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<li class="navelem"><a class="el" href="namespacedatasketches.html">datasketches</a></li><li class="navelem"><a class="el" href="classdatasketches_1_1frequent__items__sketch.html">frequent_items_sketch</a></li> </ul>
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<div class="header">
<div class="summary">
<a href="#nested-classes">Classes</a> &#124;
<a href="#pub-methods">Public Member Functions</a> &#124;
<a href="#pub-static-methods">Static Public Member Functions</a> &#124;
<a href="classdatasketches_1_1frequent__items__sketch-members.html">List of all members</a> </div>
<div class="headertitle"><div class="title">frequent_items_sketch&lt; T, W, H, E, A &gt; Class Template Reference</div></div>
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<p>Frequent Items sketch.
<a href="classdatasketches_1_1frequent__items__sketch.html#details">More...</a></p>
<p><code>#include &lt;<a class="el" href="frequent__items__sketch_8hpp_source.html">frequent_items_sketch.hpp</a>&gt;</code></p>
<table class="memberdecls">
<tr class="heading"><td colspan="2"><h2 class="groupheader"><a id="nested-classes" name="nested-classes"></a>
Classes</h2></td></tr>
<tr class="memitem:"><td class="memItemLeft" align="right" valign="top">class &#160;</td><td class="memItemRight" valign="bottom"><a class="el" href="classdatasketches_1_1frequent__items__sketch_1_1row.html">row</a></td></tr>
<tr class="memdesc:"><td class="mdescLeft">&#160;</td><td class="mdescRight">Row in the output from <a class="el" href="classdatasketches_1_1frequent__items__sketch.html#a5412230c8878e0cc1be2c6940512f508" title="Returns an array of rows that include frequent items, estimates, upper and lower bounds given an erro...">get_frequent_items</a>. <a href="classdatasketches_1_1frequent__items__sketch_1_1row.html#details">More...</a><br /></td></tr>
<tr class="separator:"><td class="memSeparator" colspan="2">&#160;</td></tr>
</table><table class="memberdecls">
<tr class="heading"><td colspan="2"><h2 class="groupheader"><a id="pub-methods" name="pub-methods"></a>
Public Member Functions</h2></td></tr>
<tr class="memitem:a225f700985a82a592a6fd7dc685d6044" id="r_a225f700985a82a592a6fd7dc685d6044"><td class="memItemLeft" align="right" valign="top">&#160;</td><td class="memItemRight" valign="bottom"><a class="el" href="classdatasketches_1_1frequent__items__sketch.html#a225f700985a82a592a6fd7dc685d6044">frequent_items_sketch</a> (uint8_t lg_max_map_size, uint8_t lg_start_map_size=LG_MIN_MAP_SIZE, const E &amp;equal=E(), const A &amp;allocator=A())</td></tr>
<tr class="memdesc:a225f700985a82a592a6fd7dc685d6044"><td class="mdescLeft">&#160;</td><td class="mdescRight">Construct this sketch with parameters lg_max_map_size and lg_start_map_size. <br /></td></tr>
<tr class="separator:a225f700985a82a592a6fd7dc685d6044"><td class="memSeparator" colspan="2">&#160;</td></tr>
<tr class="memitem:a61957693a9a6d2b20882579d40e4f775" id="r_a61957693a9a6d2b20882579d40e4f775"><td class="memItemLeft" align="right" valign="top">void&#160;</td><td class="memItemRight" valign="bottom"><a class="el" href="classdatasketches_1_1frequent__items__sketch.html#a61957693a9a6d2b20882579d40e4f775">update</a> (const T &amp;item, W weight=1)</td></tr>
<tr class="memdesc:a61957693a9a6d2b20882579d40e4f775"><td class="mdescLeft">&#160;</td><td class="mdescRight">Update this sketch with an item and a positive weight (frequency count). <br /></td></tr>
<tr class="separator:a61957693a9a6d2b20882579d40e4f775"><td class="memSeparator" colspan="2">&#160;</td></tr>
<tr class="memitem:a1217d7712089fac3876c35b210ac4c5e" id="r_a1217d7712089fac3876c35b210ac4c5e"><td class="memItemLeft" align="right" valign="top">void&#160;</td><td class="memItemRight" valign="bottom"><a class="el" href="classdatasketches_1_1frequent__items__sketch.html#a1217d7712089fac3876c35b210ac4c5e">update</a> (T &amp;&amp;item, W weight=1)</td></tr>
<tr class="memdesc:a1217d7712089fac3876c35b210ac4c5e"><td class="mdescLeft">&#160;</td><td class="mdescRight">Update this sketch with an item and a positive weight (frequency count). <br /></td></tr>
<tr class="separator:a1217d7712089fac3876c35b210ac4c5e"><td class="memSeparator" colspan="2">&#160;</td></tr>
<tr class="memitem:a3384eaa5ad927a987343cdc509bd4f9c" id="r_a3384eaa5ad927a987343cdc509bd4f9c"><td class="memItemLeft" align="right" valign="top">void&#160;</td><td class="memItemRight" valign="bottom"><a class="el" href="classdatasketches_1_1frequent__items__sketch.html#a3384eaa5ad927a987343cdc509bd4f9c">merge</a> (const <a class="el" href="classdatasketches_1_1frequent__items__sketch.html">frequent_items_sketch</a> &amp;other)</td></tr>
<tr class="memdesc:a3384eaa5ad927a987343cdc509bd4f9c"><td class="mdescLeft">&#160;</td><td class="mdescRight">This function merges the other sketch into this one. <br /></td></tr>
<tr class="separator:a3384eaa5ad927a987343cdc509bd4f9c"><td class="memSeparator" colspan="2">&#160;</td></tr>
<tr class="memitem:a67646860b1cb8e835604a008fd7d062a" id="r_a67646860b1cb8e835604a008fd7d062a"><td class="memItemLeft" align="right" valign="top">void&#160;</td><td class="memItemRight" valign="bottom"><a class="el" href="classdatasketches_1_1frequent__items__sketch.html#a67646860b1cb8e835604a008fd7d062a">merge</a> (<a class="el" href="classdatasketches_1_1frequent__items__sketch.html">frequent_items_sketch</a> &amp;&amp;other)</td></tr>
<tr class="memdesc:a67646860b1cb8e835604a008fd7d062a"><td class="mdescLeft">&#160;</td><td class="mdescRight">This function merges the other sketch into this one. <br /></td></tr>
<tr class="separator:a67646860b1cb8e835604a008fd7d062a"><td class="memSeparator" colspan="2">&#160;</td></tr>
<tr class="memitem:a5a2b7a58dc85678d08752945ff655362" id="r_a5a2b7a58dc85678d08752945ff655362"><td class="memItemLeft" align="right" valign="top">bool&#160;</td><td class="memItemRight" valign="bottom"><a class="el" href="classdatasketches_1_1frequent__items__sketch.html#a5a2b7a58dc85678d08752945ff655362">is_empty</a> () const</td></tr>
<tr class="separator:a5a2b7a58dc85678d08752945ff655362"><td class="memSeparator" colspan="2">&#160;</td></tr>
<tr class="memitem:af72439eee5521a156379f0fbd869cb12" id="r_af72439eee5521a156379f0fbd869cb12"><td class="memItemLeft" align="right" valign="top">uint32_t&#160;</td><td class="memItemRight" valign="bottom"><a class="el" href="classdatasketches_1_1frequent__items__sketch.html#af72439eee5521a156379f0fbd869cb12">get_num_active_items</a> () const</td></tr>
<tr class="separator:af72439eee5521a156379f0fbd869cb12"><td class="memSeparator" colspan="2">&#160;</td></tr>
<tr class="memitem:a68bf5133e42650cdfe20a7916037ab4b" id="r_a68bf5133e42650cdfe20a7916037ab4b"><td class="memItemLeft" align="right" valign="top">W&#160;</td><td class="memItemRight" valign="bottom"><a class="el" href="classdatasketches_1_1frequent__items__sketch.html#a68bf5133e42650cdfe20a7916037ab4b">get_total_weight</a> () const</td></tr>
<tr class="memdesc:a68bf5133e42650cdfe20a7916037ab4b"><td class="mdescLeft">&#160;</td><td class="mdescRight">Returns the sum of the weights (frequencies) in the stream seen so far by the sketch. <br /></td></tr>
<tr class="separator:a68bf5133e42650cdfe20a7916037ab4b"><td class="memSeparator" colspan="2">&#160;</td></tr>
<tr class="memitem:ab1b012eb1b049bf5a4fd0f02916655a3" id="r_ab1b012eb1b049bf5a4fd0f02916655a3"><td class="memItemLeft" align="right" valign="top">W&#160;</td><td class="memItemRight" valign="bottom"><a class="el" href="classdatasketches_1_1frequent__items__sketch.html#ab1b012eb1b049bf5a4fd0f02916655a3">get_estimate</a> (const T &amp;item) const</td></tr>
<tr class="memdesc:ab1b012eb1b049bf5a4fd0f02916655a3"><td class="mdescLeft">&#160;</td><td class="mdescRight">Returns the estimate of the weight (frequency) of the given item. <br /></td></tr>
<tr class="separator:ab1b012eb1b049bf5a4fd0f02916655a3"><td class="memSeparator" colspan="2">&#160;</td></tr>
<tr class="memitem:aed55e478ed35c861c3351b90c88fdbe7" id="r_aed55e478ed35c861c3351b90c88fdbe7"><td class="memItemLeft" align="right" valign="top">W&#160;</td><td class="memItemRight" valign="bottom"><a class="el" href="classdatasketches_1_1frequent__items__sketch.html#aed55e478ed35c861c3351b90c88fdbe7">get_lower_bound</a> (const T &amp;item) const</td></tr>
<tr class="memdesc:aed55e478ed35c861c3351b90c88fdbe7"><td class="mdescLeft">&#160;</td><td class="mdescRight">Returns the guaranteed lower bound weight (frequency) of the given item. <br /></td></tr>
<tr class="separator:aed55e478ed35c861c3351b90c88fdbe7"><td class="memSeparator" colspan="2">&#160;</td></tr>
<tr class="memitem:a2489b27ac0658fc4151aa98f0fb638f7" id="r_a2489b27ac0658fc4151aa98f0fb638f7"><td class="memItemLeft" align="right" valign="top">W&#160;</td><td class="memItemRight" valign="bottom"><a class="el" href="classdatasketches_1_1frequent__items__sketch.html#a2489b27ac0658fc4151aa98f0fb638f7">get_upper_bound</a> (const T &amp;item) const</td></tr>
<tr class="memdesc:a2489b27ac0658fc4151aa98f0fb638f7"><td class="mdescLeft">&#160;</td><td class="mdescRight">Returns the guaranteed upper bound weight (frequency) of the given item. <br /></td></tr>
<tr class="separator:a2489b27ac0658fc4151aa98f0fb638f7"><td class="memSeparator" colspan="2">&#160;</td></tr>
<tr class="memitem:aa6a8295801139cde1c0136867cf1f188" id="r_aa6a8295801139cde1c0136867cf1f188"><td class="memItemLeft" align="right" valign="top">W&#160;</td><td class="memItemRight" valign="bottom"><a class="el" href="classdatasketches_1_1frequent__items__sketch.html#aa6a8295801139cde1c0136867cf1f188">get_maximum_error</a> () const</td></tr>
<tr class="separator:aa6a8295801139cde1c0136867cf1f188"><td class="memSeparator" colspan="2">&#160;</td></tr>
<tr class="memitem:a7d758ee3fb67c30c547628bd8cc2d266" id="r_a7d758ee3fb67c30c547628bd8cc2d266"><td class="memItemLeft" align="right" valign="top">double&#160;</td><td class="memItemRight" valign="bottom"><a class="el" href="classdatasketches_1_1frequent__items__sketch.html#a7d758ee3fb67c30c547628bd8cc2d266">get_epsilon</a> () const</td></tr>
<tr class="memdesc:a7d758ee3fb67c30c547628bd8cc2d266"><td class="mdescLeft">&#160;</td><td class="mdescRight">Returns epsilon value of this sketch. <br /></td></tr>
<tr class="separator:a7d758ee3fb67c30c547628bd8cc2d266"><td class="memSeparator" colspan="2">&#160;</td></tr>
<tr class="memitem:a5412230c8878e0cc1be2c6940512f508" id="r_a5412230c8878e0cc1be2c6940512f508"><td class="memItemLeft" align="right" valign="top">vector_row&#160;</td><td class="memItemRight" valign="bottom"><a class="el" href="classdatasketches_1_1frequent__items__sketch.html#a5412230c8878e0cc1be2c6940512f508">get_frequent_items</a> (<a class="el" href="namespacedatasketches.html#ae94a02fc822bc3f745ab6ef0ac9c1f0f">frequent_items_error_type</a> err_type) const</td></tr>
<tr class="memdesc:a5412230c8878e0cc1be2c6940512f508"><td class="mdescLeft">&#160;</td><td class="mdescRight">Returns an array of rows that include frequent items, estimates, upper and lower bounds given an error_type and using <a class="el" href="classdatasketches_1_1frequent__items__sketch.html#aa6a8295801139cde1c0136867cf1f188">get_maximum_error()</a> as a threshold. <br /></td></tr>
<tr class="separator:a5412230c8878e0cc1be2c6940512f508"><td class="memSeparator" colspan="2">&#160;</td></tr>
<tr class="memitem:a9b0618f5181938adc5bd00b9f40516b9" id="r_a9b0618f5181938adc5bd00b9f40516b9"><td class="memItemLeft" align="right" valign="top">vector_row&#160;</td><td class="memItemRight" valign="bottom"><a class="el" href="classdatasketches_1_1frequent__items__sketch.html#a9b0618f5181938adc5bd00b9f40516b9">get_frequent_items</a> (<a class="el" href="namespacedatasketches.html#ae94a02fc822bc3f745ab6ef0ac9c1f0f">frequent_items_error_type</a> err_type, W threshold) const</td></tr>
<tr class="memdesc:a9b0618f5181938adc5bd00b9f40516b9"><td class="mdescLeft">&#160;</td><td class="mdescRight">Returns an array of rows that include frequent items, estimates, upper and lower bounds given an error_type and a threshold. <br /></td></tr>
<tr class="separator:a9b0618f5181938adc5bd00b9f40516b9"><td class="memSeparator" colspan="2">&#160;</td></tr>
<tr class="memitem:a8762fed25b3024f07989976344dd0afb" id="r_a8762fed25b3024f07989976344dd0afb"><td class="memTemplParams" colspan="2">template&lt;typename SerDe = serde&lt;T&gt;&gt; </td></tr>
<tr class="memitem:a8762fed25b3024f07989976344dd0afb"><td class="memTemplItemLeft" align="right" valign="top">size_t&#160;</td><td class="memTemplItemRight" valign="bottom"><a class="el" href="classdatasketches_1_1frequent__items__sketch.html#a8762fed25b3024f07989976344dd0afb">get_serialized_size_bytes</a> (const SerDe &amp;sd=SerDe()) const</td></tr>
<tr class="memdesc:a8762fed25b3024f07989976344dd0afb"><td class="mdescLeft">&#160;</td><td class="mdescRight">Computes size needed to serialize the current state of the sketch. <br /></td></tr>
<tr class="separator:a8762fed25b3024f07989976344dd0afb"><td class="memSeparator" colspan="2">&#160;</td></tr>
<tr class="memitem:a538940c100e4353b3671ad452d3d3056" id="r_a538940c100e4353b3671ad452d3d3056"><td class="memTemplParams" colspan="2">template&lt;typename SerDe = serde&lt;T&gt;&gt; </td></tr>
<tr class="memitem:a538940c100e4353b3671ad452d3d3056"><td class="memTemplItemLeft" align="right" valign="top">void&#160;</td><td class="memTemplItemRight" valign="bottom"><a class="el" href="classdatasketches_1_1frequent__items__sketch.html#a538940c100e4353b3671ad452d3d3056">serialize</a> (std::ostream &amp;os, const SerDe &amp;sd=SerDe()) const</td></tr>
<tr class="memdesc:a538940c100e4353b3671ad452d3d3056"><td class="mdescLeft">&#160;</td><td class="mdescRight">This method serializes the sketch into a given stream in a binary form. <br /></td></tr>
<tr class="separator:a538940c100e4353b3671ad452d3d3056"><td class="memSeparator" colspan="2">&#160;</td></tr>
<tr class="memitem:a1d0c269c23926e93b1c7a9c00e86af97" id="r_a1d0c269c23926e93b1c7a9c00e86af97"><td class="memTemplParams" colspan="2">template&lt;typename SerDe = serde&lt;T&gt;&gt; </td></tr>
<tr class="memitem:a1d0c269c23926e93b1c7a9c00e86af97"><td class="memTemplItemLeft" align="right" valign="top">vector_bytes&#160;</td><td class="memTemplItemRight" valign="bottom"><a class="el" href="classdatasketches_1_1frequent__items__sketch.html#a1d0c269c23926e93b1c7a9c00e86af97">serialize</a> (unsigned header_size_bytes=0, const SerDe &amp;sd=SerDe()) const</td></tr>
<tr class="memdesc:a1d0c269c23926e93b1c7a9c00e86af97"><td class="mdescLeft">&#160;</td><td class="mdescRight">This method serializes the sketch as a vector of bytes. <br /></td></tr>
<tr class="separator:a1d0c269c23926e93b1c7a9c00e86af97"><td class="memSeparator" colspan="2">&#160;</td></tr>
<tr class="memitem:a60a5fe73c86554c313705666f8fb227a" id="r_a60a5fe73c86554c313705666f8fb227a"><td class="memItemLeft" align="right" valign="top">string&lt; A &gt;&#160;</td><td class="memItemRight" valign="bottom"><a class="el" href="classdatasketches_1_1frequent__items__sketch.html#a60a5fe73c86554c313705666f8fb227a">to_string</a> (bool print_items=false) const</td></tr>
<tr class="memdesc:a60a5fe73c86554c313705666f8fb227a"><td class="mdescLeft">&#160;</td><td class="mdescRight">Returns a human readable summary of this sketch. <br /></td></tr>
<tr class="separator:a60a5fe73c86554c313705666f8fb227a"><td class="memSeparator" colspan="2">&#160;</td></tr>
</table><table class="memberdecls">
<tr class="heading"><td colspan="2"><h2 class="groupheader"><a id="pub-static-methods" name="pub-static-methods"></a>
Static Public Member Functions</h2></td></tr>
<tr class="memitem:a88b29ea8d3966b76de96e183789f7f3e" id="r_a88b29ea8d3966b76de96e183789f7f3e"><td class="memItemLeft" align="right" valign="top">static double&#160;</td><td class="memItemRight" valign="bottom"><a class="el" href="classdatasketches_1_1frequent__items__sketch.html#a88b29ea8d3966b76de96e183789f7f3e">get_epsilon</a> (uint8_t lg_max_map_size)</td></tr>
<tr class="memdesc:a88b29ea8d3966b76de96e183789f7f3e"><td class="mdescLeft">&#160;</td><td class="mdescRight">Returns epsilon used to compute <em>a priori</em> error. <br /></td></tr>
<tr class="separator:a88b29ea8d3966b76de96e183789f7f3e"><td class="memSeparator" colspan="2">&#160;</td></tr>
<tr class="memitem:a6731cfa90aabc42089e1f449d3aa9a66" id="r_a6731cfa90aabc42089e1f449d3aa9a66"><td class="memItemLeft" align="right" valign="top">static double&#160;</td><td class="memItemRight" valign="bottom"><a class="el" href="classdatasketches_1_1frequent__items__sketch.html#a6731cfa90aabc42089e1f449d3aa9a66">get_apriori_error</a> (uint8_t lg_max_map_size, W estimated_total_weight)</td></tr>
<tr class="memdesc:a6731cfa90aabc42089e1f449d3aa9a66"><td class="mdescLeft">&#160;</td><td class="mdescRight">Returns the estimated <em>a priori</em> error given the max_map_size for the sketch and the estimated_total_stream_weight. <br /></td></tr>
<tr class="separator:a6731cfa90aabc42089e1f449d3aa9a66"><td class="memSeparator" colspan="2">&#160;</td></tr>
<tr class="memitem:aba8b57f65dd3f4d47be9aacbb3606118" id="r_aba8b57f65dd3f4d47be9aacbb3606118"><td class="memTemplParams" colspan="2">template&lt;typename SerDe = serde&lt;T&gt;&gt; </td></tr>
<tr class="memitem:aba8b57f65dd3f4d47be9aacbb3606118"><td class="memTemplItemLeft" align="right" valign="top">static <a class="el" href="classdatasketches_1_1frequent__items__sketch.html">frequent_items_sketch</a>&#160;</td><td class="memTemplItemRight" valign="bottom"><a class="el" href="classdatasketches_1_1frequent__items__sketch.html#aba8b57f65dd3f4d47be9aacbb3606118">deserialize</a> (std::istream &amp;is, const SerDe &amp;sd=SerDe(), const E &amp;equal=E(), const A &amp;allocator=A())</td></tr>
<tr class="memdesc:aba8b57f65dd3f4d47be9aacbb3606118"><td class="mdescLeft">&#160;</td><td class="mdescRight">This method deserializes a sketch from a given stream. <br /></td></tr>
<tr class="separator:aba8b57f65dd3f4d47be9aacbb3606118"><td class="memSeparator" colspan="2">&#160;</td></tr>
<tr class="memitem:a732aa172ee6b88b39ba3dfb79ca646f8" id="r_a732aa172ee6b88b39ba3dfb79ca646f8"><td class="memTemplParams" colspan="2">template&lt;typename SerDe = serde&lt;T&gt;&gt; </td></tr>
<tr class="memitem:a732aa172ee6b88b39ba3dfb79ca646f8"><td class="memTemplItemLeft" align="right" valign="top">static <a class="el" href="classdatasketches_1_1frequent__items__sketch.html">frequent_items_sketch</a>&#160;</td><td class="memTemplItemRight" valign="bottom"><a class="el" href="classdatasketches_1_1frequent__items__sketch.html#a732aa172ee6b88b39ba3dfb79ca646f8">deserialize</a> (const void *bytes, size_t size, const SerDe &amp;sd=SerDe(), const E &amp;equal=E(), const A &amp;allocator=A())</td></tr>
<tr class="memdesc:a732aa172ee6b88b39ba3dfb79ca646f8"><td class="mdescLeft">&#160;</td><td class="mdescRight">This method deserializes a sketch from a given array of bytes. <br /></td></tr>
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<a name="details" id="details"></a><h2 class="groupheader">Detailed Description</h2>
<div class="textblock"><div class="compoundTemplParams">template&lt;typename T, typename W = uint64_t, typename H = std::hash&lt;T&gt;, typename E = std::equal_to&lt;T&gt;, typename A = std::allocator&lt;T&gt;&gt;<br />
class datasketches::frequent_items_sketch&lt; T, W, H, E, A &gt;</div><p>Frequent Items sketch. </p>
<p>Based on Java implementation here: <a href="https://github.com/apache/datasketches-java/blob/master/src/main/java/org/apache/datasketches/frequencies/ItemsSketch.java">https://github.com/apache/datasketches-java/blob/master/src/main/java/org/apache/datasketches/frequencies/ItemsSketch.java</a> </p><dl class="section author"><dt>Author</dt><dd>Alexander Saydakov </dd></dl>
</div><h2 class="groupheader">Constructor &amp; Destructor Documentation</h2>
<a id="a225f700985a82a592a6fd7dc685d6044" name="a225f700985a82a592a6fd7dc685d6044"></a>
<h2 class="memtitle"><span class="permalink"><a href="#a225f700985a82a592a6fd7dc685d6044">&#9670;&#160;</a></span>frequent_items_sketch()</h2>
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<td class="memname"><a class="el" href="classdatasketches_1_1frequent__items__sketch.html">frequent_items_sketch</a> </td>
<td>(</td>
<td class="paramtype">uint8_t&#160;</td>
<td class="paramname"><em>lg_max_map_size</em>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype">uint8_t&#160;</td>
<td class="paramname"><em>lg_start_map_size</em> = <code>LG_MIN_MAP_SIZE</code>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype">const E &amp;&#160;</td>
<td class="paramname"><em>equal</em> = <code>E()</code>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype">const A &amp;&#160;</td>
<td class="paramname"><em>allocator</em> = <code>A()</code>&#160;</td>
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<tr>
<td></td>
<td>)</td>
<td></td><td></td>
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<span class="mlabels"><span class="mlabel">explicit</span></span> </td>
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<p>Construct this sketch with parameters lg_max_map_size and lg_start_map_size. </p>
<dl class="params"><dt>Parameters</dt><dd>
<table class="params">
<tr><td class="paramname">lg_max_map_size</td><td>Log2 of the physical size of the internal hash map managed by this sketch. The maximum capacity of this internal hash map is 0.75 times 2^lg_max_map_size. Both the ultimate accuracy and size of this sketch are functions of lg_max_map_size. </td></tr>
<tr><td class="paramname">lg_start_map_size</td><td>Log2 of the starting physical size of the internal hash map managed by this sketch. </td></tr>
<tr><td class="paramname">equal</td><td>instance of Equality operator </td></tr>
<tr><td class="paramname">allocator</td><td>instance of an Allocator </td></tr>
</table>
</dd>
</dl>
</div>
</div>
<h2 class="groupheader">Member Function Documentation</h2>
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<h2 class="memtitle"><span class="permalink"><a href="#a61957693a9a6d2b20882579d40e4f775">&#9670;&#160;</a></span>update() <span class="overload">[1/2]</span></h2>
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<td class="memname">void update </td>
<td>(</td>
<td class="paramtype">const T &amp;&#160;</td>
<td class="paramname"><em>item</em>, </td>
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<td class="paramkey"></td>
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<td class="paramname"><em>weight</em> = <code>1</code>&#160;</td>
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<td>)</td>
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<p>Update this sketch with an item and a positive weight (frequency count). </p>
<dl class="params"><dt>Parameters</dt><dd>
<table class="params">
<tr><td class="paramname">item</td><td>for which the weight should be increased (lvalue) </td></tr>
<tr><td class="paramname">weight</td><td>the amount by which the weight of the item should be increased A count of zero is a no-op, and a negative count will throw an exception. </td></tr>
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</dd>
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<h2 class="memtitle"><span class="permalink"><a href="#a1217d7712089fac3876c35b210ac4c5e">&#9670;&#160;</a></span>update() <span class="overload">[2/2]</span></h2>
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<td class="memname">void update </td>
<td>(</td>
<td class="paramtype">T &amp;&amp;&#160;</td>
<td class="paramname"><em>item</em>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype">W&#160;</td>
<td class="paramname"><em>weight</em> = <code>1</code>&#160;</td>
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<td>)</td>
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<p>Update this sketch with an item and a positive weight (frequency count). </p>
<dl class="params"><dt>Parameters</dt><dd>
<table class="params">
<tr><td class="paramname">item</td><td>for which the weight should be increased (rvalue) </td></tr>
<tr><td class="paramname">weight</td><td>the amount by which the weight of the item should be increased A count of zero is a no-op, and a negative count will throw an exception. </td></tr>
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</dd>
</dl>
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<h2 class="memtitle"><span class="permalink"><a href="#a3384eaa5ad927a987343cdc509bd4f9c">&#9670;&#160;</a></span>merge() <span class="overload">[1/2]</span></h2>
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<td class="paramtype">const <a class="el" href="classdatasketches_1_1frequent__items__sketch.html">frequent_items_sketch</a>&lt; T, W, H, E, A &gt; &amp;&#160;</td>
<td class="paramname"><em>other</em></td><td>)</td>
<td></td>
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<p>This function merges the other sketch into this one. </p>
<p>The other sketch may be of a different size. </p><dl class="params"><dt>Parameters</dt><dd>
<table class="params">
<tr><td class="paramname">other</td><td>sketch to be merged into this (lvalue) </td></tr>
</table>
</dd>
</dl>
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<h2 class="memtitle"><span class="permalink"><a href="#a67646860b1cb8e835604a008fd7d062a">&#9670;&#160;</a></span>merge() <span class="overload">[2/2]</span></h2>
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<td class="paramtype"><a class="el" href="classdatasketches_1_1frequent__items__sketch.html">frequent_items_sketch</a>&lt; T, W, H, E, A &gt; &amp;&amp;&#160;</td>
<td class="paramname"><em>other</em></td><td>)</td>
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<p>This function merges the other sketch into this one. </p>
<p>The other sketch may be of a different size. </p><dl class="params"><dt>Parameters</dt><dd>
<table class="params">
<tr><td class="paramname">other</td><td>sketch to be merged into this (rvalue) </td></tr>
</table>
</dd>
</dl>
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<h2 class="memtitle"><span class="permalink"><a href="#a5a2b7a58dc85678d08752945ff655362">&#9670;&#160;</a></span>is_empty()</h2>
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<dl class="section return"><dt>Returns</dt><dd>true if this sketch is empty </dd></dl>
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<h2 class="memtitle"><span class="permalink"><a href="#af72439eee5521a156379f0fbd869cb12">&#9670;&#160;</a></span>get_num_active_items()</h2>
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<dl class="section return"><dt>Returns</dt><dd>the number of active items in the sketch </dd></dl>
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<h2 class="memtitle"><span class="permalink"><a href="#a68bf5133e42650cdfe20a7916037ab4b">&#9670;&#160;</a></span>get_total_weight()</h2>
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<td class="memname">W get_total_weight </td>
<td>(</td>
<td class="paramname"></td><td>)</td>
<td> const</td>
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<p>Returns the sum of the weights (frequencies) in the stream seen so far by the sketch. </p>
<dl class="section return"><dt>Returns</dt><dd>the total weight of all items in the stream seen so far by the sketch </dd></dl>
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<h2 class="memtitle"><span class="permalink"><a href="#ab1b012eb1b049bf5a4fd0f02916655a3">&#9670;&#160;</a></span>get_estimate()</h2>
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<td class="memname">W get_estimate </td>
<td>(</td>
<td class="paramtype">const T &amp;&#160;</td>
<td class="paramname"><em>item</em></td><td>)</td>
<td> const</td>
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<p>Returns the estimate of the weight (frequency) of the given item. </p>
<p>Note: The true frequency of a item would be the sum of the counts as a result of the two update functions.</p>
<dl class="params"><dt>Parameters</dt><dd>
<table class="params">
<tr><td class="paramname">item</td><td>the given item </td></tr>
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</dd>
</dl>
<dl class="section return"><dt>Returns</dt><dd>the estimate of the weight (frequency) of the given item </dd></dl>
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<h2 class="memtitle"><span class="permalink"><a href="#aed55e478ed35c861c3351b90c88fdbe7">&#9670;&#160;</a></span>get_lower_bound()</h2>
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<td class="paramtype">const T &amp;&#160;</td>
<td class="paramname"><em>item</em></td><td>)</td>
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<p>Returns the guaranteed lower bound weight (frequency) of the given item. </p>
<dl class="params"><dt>Parameters</dt><dd>
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<tr><td class="paramname">item</td><td>the given item. </td></tr>
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<dl class="section return"><dt>Returns</dt><dd>the guaranteed lower bound weight of the given item. That is, a number which is guaranteed to be no larger than the real weight. </dd></dl>
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<h2 class="memtitle"><span class="permalink"><a href="#a2489b27ac0658fc4151aa98f0fb638f7">&#9670;&#160;</a></span>get_upper_bound()</h2>
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<td class="memname">W get_upper_bound </td>
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<p>Returns the guaranteed upper bound weight (frequency) of the given item. </p>
<dl class="params"><dt>Parameters</dt><dd>
<table class="params">
<tr><td class="paramname">item</td><td>the given item </td></tr>
</table>
</dd>
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<dl class="section return"><dt>Returns</dt><dd>the guaranteed upper bound weight of the given item. That is, a number which is guaranteed to be no smaller than the real frequency. </dd></dl>
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<h2 class="memtitle"><span class="permalink"><a href="#aa6a8295801139cde1c0136867cf1f188">&#9670;&#160;</a></span>get_maximum_error()</h2>
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<dl class="section return"><dt>Returns</dt><dd>An upper bound on the maximum error of get_estimate(item) for any item. This is equivalent to the maximum distance between the upper bound and the lower bound for any item. </dd></dl>
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<h2 class="memtitle"><span class="permalink"><a href="#a7d758ee3fb67c30c547628bd8cc2d266">&#9670;&#160;</a></span>get_epsilon() <span class="overload">[1/2]</span></h2>
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<p>Returns epsilon value of this sketch. </p>
<p>This is just the value <em>3.5 / max_map_size</em>. </p><dl class="section return"><dt>Returns</dt><dd>epsilon used by the sketch to compute error. </dd></dl>
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<h2 class="memtitle"><span class="permalink"><a href="#a88b29ea8d3966b76de96e183789f7f3e">&#9670;&#160;</a></span>get_epsilon() <span class="overload">[2/2]</span></h2>
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<td>(</td>
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<td class="paramname"><em>lg_max_map_size</em></td><td>)</td>
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<p>Returns epsilon used to compute <em>a priori</em> error. </p>
<p>This is just the value <em>3.5 / maxMapSize</em>. </p><dl class="params"><dt>Parameters</dt><dd>
<table class="params">
<tr><td class="paramname">lg_max_map_size</td><td>the planned map size to be used when constructing this sketch. </td></tr>
</table>
</dd>
</dl>
<dl class="section return"><dt>Returns</dt><dd>epsilon used to compute <em>a priori</em> error. </dd></dl>
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<h2 class="memtitle"><span class="permalink"><a href="#a6731cfa90aabc42089e1f449d3aa9a66">&#9670;&#160;</a></span>get_apriori_error()</h2>
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<td class="memname">double get_apriori_error </td>
<td>(</td>
<td class="paramtype">uint8_t&#160;</td>
<td class="paramname"><em>lg_max_map_size</em>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype">W&#160;</td>
<td class="paramname"><em>estimated_total_weight</em>&#160;</td>
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<tr>
<td></td>
<td>)</td>
<td></td><td></td>
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<p>Returns the estimated <em>a priori</em> error given the max_map_size for the sketch and the estimated_total_stream_weight. </p>
<dl class="params"><dt>Parameters</dt><dd>
<table class="params">
<tr><td class="paramname">lg_max_map_size</td><td>the planned map size to be used when constructing this sketch. </td></tr>
<tr><td class="paramname">estimated_total_weight</td><td>the estimated total stream weight. </td></tr>
</table>
</dd>
</dl>
<dl class="section return"><dt>Returns</dt><dd>the estimated <em>a priori</em> error. </dd></dl>
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<h2 class="memtitle"><span class="permalink"><a href="#a5412230c8878e0cc1be2c6940512f508">&#9670;&#160;</a></span>get_frequent_items() <span class="overload">[1/2]</span></h2>
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template&lt;typename T , typename W , typename H , typename E , typename A &gt; </div>
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<td class="memname">auto get_frequent_items </td>
<td>(</td>
<td class="paramtype"><a class="el" href="namespacedatasketches.html#ae94a02fc822bc3f745ab6ef0ac9c1f0f">frequent_items_error_type</a>&#160;</td>
<td class="paramname"><em>err_type</em></td><td>)</td>
<td> const</td>
</tr>
</table>
</div><div class="memdoc">
<p>Returns an array of rows that include frequent items, estimates, upper and lower bounds given an error_type and using <a class="el" href="classdatasketches_1_1frequent__items__sketch.html#aa6a8295801139cde1c0136867cf1f188">get_maximum_error()</a> as a threshold. </p>
<p>The method first examines all active items in the sketch (items that have a counter).</p>
<p>If <em>error_type = NO_FALSE_NEGATIVES</em>, this will include an item in the result list if get_upper_bound(item) &gt; threshold. There will be no false negatives, i.e., no Type II error. There may be items in the set with true frequencies less than the threshold (false positives).</p>
<p>If <em>error_type = NO_FALSE_POSITIVES</em>, this will include an item in the result list if get_lower_bound(item) &gt; threshold. There will be no false positives, i.e., no Type I error. There may be items omitted from the set with true frequencies greater than the threshold (false negatives).</p>
<dl class="params"><dt>Parameters</dt><dd>
<table class="params">
<tr><td class="paramname">err_type</td><td>determines whether no false positives or no false negatives are desired. </td></tr>
</table>
</dd>
</dl>
<dl class="section return"><dt>Returns</dt><dd>an array of frequent items </dd></dl>
</div>
</div>
<a id="a9b0618f5181938adc5bd00b9f40516b9" name="a9b0618f5181938adc5bd00b9f40516b9"></a>
<h2 class="memtitle"><span class="permalink"><a href="#a9b0618f5181938adc5bd00b9f40516b9">&#9670;&#160;</a></span>get_frequent_items() <span class="overload">[2/2]</span></h2>
<div class="memitem">
<div class="memproto">
<div class="memtemplate">
template&lt;typename T , typename W , typename H , typename E , typename A &gt; </div>
<table class="memname">
<tr>
<td class="memname">auto get_frequent_items </td>
<td>(</td>
<td class="paramtype"><a class="el" href="namespacedatasketches.html#ae94a02fc822bc3f745ab6ef0ac9c1f0f">frequent_items_error_type</a>&#160;</td>
<td class="paramname"><em>err_type</em>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype">W&#160;</td>
<td class="paramname"><em>threshold</em>&#160;</td>
</tr>
<tr>
<td></td>
<td>)</td>
<td></td><td> const</td>
</tr>
</table>
</div><div class="memdoc">
<p>Returns an array of rows that include frequent items, estimates, upper and lower bounds given an error_type and a threshold. </p>
<p>The method first examines all active items in the sketch (items that have a counter).</p>
<p>If <em>error_type = NO_FALSE_NEGATIVES</em>, this will include an item in the result list if get_upper_bound(item) &gt; threshold. There will be no false negatives, i.e., no Type II error. There may be items in the set with true frequencies less than the threshold (false positives).</p>
<p>If <em>error_type = NO_FALSE_POSITIVES</em>, this will include an item in the result list if get_lower_bound(item) &gt; threshold. There will be no false positives, i.e., no Type I error. There may be items omitted from the set with true frequencies greater than the threshold (false negatives).</p>
<dl class="params"><dt>Parameters</dt><dd>
<table class="params">
<tr><td class="paramname">err_type</td><td>determines whether no false positives or no false negatives are desired. </td></tr>
<tr><td class="paramname">threshold</td><td>to include items in the result list </td></tr>
</table>
</dd>
</dl>
<dl class="section return"><dt>Returns</dt><dd>an array of frequent items </dd></dl>
</div>
</div>
<a id="a8762fed25b3024f07989976344dd0afb" name="a8762fed25b3024f07989976344dd0afb"></a>
<h2 class="memtitle"><span class="permalink"><a href="#a8762fed25b3024f07989976344dd0afb">&#9670;&#160;</a></span>get_serialized_size_bytes()</h2>
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<div class="memproto">
<div class="memtemplate">
template&lt;typename T , typename W , typename H , typename E , typename A &gt; </div>
<div class="memtemplate">
template&lt;typename SerDe &gt; </div>
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<td class="memname">size_t get_serialized_size_bytes </td>
<td>(</td>
<td class="paramtype">const SerDe &amp;&#160;</td>
<td class="paramname"><em>sd</em> = <code>SerDe()</code></td><td>)</td>
<td> const</td>
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<p>Computes size needed to serialize the current state of the sketch. </p>
<p>This can be expensive since every item needs to be looked at. </p><dl class="params"><dt>Parameters</dt><dd>
<table class="params">
<tr><td class="paramname">sd</td><td>instance of a SerDe </td></tr>
</table>
</dd>
</dl>
<dl class="section return"><dt>Returns</dt><dd>size in bytes needed to serialize this sketch </dd></dl>
</div>
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<a id="a538940c100e4353b3671ad452d3d3056" name="a538940c100e4353b3671ad452d3d3056"></a>
<h2 class="memtitle"><span class="permalink"><a href="#a538940c100e4353b3671ad452d3d3056">&#9670;&#160;</a></span>serialize() <span class="overload">[1/2]</span></h2>
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template&lt;typename T , typename W , typename H , typename E , typename A &gt; </div>
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template&lt;typename SerDe &gt; </div>
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<td class="memname">void serialize </td>
<td>(</td>
<td class="paramtype">std::ostream &amp;&#160;</td>
<td class="paramname"><em>os</em>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype">const SerDe &amp;&#160;</td>
<td class="paramname"><em>sd</em> = <code>SerDe()</code>&#160;</td>
</tr>
<tr>
<td></td>
<td>)</td>
<td></td><td> const</td>
</tr>
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<p>This method serializes the sketch into a given stream in a binary form. </p>
<dl class="params"><dt>Parameters</dt><dd>
<table class="params">
<tr><td class="paramname">os</td><td>output stream </td></tr>
<tr><td class="paramname">sd</td><td>instance of a SerDe </td></tr>
</table>
</dd>
</dl>
</div>
</div>
<a id="a1d0c269c23926e93b1c7a9c00e86af97" name="a1d0c269c23926e93b1c7a9c00e86af97"></a>
<h2 class="memtitle"><span class="permalink"><a href="#a1d0c269c23926e93b1c7a9c00e86af97">&#9670;&#160;</a></span>serialize() <span class="overload">[2/2]</span></h2>
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template&lt;typename T , typename W = uint64_t, typename H = std::hash&lt;T&gt;, typename E = std::equal_to&lt;T&gt;, typename A = std::allocator&lt;T&gt;&gt; </div>
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template&lt;typename SerDe = serde&lt;T&gt;&gt; </div>
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<td class="memname">vector_bytes serialize </td>
<td>(</td>
<td class="paramtype">unsigned&#160;</td>
<td class="paramname"><em>header_size_bytes</em> = <code>0</code>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype">const SerDe &amp;&#160;</td>
<td class="paramname"><em>sd</em> = <code>SerDe()</code>&#160;</td>
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<tr>
<td></td>
<td>)</td>
<td></td><td> const</td>
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<p>This method serializes the sketch as a vector of bytes. </p>
<p>An optional header can be reserved in front of the sketch. It is a blank space of a given size. This header is used in Datasketches PostgreSQL extension. </p><dl class="params"><dt>Parameters</dt><dd>
<table class="params">
<tr><td class="paramname">header_size_bytes</td><td>space to reserve in front of the sketch </td></tr>
<tr><td class="paramname">sd</td><td>instance of a SerDe </td></tr>
</table>
</dd>
</dl>
<dl class="section return"><dt>Returns</dt><dd>serialized sketch as a vector of bytes </dd></dl>
</div>
</div>
<a id="aba8b57f65dd3f4d47be9aacbb3606118" name="aba8b57f65dd3f4d47be9aacbb3606118"></a>
<h2 class="memtitle"><span class="permalink"><a href="#aba8b57f65dd3f4d47be9aacbb3606118">&#9670;&#160;</a></span>deserialize() <span class="overload">[1/2]</span></h2>
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<div class="memproto">
<div class="memtemplate">
template&lt;typename T , typename W = uint64_t, typename H = std::hash&lt;T&gt;, typename E = std::equal_to&lt;T&gt;, typename A = std::allocator&lt;T&gt;&gt; </div>
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template&lt;typename SerDe = serde&lt;T&gt;&gt; </div>
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<td class="memname">static <a class="el" href="classdatasketches_1_1frequent__items__sketch.html">frequent_items_sketch</a> deserialize </td>
<td>(</td>
<td class="paramtype">std::istream &amp;&#160;</td>
<td class="paramname"><em>is</em>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype">const SerDe &amp;&#160;</td>
<td class="paramname"><em>sd</em> = <code>SerDe()</code>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype">const E &amp;&#160;</td>
<td class="paramname"><em>equal</em> = <code>E()</code>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype">const A &amp;&#160;</td>
<td class="paramname"><em>allocator</em> = <code>A()</code>&#160;</td>
</tr>
<tr>
<td></td>
<td>)</td>
<td></td><td></td>
</tr>
</table>
</td>
<td class="mlabels-right">
<span class="mlabels"><span class="mlabel">static</span></span> </td>
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</div><div class="memdoc">
<p>This method deserializes a sketch from a given stream. </p>
<dl class="params"><dt>Parameters</dt><dd>
<table class="params">
<tr><td class="paramname">is</td><td>input stream </td></tr>
<tr><td class="paramname">sd</td><td>instance of a SerDe </td></tr>
<tr><td class="paramname">equal</td><td>instance of Equality operator </td></tr>
<tr><td class="paramname">allocator</td><td>instance of an Allocator </td></tr>
</table>
</dd>
</dl>
<dl class="section return"><dt>Returns</dt><dd>an instance of the sketch </dd></dl>
</div>
</div>
<a id="a732aa172ee6b88b39ba3dfb79ca646f8" name="a732aa172ee6b88b39ba3dfb79ca646f8"></a>
<h2 class="memtitle"><span class="permalink"><a href="#a732aa172ee6b88b39ba3dfb79ca646f8">&#9670;&#160;</a></span>deserialize() <span class="overload">[2/2]</span></h2>
<div class="memitem">
<div class="memproto">
<div class="memtemplate">
template&lt;typename T , typename W = uint64_t, typename H = std::hash&lt;T&gt;, typename E = std::equal_to&lt;T&gt;, typename A = std::allocator&lt;T&gt;&gt; </div>
<div class="memtemplate">
template&lt;typename SerDe = serde&lt;T&gt;&gt; </div>
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<td class="mlabels-left">
<table class="memname">
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<td class="memname">static <a class="el" href="classdatasketches_1_1frequent__items__sketch.html">frequent_items_sketch</a> deserialize </td>
<td>(</td>
<td class="paramtype">const void *&#160;</td>
<td class="paramname"><em>bytes</em>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype">size_t&#160;</td>
<td class="paramname"><em>size</em>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype">const SerDe &amp;&#160;</td>
<td class="paramname"><em>sd</em> = <code>SerDe()</code>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype">const E &amp;&#160;</td>
<td class="paramname"><em>equal</em> = <code>E()</code>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype">const A &amp;&#160;</td>
<td class="paramname"><em>allocator</em> = <code>A()</code>&#160;</td>
</tr>
<tr>
<td></td>
<td>)</td>
<td></td><td></td>
</tr>
</table>
</td>
<td class="mlabels-right">
<span class="mlabels"><span class="mlabel">static</span></span> </td>
</tr>
</table>
</div><div class="memdoc">
<p>This method deserializes a sketch from a given array of bytes. </p>
<dl class="params"><dt>Parameters</dt><dd>
<table class="params">
<tr><td class="paramname">bytes</td><td>pointer to the array of bytes </td></tr>
<tr><td class="paramname">size</td><td>the size of the array </td></tr>
<tr><td class="paramname">sd</td><td>instance of a SerDe </td></tr>
<tr><td class="paramname">equal</td><td>instance of Equality operator </td></tr>
<tr><td class="paramname">allocator</td><td>instance of an Allocator </td></tr>
</table>
</dd>
</dl>
<dl class="section return"><dt>Returns</dt><dd>an instance of the sketch </dd></dl>
</div>
</div>
<a id="a60a5fe73c86554c313705666f8fb227a" name="a60a5fe73c86554c313705666f8fb227a"></a>
<h2 class="memtitle"><span class="permalink"><a href="#a60a5fe73c86554c313705666f8fb227a">&#9670;&#160;</a></span>to_string()</h2>
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<div class="memtemplate">
template&lt;typename T , typename W , typename H , typename E , typename A &gt; </div>
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<td class="memname">string&lt; A &gt; to_string </td>
<td>(</td>
<td class="paramtype">bool&#160;</td>
<td class="paramname"><em>print_items</em> = <code>false</code></td><td>)</td>
<td> const</td>
</tr>
</table>
</div><div class="memdoc">
<p>Returns a human readable summary of this sketch. </p>
<dl class="params"><dt>Parameters</dt><dd>
<table class="params">
<tr><td class="paramname">print_items</td><td>if true include the list of items retained by the sketch </td></tr>
</table>
</dd>
</dl>
</div>
</div>
<hr/>The documentation for this class was generated from the following files:<ul>
<li>fi/include/<a class="el" href="frequent__items__sketch_8hpp_source.html">frequent_items_sketch.hpp</a></li>
<li>fi/include/<a class="el" href="frequent__items__sketch__impl_8hpp_source.html">frequent_items_sketch_impl.hpp</a></li>
</ul>
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