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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> | |
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219 | <span class="release-info">Release 2.4.2, documentation updated on 28 September 2005.</span> | |
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