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| 55 | <H2><A NAME="SECTION0081020000000000000000"></A><A NAME="datetime-timedelta"></A> |
| 56 | <BR> |
| 57 | 6.10.2 <tt class="class">timedelta</tt> Objects |
| 58 | </H2> |
| 59 | |
| 60 | <P> |
| 61 | A <tt class="class">timedelta</tt> object represents a duration, the difference |
| 62 | between two dates or times. |
| 63 | |
| 64 | <P> |
| 65 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"> |
| 66 | <td><nobr><b><span class="typelabel">class</span> <tt id='l2h-1863' xml:id='l2h-1863' class="class">timedelta</tt></b>(</nobr></td> |
| 67 | <td><var></var><big>[</big><var>days</var><big>[</big><var>, seconds</var><big>[</big><var>, |
| 68 | microseconds</var><big>[</big><var>, milliseconds</var><big>[</big><var>, |
| 69 | minutes</var><big>[</big><var>, hours</var><big>[</big><var>, weeks</var><big>]</big><var></var><big>]</big><var></var><big>]</big><var></var><big>]</big><var></var><big>]</big><var></var><big>]</big><var></var><big>]</big><var></var>)</td></tr></table></dt> |
| 70 | <dd> |
| 71 | All arguments are optional and default to <code>0</code>. Arguments may |
| 72 | be ints, longs, or floats, and may be positive or negative. |
| 73 | |
| 74 | <P> |
| 75 | Only <var>days</var>, <var>seconds</var> and <var>microseconds</var> are stored |
| 76 | internally. Arguments are converted to those units: |
| 77 | |
| 78 | <P> |
| 79 | |
| 80 | <UL> |
| 81 | <LI>A millisecond is converted to 1000 microseconds. |
| 82 | </LI> |
| 83 | <LI>A minute is converted to 60 seconds. |
| 84 | </LI> |
| 85 | <LI>An hour is converted to 3600 seconds. |
| 86 | </LI> |
| 87 | <LI>A week is converted to 7 days. |
| 88 | </LI> |
| 89 | </UL> |
| 90 | |
| 91 | <P> |
| 92 | and days, seconds and microseconds are then normalized so that the |
| 93 | representation is unique, with |
| 94 | |
| 95 | <P> |
| 96 | |
| 97 | <UL> |
| 98 | <LI><code>0 <= <var>microseconds</var> < 1000000</code> |
| 99 | </LI> |
| 100 | <LI><code>0 <= <var>seconds</var> < 3600*24</code> (the number of seconds in one day) |
| 101 | </LI> |
| 102 | <LI><code>-999999999 <= <var>days</var> <= 999999999</code> |
| 103 | </LI> |
| 104 | </UL> |
| 105 | |
| 106 | <P> |
| 107 | If any argument is a float and there are fractional microseconds, |
| 108 | the fractional microseconds left over from all arguments are combined |
| 109 | and their sum is rounded to the nearest microsecond. If no |
| 110 | argument is a float, the conversion and normalization processes |
| 111 | are exact (no information is lost). |
| 112 | |
| 113 | <P> |
| 114 | If the normalized value of days lies outside the indicated range, |
| 115 | <tt class="exception">OverflowError</tt> is raised. |
| 116 | |
| 117 | <P> |
| 118 | Note that normalization of negative values may be surprising at first. |
| 119 | For example, |
| 120 | |
| 121 | <P> |
| 122 | <div class="verbatim"><pre> |
| 123 | >>> d = timedelta(microseconds=-1) |
| 124 | >>> (d.days, d.seconds, d.microseconds) |
| 125 | (-1, 86399, 999999) |
| 126 | </pre></div> |
| 127 | </dl> |
| 128 | |
| 129 | <P> |
| 130 | Class attributes are: |
| 131 | |
| 132 | <P> |
| 133 | <dl><dt><b><tt id='l2h-1864' xml:id='l2h-1864' class="member">min</tt></b></dt> |
| 134 | <dd> |
| 135 | The most negative <tt class="class">timedelta</tt> object, |
| 136 | <code>timedelta(-999999999)</code>. |
| 137 | </dl> |
| 138 | |
| 139 | <P> |
| 140 | <dl><dt><b><tt id='l2h-1865' xml:id='l2h-1865' class="member">max</tt></b></dt> |
| 141 | <dd> |
| 142 | The most positive <tt class="class">timedelta</tt> object, |
| 143 | <code>timedelta(days=999999999, hours=23, minutes=59, seconds=59, |
| 144 | microseconds=999999)</code>. |
| 145 | </dl> |
| 146 | |
| 147 | <P> |
| 148 | <dl><dt><b><tt id='l2h-1866' xml:id='l2h-1866' class="member">resolution</tt></b></dt> |
| 149 | <dd> |
| 150 | The smallest possible difference between non-equal |
| 151 | <tt class="class">timedelta</tt> objects, <code>timedelta(microseconds=1)</code>. |
| 152 | </dl> |
| 153 | |
| 154 | <P> |
| 155 | Note that, because of normalization, <code>timedelta.max</code> > |
| 156 | <code>-timedelta.min</code>. <code>-timedelta.max</code> is not representable as |
| 157 | a <tt class="class">timedelta</tt> object. |
| 158 | |
| 159 | <P> |
| 160 | Instance attributes (read-only): |
| 161 | |
| 162 | <P> |
| 163 | <div class="center"><table class="realtable"> |
| 164 | <thead> |
| 165 | <tr> |
| 166 | <th class="center">Attribute</th> |
| 167 | <th class="left" >Value</th> |
| 168 | </tr> |
| 169 | </thead> |
| 170 | <tbody> |
| 171 | <tr><td class="center" valign="baseline"><code>days</code></td> |
| 172 | <td class="left" >Between -999999999 and 999999999 inclusive</td></tr> |
| 173 | <tr><td class="center" valign="baseline"><code>seconds</code></td> |
| 174 | <td class="left" >Between 0 and 86399 inclusive</td></tr> |
| 175 | <tr><td class="center" valign="baseline"><code>microseconds</code></td> |
| 176 | <td class="left" >Between 0 and 999999 inclusive</td></tr></tbody> |
| 177 | </table></div> |
| 178 | |
| 179 | <P> |
| 180 | Supported operations: |
| 181 | |
| 182 | <P> |
| 183 | <div class="center"><table class="realtable"> |
| 184 | <thead> |
| 185 | <tr> |
| 186 | <th class="center">Operation</th> |
| 187 | <th class="left" >Result</th> |
| 188 | </tr> |
| 189 | </thead> |
| 190 | <tbody> |
| 191 | <tr><td class="center" valign="baseline"><code><var>t1</var> = <var>t2</var> + <var>t3</var></code></td> |
| 192 | <td class="left" >Sum of <var>t2</var> and <var>t3</var>. |
| 193 | Afterwards <var>t1</var>-<var>t2</var> == <var>t3</var> and <var>t1</var>-<var>t3</var> |
| 194 | == <var>t2</var> are true. |
| 195 | (1)</td></tr> |
| 196 | <tr><td class="center" valign="baseline"><code><var>t1</var> = <var>t2</var> - <var>t3</var></code></td> |
| 197 | <td class="left" >Difference of <var>t2</var> and <var>t3</var>. |
| 198 | Afterwards <var>t1</var> == <var>t2</var> - <var>t3</var> and |
| 199 | <var>t2</var> == <var>t1</var> + <var>t3</var> are true. |
| 200 | (1)</td></tr> |
| 201 | <tr><td class="center" valign="baseline"><code><var>t1</var> = <var>t2</var> * <var>i</var> or <var>t1</var> = <var>i</var> * <var>t2</var></code></td> |
| 202 | <td class="left" >Delta multiplied by an integer or long. |
| 203 | Afterwards <var>t1</var> // i == <var>t2</var> is true, |
| 204 | provided <code>i != 0</code>.</td></tr> |
| 205 | <tr><td class="center" valign="baseline"><code></code></td> |
| 206 | <td class="left" >In general, <var>t1</var> * i == <var>t1</var> * (i-1) + <var>t1</var> is true. |
| 207 | (1)</td></tr> |
| 208 | <tr><td class="center" valign="baseline"><code><var>t1</var> = <var>t2</var> // <var>i</var></code></td> |
| 209 | <td class="left" >The floor is computed and the remainder (if any) is thrown away. |
| 210 | (3)</td></tr> |
| 211 | <tr><td class="center" valign="baseline"><code>+<var>t1</var></code></td> |
| 212 | <td class="left" >Returns a <tt class="class">timedelta</tt> object with the same value. |
| 213 | (2)</td></tr> |
| 214 | <tr><td class="center" valign="baseline"><code>-<var>t1</var></code></td> |
| 215 | <td class="left" >equivalent to <tt class="class">timedelta</tt>(-<var>t1.days</var>, -<var>t1.seconds</var>, |
| 216 | -<var>t1.microseconds</var>), and to <var>t1</var>* -1. |
| 217 | (1)(4)</td></tr> |
| 218 | <tr><td class="center" valign="baseline"><code>abs(<var>t</var>)</code></td> |
| 219 | <td class="left" >equivalent to +<var>t</var> when <code>t.days >= 0</code>, and to |
| 220 | -<var>t</var> when <code>t.days < 0</code>. |
| 221 | (2)</td></tr></tbody> |
| 222 | </table></div> |
| 223 | |
| 224 | Notes: |
| 225 | |
| 226 | <P> |
| 227 | <DL> |
| 228 | <DT><STRONG>(1)</STRONG></DT> |
| 229 | <DD>This is exact, but may overflow. |
| 230 | |
| 231 | <P> |
| 232 | </DD> |
| 233 | <DT><STRONG>(2)</STRONG></DT> |
| 234 | <DD>This is exact, and cannot overflow. |
| 235 | |
| 236 | <P> |
| 237 | </DD> |
| 238 | <DT><STRONG>(3)</STRONG></DT> |
| 239 | <DD>Division by 0 raises <tt class="exception">ZeroDivisionError</tt>. |
| 240 | |
| 241 | <P> |
| 242 | </DD> |
| 243 | <DT><STRONG>(4)</STRONG></DT> |
| 244 | <DD>-<var>timedelta.max</var> is not representable as a <tt class="class">timedelta</tt> object. |
| 245 | </DD> |
| 246 | </DL> |
| 247 | |
| 248 | <P> |
| 249 | In addition to the operations listed above <tt class="class">timedelta</tt> objects |
| 250 | support certain additions and subtractions with <tt class="class">date</tt> and |
| 251 | <tt class="class">datetime</tt> objects (see below). |
| 252 | |
| 253 | <P> |
| 254 | Comparisons of <tt class="class">timedelta</tt> objects are supported with the |
| 255 | <tt class="class">timedelta</tt> object representing the smaller duration considered |
| 256 | to be the smaller timedelta. |
| 257 | In order to stop mixed-type comparisons from falling back to the |
| 258 | default comparison by object address, when a <tt class="class">timedelta</tt> object is |
| 259 | compared to an object of a different type, <tt class="exception">TypeError</tt> is |
| 260 | raised unless the comparison is <code>==</code> or <code>!=</code>. The latter |
| 261 | cases return <tt class="constant">False</tt> or <tt class="constant">True</tt>, respectively. |
| 262 | |
| 263 | <P> |
| 264 | <tt class="class">timedelta</tt> objects are hashable (usable as dictionary keys), |
| 265 | support efficient pickling, and in Boolean contexts, a <tt class="class">timedelta</tt> |
| 266 | object is considered to be true if and only if it isn't equal to |
| 267 | <code>timedelta(0)</code>. |
| 268 | |
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