	7.17.1 (De)compression of files</A>
	57	</H2>
	58
	59	<P>
	60	Handling of compressed files is offered by the <tt class="class">BZ2File</tt> class.
	61
	62	<P>
	63	<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
	64	<td><nobr><b><span class="typelabel">class</span> <tt id='l2h-2833' xml:id='l2h-2833' class="class">BZ2File</tt></b>(</nobr></td>
65	<td><var>filename</var><big>[</big><var>, mode</var><big>[</big><var>,
66	buffering</var><big>[</big><var>, compresslevel</var><big>]</big><var></var><big>]</big><var></var><big>]</big><var></var>)</td></tr></table></dt>
67	<dd>
68	Open a bz2 file. Mode can be either <code>'r'</code> or <code>'w'</code>, for reading
69	(default) or writing. When opened for writing, the file will be created if
70	it doesn't exist, and truncated otherwise. If <var>buffering</var> is given,
71	<code>0</code> means unbuffered, and larger numbers specify the buffer size;
72	the default is <code>0</code>. If
73	<var>compresslevel</var> is given, it must be a number between <code>1</code> and
74	<code>9</code>; the default is <code>9</code>.
75	Add a "<tt class="character">U</tt>" to mode to open the file for input with universal newline
76	support. Any line ending in the input file will be seen as a
77	"<tt class="character">\n</tt>" in Python. Also, a file so opened gains the
78	attribute <tt class="member">newlines</tt>; the value for this attribute is one of
79	<code>None</code> (no newline read yet), <code>'\r'</code>, <code>'\n'</code>,
80	<code>'\r\n'</code> or a tuple containing all the newline types
81	seen. Universal newlines are available only when reading.
82	Instances support iteration in the same way as normal <tt class="class">file</tt>
83	instances.
84	</dl>
85
86	<P>
87	<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
88	<td><nobr><b><tt id='l2h-2834' xml:id='l2h-2834' class="method">close</tt></b>(</nobr></td>
89	<td><var></var>)</td></tr></table></dt>
90	<dd>
91	Close the file. Sets data attribute <tt class="member">closed</tt> to true. A closed file
92	cannot be used for further I/O operations. <tt class="method">close()</tt> may be called
93	more than once without error.
94	</dl>
95
96	<P>
97	<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
98	<td><nobr><b><tt id='l2h-2835' xml:id='l2h-2835' class="method">read</tt></b>(</nobr></td>
99	<td><var></var><big>[</big><var>size</var><big>]</big><var></var>)</td></tr></table></dt>
100	<dd>
101	Read at most <var>size</var> uncompressed bytes, returned as a string. If the
102	<var>size</var> argument is negative or omitted, read until EOF is reached.
103	</dl>
104
105	<P>
106	<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
107	<td><nobr><b><tt id='l2h-2836' xml:id='l2h-2836' class="method">readline</tt></b>(</nobr></td>
108	<td><var></var><big>[</big><var>size</var><big>]</big><var></var>)</td></tr></table></dt>
109	<dd>
110	Return the next line from the file, as a string, retaining newline.
111	A non-negative <var>size</var> argument limits the maximum number of bytes to
112	return (an incomplete line may be returned then). Return an empty
113	string at EOF.
114	</dl>
115
116	<P>
117	<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
118	<td><nobr><b><tt id='l2h-2837' xml:id='l2h-2837' class="method">readlines</tt></b>(</nobr></td>
119	<td><var></var><big>[</big><var>size</var><big>]</big><var></var>)</td></tr></table></dt>
120	<dd>
121	Return a list of lines read. The optional <var>size</var> argument, if given,
122	is an approximate bound on the total number of bytes in the lines returned.
123	</dl>
124
125	<P>
126	<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
127	<td><nobr><b><tt id='l2h-2838' xml:id='l2h-2838' class="method">xreadlines</tt></b>(</nobr></td>
128	<td><var></var>)</td></tr></table></dt>
129	<dd>
130	For backward compatibility. <tt class="class">BZ2File</tt> objects now include the
131	performance optimizations previously implemented in the
132	<tt class="module">xreadlines</tt> module.
133	<div class="versionnote"><b>Deprecated since release 2.3.</b>
134	This exists only for compatibility with the method by
135	this name on <tt class="class">file</tt> objects, which is
136	deprecated. Use <code>for line in file</code> instead.</div><p></p>
137	</dl>
138
139	<P>
140	<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
141	<td><nobr><b><tt id='l2h-2839' xml:id='l2h-2839' class="method">seek</tt></b>(</nobr></td>
142	<td><var>offset</var><big>[</big><var>, whence</var><big>]</big><var></var>)</td></tr></table></dt>
143	<dd>
144	Move to new file position. Argument <var>offset</var> is a byte count. Optional
145	argument <var>whence</var> defaults to <code>0</code> (offset from start of file,
146	offset should be <code>>= 0</code>); other values are <code>1</code> (move relative to
147	current position, positive or negative), and <code>2</code> (move relative to end
148	of file, usually negative, although many platforms allow seeking beyond
149	the end of a file).
150
151	<P>
152	Note that seeking of bz2 files is emulated, and depending on the parameters
153	the operation may be extremely slow.
154	</dl>
155
156	<P>
157	<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
158	<td><nobr><b><tt id='l2h-2840' xml:id='l2h-2840' class="method">tell</tt></b>(</nobr></td>
159	<td><var></var>)</td></tr></table></dt>
160	<dd>
161	Return the current file position, an integer (may be a long integer).
162	</dl>
163
164	<P>
165	<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
166	<td><nobr><b><tt id='l2h-2841' xml:id='l2h-2841' class="method">write</tt></b>(</nobr></td>
167	<td><var>data</var>)</td></tr></table></dt>
168	<dd>
169	Write string <var>data</var> to file. Note that due to buffering, <tt class="method">close()</tt>
170	may be needed before the file on disk reflects the data written.
171	</dl>
172
173	<P>
174	<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
175	<td><nobr><b><tt id='l2h-2842' xml:id='l2h-2842' class="method">writelines</tt></b>(</nobr></td>
176	<td><var>sequence_of_strings</var>)</td></tr></table></dt>
177	<dd>
178	Write the sequence of strings to the file. Note that newlines are not added.
179	The sequence can be any iterable object producing strings. This is equivalent
180	to calling write() for each string.
181	</dl>
182
183	<P>
184
185	<DIV CLASS="navigation">
186	<div class='online-navigation'>
187	<p></p><hr />
188	<table align="center" width="100%" cellpadding="0" cellspacing="2">
189	<tr>
190	<td class='online-navigation'><a rel="prev" title="7.17 bz2 "
191	href="module-bz2.html"><img src='../icons/previous.png'
192	border='0' height='32' alt='Previous Page' width='32' /></A></td>
193	<td class='online-navigation'><a rel="parent" title="7.17 bz2 "
194	href="module-bz2.html"><img src='../icons/up.png'
195	border='0' height='32' alt='Up One Level' width='32' /></A></td>
196	<td class='online-navigation'><a rel="next" title="7.17.2 Sequential (de)compression"
197	href="node407.html"><img src='../icons/next.png'
198	border='0' height='32' alt='Next Page' width='32' /></A></td>
199	<td align="center" width="100%">Python Library Reference</td>
200	<td class='online-navigation'><a rel="contents" title="Table of Contents"
201	href="contents.html"><img src='../icons/contents.png'
202	border='0' height='32' alt='Contents' width='32' /></A></td>
203	<td class='online-navigation'><a href="modindex.html" title="Module Index"><img src='../icons/modules.png'
204	border='0' height='32' alt='Module Index' width='32' /></a></td>
205	<td class='online-navigation'><a rel="index" title="Index"
206	href="genindex.html"><img src='../icons/index.png'
207	border='0' height='32' alt='Index' width='32' /></A></td>
208	</tr></table>
209	<div class='online-navigation'>
210	<b class="navlabel">Previous:</b>
211	<a class="sectref" rel="prev" href="module-bz2.html">7.17 bz2 </A>
212	<b class="navlabel">Up:</b>
213	<a class="sectref" rel="parent" href="module-bz2.html">7.17 bz2 </A>
214	<b class="navlabel">Next:</b>
215	<a class="sectref" rel="next" href="node407.html">7.17.2 Sequential (de)compression</A>
216	</div>
217	</div>
218	<hr />
219	<span class="release-info">Release 2.4.2, documentation updated on 28 September 2005.</span>
220	</DIV>
221	<!--End of Navigation Panel-->
222	<ADDRESS>
223	See <i><a href="about.html">About this document...</a></i> for information on suggesting changes.
224	</ADDRESS>
225	</BODY>
226	</HTML>