libs/geometry/doc/html/geometry/reference/algorithms/clear.html

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  26 <div class="titlepage"><div><div><h4 class="title">
  27 <a name="geometry.reference.algorithms.clear"></a><a class="link" href="clear.html" title="clear">clear</a>
  28 </h4></div></div></div>
  29 <p>
  30           <a class="indexterm" name="idm46187006797552"></a>
  31 Clears a linestring, ring or polygon (exterior+interiors) or multi*.
  32         </p>
  33 <h6>
  34 <a name="geometry.reference.algorithms.clear.h0"></a>
  35           <span class="phrase"><a name="geometry.reference.algorithms.clear.description"></a></span><a class="link" href="clear.html#geometry.reference.algorithms.clear.description">Description</a>
  36         </h6>
  37 <p>
  38           Generic function to clear a geometry. All points will be removed from the
  39           collection or collections making up the geometry. In most cases this is
  40           equivalent to the .clear() method of a std::vector&lt;...&gt;. In the case
  41           of a polygon, this clear functionality is automatically called for the
  42           exterior ring, and for the interior ring collection. In the case of a point,
  43           boxes and segments, nothing will happen.
  44         </p>
  45 <h6>
  46 <a name="geometry.reference.algorithms.clear.h1"></a>
  47           <span class="phrase"><a name="geometry.reference.algorithms.clear.synopsis"></a></span><a class="link" href="clear.html#geometry.reference.algorithms.clear.synopsis">Synopsis</a>
  48         </h6>
  49 <p>
  50 </p>
  51 <pre class="programlisting"><span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Geometry</span><span class="special">&gt;</span>
  52 <span class="keyword">void</span> <span class="identifier">clear</span><span class="special">(</span><span class="identifier">Geometry</span> <span class="special">&amp;</span> <span class="identifier">geometry</span><span class="special">)</span></pre>
  53 <p>
  54         </p>
  55 <h6>
  56 <a name="geometry.reference.algorithms.clear.h2"></a>
  57           <span class="phrase"><a name="geometry.reference.algorithms.clear.parameters"></a></span><a class="link" href="clear.html#geometry.reference.algorithms.clear.parameters">Parameters</a>
  58         </h6>
  59 <div class="informaltable"><table class="table">
  60 <colgroup>
  61 <col>
  62 <col>
  63 <col>
  64 <col>
  65 </colgroup>
  66 <thead><tr>
  67 <th>
  68                   <p>
  69                     Type
  70                   </p>
  71                 </th>
  72 <th>
  73                   <p>
  74                     Concept
  75                   </p>
  76                 </th>
  77 <th>
  78                   <p>
  79                     Name
  80                   </p>
  81                 </th>
  82 <th>
  83                   <p>
  84                     Description
  85                   </p>
  86                 </th>
  87 </tr></thead>
  88 <tbody><tr>
  89 <td>
  90                   <p>
  91                     Geometry &amp;
  92                   </p>
  93                 </td>
  94 <td>
  95                   <p>
  96                     Any type fulfilling a Geometry Concept
  97                   </p>
  98                 </td>
  99 <td>
 100                   <p>
 101                     geometry
 102                   </p>
 103                 </td>
 104 <td>
 105                   <p>
 106                     A model of the specified concept which will be cleared
 107                   </p>
 108                 </td>
 109 </tr></tbody>
 110 </table></div>
 111 <h6>
 112 <a name="geometry.reference.algorithms.clear.h3"></a>
 113           <span class="phrase"><a name="geometry.reference.algorithms.clear.header"></a></span><a class="link" href="clear.html#geometry.reference.algorithms.clear.header">Header</a>
 114         </h6>
 115 <p>
 116           Either
 117         </p>
 118 <p>
 119           <code class="computeroutput"><span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">geometry</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span></code>
 120         </p>
 121 <p>
 122           Or
 123         </p>
 124 <p>
 125           <code class="computeroutput"><span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">geometry</span><span class="special">/</span><span class="identifier">algorithms</span><span class="special">/</span><span class="identifier">clear</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span></code>
 126         </p>
 127 <h6>
 128 <a name="geometry.reference.algorithms.clear.h4"></a>
 129           <span class="phrase"><a name="geometry.reference.algorithms.clear.conformance"></a></span><a class="link" href="clear.html#geometry.reference.algorithms.clear.conformance">Conformance</a>
 130         </h6>
 131 <p>
 132           The function clear is not defined by OGC.
 133         </p>
 134 <p>
 135           The function clear conforms to the clear() method of the C++ std-library.
 136         </p>
 137 <h6>
 138 <a name="geometry.reference.algorithms.clear.h5"></a>
 139           <span class="phrase"><a name="geometry.reference.algorithms.clear.supported_geometries"></a></span><a class="link" href="clear.html#geometry.reference.algorithms.clear.supported_geometries">Supported
 140           geometries</a>
 141         </h6>
 142 <div class="informaltable"><table class="table">
 143 <colgroup>
 144 <col>
 145 <col>
 146 </colgroup>
 147 <thead><tr>
 148 <th>
 149                   <p>
 150                     Geometry
 151                   </p>
 152                 </th>
 153 <th>
 154                   <p>
 155                     Status
 156                   </p>
 157                 </th>
 158 </tr></thead>
 159 <tbody>
 160 <tr>
 161 <td>
 162                   <p>
 163                     Point
 164                   </p>
 165                 </td>
 166 <td>
 167                   <p>
 168                     <span class="inlinemediaobject"><img src="../../../img/ok.png" alt="ok"></span>
 169                   </p>
 170                 </td>
 171 </tr>
 172 <tr>
 173 <td>
 174                   <p>
 175                     Segment
 176                   </p>
 177                 </td>
 178 <td>
 179                   <p>
 180                     <span class="inlinemediaobject"><img src="../../../img/ok.png" alt="ok"></span>
 181                   </p>
 182                 </td>
 183 </tr>
 184 <tr>
 185 <td>
 186                   <p>
 187                     Box
 188                   </p>
 189                 </td>
 190 <td>
 191                   <p>
 192                     <span class="inlinemediaobject"><img src="../../../img/ok.png" alt="ok"></span>
 193                   </p>
 194                 </td>
 195 </tr>
 196 <tr>
 197 <td>
 198                   <p>
 199                     Linestring
 200                   </p>
 201                 </td>
 202 <td>
 203                   <p>
 204                     <span class="inlinemediaobject"><img src="../../../img/ok.png" alt="ok"></span>
 205                   </p>
 206                 </td>
 207 </tr>
 208 <tr>
 209 <td>
 210                   <p>
 211                     Ring
 212                   </p>
 213                 </td>
 214 <td>
 215                   <p>
 216                     <span class="inlinemediaobject"><img src="../../../img/ok.png" alt="ok"></span>
 217                   </p>
 218                 </td>
 219 </tr>
 220 <tr>
 221 <td>
 222                   <p>
 223                     Polygon
 224                   </p>
 225                 </td>
 226 <td>
 227                   <p>
 228                     <span class="inlinemediaobject"><img src="../../../img/ok.png" alt="ok"></span>
 229                   </p>
 230                 </td>
 231 </tr>
 232 <tr>
 233 <td>
 234                   <p>
 235                     MultiPoint
 236                   </p>
 237                 </td>
 238 <td>
 239                   <p>
 240                     <span class="inlinemediaobject"><img src="../../../img/ok.png" alt="ok"></span>
 241                   </p>
 242                 </td>
 243 </tr>
 244 <tr>
 245 <td>
 246                   <p>
 247                     MultiLinestring
 248                   </p>
 249                 </td>
 250 <td>
 251                   <p>
 252                     <span class="inlinemediaobject"><img src="../../../img/ok.png" alt="ok"></span>
 253                   </p>
 254                 </td>
 255 </tr>
 256 <tr>
 257 <td>
 258                   <p>
 259                     MultiPolygon
 260                   </p>
 261                 </td>
 262 <td>
 263                   <p>
 264                     <span class="inlinemediaobject"><img src="../../../img/ok.png" alt="ok"></span>
 265                   </p>
 266                 </td>
 267 </tr>
 268 <tr>
 269 <td>
 270                   <p>
 271                     Variant
 272                   </p>
 273                 </td>
 274 <td>
 275                   <p>
 276                     <span class="inlinemediaobject"><img src="../../../img/ok.png" alt="ok"></span>
 277                   </p>
 278                 </td>
 279 </tr>
 280 </tbody>
 281 </table></div>
 282 <h6>
 283 <a name="geometry.reference.algorithms.clear.h6"></a>
 284           <span class="phrase"><a name="geometry.reference.algorithms.clear.behavior"></a></span><a class="link" href="clear.html#geometry.reference.algorithms.clear.behavior">Behavior</a>
 285         </h6>
 286 <div class="informaltable"><table class="table">
 287 <colgroup>
 288 <col>
 289 <col>
 290 </colgroup>
 291 <thead><tr>
 292 <th>
 293                   <p>
 294                     Case
 295                   </p>
 296                 </th>
 297 <th>
 298                   <p>
 299                     Behavior
 300                   </p>
 301                 </th>
 302 </tr></thead>
 303 <tbody>
 304 <tr>
 305 <td>
 306                   <p>
 307                     Point
 308                   </p>
 309                 </td>
 310 <td>
 311                   <p>
 312                     Nothing happens, geometry is unchanged
 313                   </p>
 314                 </td>
 315 </tr>
 316 <tr>
 317 <td>
 318                   <p>
 319                     Segment
 320                   </p>
 321                 </td>
 322 <td>
 323                   <p>
 324                     Nothing happens, geometry is unchanged
 325                   </p>
 326                 </td>
 327 </tr>
 328 <tr>
 329 <td>
 330                   <p>
 331                     Box
 332                   </p>
 333                 </td>
 334 <td>
 335                   <p>
 336                     Nothing happens, geometry is unchanged
 337                   </p>
 338                 </td>
 339 </tr>
 340 <tr>
 341 <td>
 342                   <p>
 343                     Linestring
 344                   </p>
 345                 </td>
 346 <td>
 347                   <p>
 348                     Linestring is cleared
 349                   </p>
 350                 </td>
 351 </tr>
 352 <tr>
 353 <td>
 354                   <p>
 355                     Ring
 356                   </p>
 357                 </td>
 358 <td>
 359                   <p>
 360                     Ring is cleared
 361                   </p>
 362                 </td>
 363 </tr>
 364 <tr>
 365 <td>
 366                   <p>
 367                     Polygon
 368                   </p>
 369                 </td>
 370 <td>
 371                   <p>
 372                     The exterior ring is cleared and all interior rings are removed
 373                   </p>
 374                 </td>
 375 </tr>
 376 <tr>
 377 <td>
 378                   <p>
 379                     Multi Point
 380                   </p>
 381                 </td>
 382 <td>
 383                   <p>
 384                     Multi Point is cleared
 385                   </p>
 386                 </td>
 387 </tr>
 388 <tr>
 389 <td>
 390                   <p>
 391                     Multi Linestring
 392                   </p>
 393                 </td>
 394 <td>
 395                   <p>
 396                     Multi Linestring is cleared
 397                   </p>
 398                 </td>
 399 </tr>
 400 <tr>
 401 <td>
 402                   <p>
 403                     Multi Polygon
 404                   </p>
 405                 </td>
 406 <td>
 407                   <p>
 408                     Multi Polygon is cleared
 409                   </p>
 410                 </td>
 411 </tr>
 412 </tbody>
 413 </table></div>
 414 <h6>
 415 <a name="geometry.reference.algorithms.clear.h7"></a>
 416           <span class="phrase"><a name="geometry.reference.algorithms.clear.complexity"></a></span><a class="link" href="clear.html#geometry.reference.algorithms.clear.complexity">Complexity</a>
 417         </h6>
 418 <p>
 419           Constant
 420         </p>
 421 <h6>
 422 <a name="geometry.reference.algorithms.clear.h8"></a>
 423           <span class="phrase"><a name="geometry.reference.algorithms.clear.example"></a></span><a class="link" href="clear.html#geometry.reference.algorithms.clear.example">Example</a>
 424         </h6>
 425 <p>
 426           Shows how to clear a ring or polygon
 427         </p>
 428 <p>
 429 </p>
 430 <pre class="programlisting"><span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">iostream</span><span class="special">&gt;</span>
 431
 432 <span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">geometry</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>
 433 <span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">geometry</span><span class="special">/</span><span class="identifier">geometries</span><span class="special">/</span><span class="identifier">polygon</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>
 434 <span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">geometry</span><span class="special">/</span><span class="identifier">geometries</span><span class="special">/</span><span class="identifier">ring</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>
 435 <span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">geometry</span><span class="special">/</span><span class="identifier">geometries</span><span class="special">/</span><span class="identifier">adapted</span><span class="special">/</span><span class="identifier">boost_tuple</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>
 436
 437 <span class="identifier">BOOST_GEOMETRY_REGISTER_BOOST_TUPLE_CS</span><span class="special">(</span><span class="identifier">cs</span><span class="special">::</span><span class="identifier">cartesian</span><span class="special">)</span>
 438
 439 <span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">assign</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>
 440
 441 <span class="keyword">int</span> <span class="identifier">main</span><span class="special">()</span>
 442 <span class="special">{</span>
 443     <span class="keyword">using</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">assign</span><span class="special">::</span><span class="identifier">tuple_list_of</span><span class="special">;</span>
 444
 445     <span class="keyword">typedef</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">tuple</span><span class="special">&lt;</span><span class="keyword">float</span><span class="special">,</span> <span class="keyword">float</span><span class="special">&gt;</span> <span class="identifier">point</span><span class="special">;</span>
 446     <span class="keyword">typedef</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">geometry</span><span class="special">::</span><span class="identifier">model</span><span class="special">::</span><span class="identifier">polygon</span><span class="special">&lt;</span><span class="identifier">point</span><span class="special">&gt;</span> <span class="identifier">polygon</span><span class="special">;</span>
 447     <span class="keyword">typedef</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">geometry</span><span class="special">::</span><span class="identifier">model</span><span class="special">::</span><span class="identifier">ring</span><span class="special">&lt;</span><span class="identifier">point</span><span class="special">&gt;</span> <span class="identifier">ring</span><span class="special">;</span>
 448
 449     <span class="identifier">polygon</span> <span class="identifier">poly</span><span class="special">;</span>
 450
 451     <span class="comment">// Fill the polygon (using its own methods + Boost.Assign)</span>
 452     <span class="identifier">poly</span><span class="special">.</span><span class="identifier">outer</span><span class="special">()</span> <span class="special">=</span> <span class="identifier">tuple_list_of</span><span class="special">(</span><span class="number">0</span><span class="special">,</span> <span class="number">0</span><span class="special">)(</span><span class="number">0</span><span class="special">,</span> <span class="number">9</span><span class="special">)(</span><span class="number">10</span><span class="special">,</span> <span class="number">10</span><span class="special">)(</span><span class="number">0</span><span class="special">,</span> <span class="number">0</span><span class="special">);</span>
 453     <span class="identifier">poly</span><span class="special">.</span><span class="identifier">inners</span><span class="special">().</span><span class="identifier">push_back</span><span class="special">(</span><span class="identifier">tuple_list_of</span><span class="special">(</span><span class="number">1</span><span class="special">,</span> <span class="number">2</span><span class="special">)(</span><span class="number">4</span><span class="special">,</span> <span class="number">6</span><span class="special">)(</span><span class="number">2</span><span class="special">,</span> <span class="number">8</span><span class="special">)(</span><span class="number">1</span><span class="special">,</span> <span class="number">2</span><span class="special">));</span>
 454
 455     <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special">&lt;&lt;</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">geometry</span><span class="special">::</span><span class="identifier">dsv</span><span class="special">(</span><span class="identifier">poly</span><span class="special">)</span> <span class="special">&lt;&lt;</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span>
 456     <span class="identifier">boost</span><span class="special">::</span><span class="identifier">geometry</span><span class="special">::</span><span class="identifier">clear</span><span class="special">(</span><span class="identifier">poly</span><span class="special">);</span>
 457     <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special">&lt;&lt;</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">geometry</span><span class="special">::</span><span class="identifier">dsv</span><span class="special">(</span><span class="identifier">poly</span><span class="special">)</span> <span class="special">&lt;&lt;</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span>
 458
 459     <span class="comment">// Create a ring using Boost.Assign</span>
 460     <span class="identifier">ring</span> <span class="identifier">r</span> <span class="special">=</span> <span class="identifier">tuple_list_of</span><span class="special">(</span><span class="number">0</span><span class="special">,</span> <span class="number">0</span><span class="special">)(</span><span class="number">0</span><span class="special">,</span> <span class="number">9</span><span class="special">)(</span><span class="number">8</span><span class="special">,</span> <span class="number">8</span><span class="special">)(</span><span class="number">0</span><span class="special">,</span> <span class="number">0</span><span class="special">);</span>
 461
 462     <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special">&lt;&lt;</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">geometry</span><span class="special">::</span><span class="identifier">dsv</span><span class="special">(</span><span class="identifier">r</span><span class="special">)</span> <span class="special">&lt;&lt;</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span>
 463     <span class="identifier">boost</span><span class="special">::</span><span class="identifier">geometry</span><span class="special">::</span><span class="identifier">clear</span><span class="special">(</span><span class="identifier">r</span><span class="special">);</span>
 464     <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special">&lt;&lt;</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">geometry</span><span class="special">::</span><span class="identifier">dsv</span><span class="special">(</span><span class="identifier">r</span><span class="special">)</span> <span class="special">&lt;&lt;</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span>
 465
 466     <span class="keyword">return</span> <span class="number">0</span><span class="special">;</span>
 467 <span class="special">}</span>
 468 </pre>
 469 <p>
 470         </p>
 471 <p>
 472           Output:
 473         </p>
 474 <pre class="programlisting">(((0, 0), (0, 10), (11, 11), (0, 0)), ((0, 0), (0, 10), (11, 11), (0, 0)))
 475 (())
 476 ((0, 0), (0, 9), (8, 8), (0, 0))
 477 ()
 478 </pre>
 479 </div>
 480 <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
 481 <td align="left"></td>
 482 <td align="right"><div class="copyright-footer">Copyright &#169; 2009-2019 Barend Gehrels, Bruno Lalande, Mateusz Loskot, Adam
 483       Wulkiewicz, Oracle and/or its affiliates<p>
 484         Distributed under the Boost Software License, Version 1.0. (See accompanying
 485         file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)
 486       </p>
 487 </div></td>
 488 </tr></table>
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