<main><divclass="width-limiter"><navclass="sub"><formclass="search-form"><span></span><divid="sidebar-button"tabindex="-1"><ahref="../../itertools/all.html"title="show sidebar"></a></div><inputclass="search-input"name="search"aria-label="Run search in the documentation"autocomplete="off"spellcheck="false"placeholder="Click or press ‘S’ to search, ‘?’ for more options…"type="search"><divid="help-button"tabindex="-1"><ahref="../../help.html"title="help">?</a></div><divid="settings-menu"tabindex="-1"><ahref="../../settings.html"title="settings"><imgwidth="22"height="22"alt="Change settings"src="../../static.files/wheel-7b819b6101059cd0.svg"></a></div></form></nav><sectionid="main-content"class="content"><divclass="main-heading"><h1>Struct <ahref="../index.html">itertools</a>::<wbr><ahref="index.html">structs</a>::<wbr><aclass="struct"href="#">GroupBy</a><buttonid="copy-path"title="Copy item path to clipboard"><imgsrc="../../static.files/clipboard-7571035ce49a181d.svg"width="19"height="18"alt="Copy item path"></button></h1><spanclass="out-of-band"><aclass="src"href="../../src/itertools/groupbylazy.rs.html#299-307">source</a> · <buttonid="toggle-all-docs"title="collapse all docs">[<span>−</span>]</button></span></div><preclass="rust item-decl"><code>pub struct GroupBy<K, I, F><divclass="where">where
I: <aclass="trait"href="https://doc.rust-lang.org/1.78.0/core/iter/traits/iterator/trait.Iterator.html"title="trait core::iter::traits::iterator::Iterator">Iterator</a>,</div>{ <spanclass="comment">/* private fields */</span> }</code></pre><detailsclass="toggle top-doc"open><summaryclass="hideme"><span>Expand description</span></summary><divclass="docblock"><p><code>GroupBy</code> is the storage for the lazy grouping operation.</p>
<p>This type implements <ahref="https://doc.rust-lang.org/1.78.0/core/iter/traits/collect/trait.IntoIterator.html"title="trait core::iter::traits::collect::IntoIterator"><code>IntoIterator</code></a> (it is <strong>not</strong> an iterator
itself), because the group iterators need to borrow from this
value. It should be stored in a local variable or temporary and
iterated.</p>
<p>See <ahref="../trait.Itertools.html#method.group_by"title="method itertools::Itertools::group_by"><code>.group_by()</code></a> for more information.</p>
</div></details><h2id="trait-implementations"class="section-header">Trait Implementations<ahref="#trait-implementations"class="anchor">§</a></h2><divid="trait-implementations-list"><detailsclass="toggle implementors-toggle"open><summary><sectionid="impl-IntoIterator-for-%26GroupBy%3CK,+I,+F%3E"class="impl"><aclass="src rightside"href="../../src/itertools/groupbylazy.rs.html#351-364">source</a><ahref="#impl-IntoIterator-for-%26GroupBy%3CK,+I,+F%3E"class="anchor">§</a><h3class="code-header">impl<'a, K, I, F><aclass="trait"href="https://doc.rust-lang.org/1.78.0/core/iter/traits/collect/trait.IntoIterator.html"title="trait core::iter::traits::collect::IntoIterator">IntoIterator</a> for &'a <aclass="struct"href="struct.GroupBy.html"title="struct itertools::structs::GroupBy">GroupBy</a><K, I, F><divclass="where">where
K: <aclass="trait"href="https://doc.rust-lang.org/1.78.0/core/cmp/trait.PartialEq.html"title="trait core::cmp::PartialEq">PartialEq</a>,</div></h3></section></summary><divclass="impl-items"><detailsclass="toggle"open><summary><sectionid="associatedtype.Item"class="associatedtype trait-impl"><ahref="#associatedtype.Item"class="anchor">§</a><h4class="code-header">type <ahref="https://doc.rust-lang.org/1.78.0/core/iter/traits/collect/trait.IntoIterator.html#associatedtype.Item"class="associatedtype">Item</a> = (K, <aclass="struct"href="struct.Group.html"title="struct itertools::structs::Group">Group</a><'a, K, I, F>)</h4></section></summary><divclass='docblock'>The type of the elements being iterated over.</div></details><detailsclass="toggle"open><summary><sectionid="associatedtype.IntoIter"class="associatedtype trait-impl"><ahref="#associatedtype.IntoIter"class="anchor">§</a><h4class="code-header">type <ahref="https://doc.rust-lang.org/1.78.0/core/iter/traits/collect/trait.IntoIterator.html#associatedtype.IntoIter"class="associatedtype">IntoIter</a> = <aclass="struct"href="struct.Groups.html"title="struct itertools::structs::Groups">Groups</a><'a, K, I, F></h4></section></summary><divclass='docblock'>Which kind of iterator are we turning this into?</div></details><detailsclass="toggle method-toggle"open><summary><sectionid="method.into_iter"class="method trait-impl"><aclass="src rightside"href="../../src/itertools/groupbylazy.rs.html#361-363">source</a><ahref="#method.into_iter"class="anchor">§</a><h4class="code-header">fn <ahref="https://doc.rust-lang.org/1.78.0/core/iter/traits/collect/trait.IntoIterator.html#tymethod.into_iter"class="fn">into_iter</a>(self) -> Self::<aclass="associatedtype"href="https://doc.rust-lang.org/1.78.0/core/iter/traits/collect/trait.IntoIterator.html#associatedtype.IntoIter"title="type core::iter::traits::collect::IntoIterator::IntoIter">IntoIter</a></h4></section></summary><divclass='docblock'>Creates an iterator from a value. <ahref="https://doc.rust-lang.org/1.78.0/core/iter/traits/collect/trait.IntoIterator.html#tymethod.into_iter">Read more</a></div></details></div></details></div><h2id="synthetic-implementations"class="section-header">Auto Trait Implementations<ahref="#synthetic-implementations"class="anchor">§</a></h2><divid="synthetic-implementations-list"><sectionid="impl-Freeze-for-GroupBy%3CK,+I,+F%3E"class="impl"><ahref="#impl-Freeze-for-GroupBy%3CK,+I,+F%3E"class="anchor">§</a><h3class="code-header">impl<K, I, F> !<aclass="trait"href="https://doc.rust-lang.org/1.78.0/core/marker/trait.Freeze.html"title="trait core::marker::Freeze">Freeze</a> for <aclass="struct"href="struct.GroupBy.html"title="struct itertools::structs::GroupBy">GroupBy</a><K, I, F></h3></section><sectionid="impl-RefUnwindSafe-for-GroupBy%3CK,+I,+F%3E"class="impl"><ahref="#impl-RefUnwindSafe-for-GroupBy%3CK,+I,+F%3E"class="anchor">§</a><h3class="code-header">impl<K, I, F> !<aclass="trait"href="https://doc.rust-lang.org/1.78.0/core/panic/unwind_safe/trait.RefUnwindSafe.html"title="trait core::panic::unwind_safe::RefUnwindSafe">RefUnwindSafe</a> for <aclass="struct"href="struct.GroupBy.html"title="struct itertools::structs::GroupBy">GroupBy</a><K, I, F></h3></section><sectionid="impl-Send-for-GroupBy%3CK,+I,+F%3E"class="impl"><ahref="#impl-Send-for-GroupBy%3CK,+I,+F%3E"class="anchor">§</a><h3class="code-header">impl<K, I, F><aclass="trait"href="https://doc.rust-lang.org/1.78.0/core/marker/trait.Send.html"title="trait core::marker::Send">Send</a> for <aclass="struct"href="struct.GroupBy.html"title="struct itertools::structs::GroupBy">GroupBy</a><K, I, F><divclass="where">where
<I as <aclass="trait"href="https://doc.rust-lang.org/1.78.0/core/iter/traits/iterator/trait.Iterator.html"title="trait core::iter::traits::iterator::Iterator">Iterator</a>>::<aclass="associatedtype"href="https://doc.rust-lang.org/1.78.0/core/iter/traits/iterator/trait.Iterator.html#associatedtype.Item"title="type core::iter::traits::iterator::Iterator::Item">Item</a>: <aclass="trait"href="https://doc.rust-lang.org/1.78.0/core/marker/trait.Send.html"title="trait core::marker::Send">Send</a>,</div></h3></section><sectionid="impl-Sync-for-GroupBy%3CK,+I,+F%3E"class="impl"><ahref="#impl-Sync-for-GroupBy%3CK,+I,+F%3E"class="anchor">§</a><h3class="code-header">impl<K, I, F> !<aclass="trait"href="https://doc.rust-lang.org/1.78.0/core/marker/trait.Sync.html"title="trait core::marker::Sync">Sync</a> for <aclass="struct"href="struct.GroupBy.html"title="struct itertools::structs::GroupBy">GroupBy</a><K, I, F></h3></section><sectionid="impl-Unpin-for-GroupBy%3CK,+I,+F%3E"class="impl"><ahref="#impl-Unpin-for-GroupBy%3CK,+I,+F%3E"class="anchor">§</a><h3class="code-header">impl<K, I, F><aclass="trait"href="https://doc.rust-lang.org/1.78.0/core/marker/trait.Unpin.html"title="trait core::marker::Unpin">Unpin</a> for <aclass="struct"href="struct.GroupBy.html"title="struct itertools::structs::GroupBy">GroupBy</a><K, I, F><divclass="where">where
<I as <aclass="trait"href="https://doc.rust-lang.org/1.78.0/core/iter/traits/iterator/trait.Iterator.html"title="trait core::iter::traits::iterator::Iterator">Iterator</a>>::<aclass="associatedtype"href="https://doc.rust-lang.org/1.78.0/core/iter/traits/iterator/trait.Iterator.html#associatedtype.Item"title="type core::iter::traits::iterator::Iterator::Item">Item</a>: <aclass="trait"href="https://doc.rust-lang.org/1.78.0/core/marker/trait.Unpin.html"title="trait core::marker::Unpin">Unpin</a>,</div></h3></section><sectionid="impl-UnwindSafe-for-GroupBy%3CK,+I,+F%3E"class="impl"><ahref="#impl-UnwindSafe-for-GroupBy%3CK,+I,+F%3E"class="anchor">§</a><h3class="code-header">impl<K, I, F><aclass="trait"href="https://doc.rust-lang.org/1.78.0/core/panic/unwind_safe/trait.UnwindSafe.html"title="trait core::panic::unwind_safe::UnwindSafe">UnwindSafe</a> for <aclass="struct"href="struct.GroupBy.html"title="struct itertools::structs::GroupBy">GroupBy</a><K, I, F><divclass="where">where
<code><ahref="https://doc.rust-lang.org/1.78.0/core/convert/trait.From.html"title="trait core::convert::From">From</a><T> for U</code> chooses to do.</p>
</div></details></div></details><detailsclass="toggle implementors-toggle"><summary><sectionid="impl-IntoEither-for-T"class="impl"><aclass="src rightside"href="../../src/either/into_either.rs.html#64">source</a><ahref="#impl-IntoEither-for-T"class="anchor">§</a><h3class="code-header">impl<T><aclass="trait"href="../../either/into_either/trait.IntoEither.html"title="trait either::into_either::IntoEither">IntoEither</a> for T</h3></section></summary><divclass="impl-items"><detailsclass="toggle method-toggle"open><summary><sectionid="method.into_either"class="method trait-impl"><aclass="src rightside"href="../../src/either/into_either.rs.html#29">source</a><ahref="#method.into_either"class="anchor">§</a><h4class="code-header">fn <ahref="../../either/into_either/trait.IntoEither.html#method.into_either"class="fn">into_either</a>(self, into_left: <aclass="primitive"href="https://doc.rust-lang.org/1.78.0/std/primitive.bool.html">bool</a>) -><aclass="enum"href="../enum.Either.html"title="enum itertools::Either">Either</a><Self, Self><ahref="#"class="tooltip"data-notable-ty="Either<Self, Self>">ⓘ</a></h4></section></summary><divclass='docblock'>Converts <code>self</code> into a <ahref="../enum.Either.html#variant.Left"title="variant itertools::Either::Left"><code>Left</code></a> variant of <ahref="../enum.Either.html"title="enum itertools::Either"><code>Either<Self, Self></code></a>
Converts <code>self</code> into a <ahref="../enum.Either.html#variant.Right"title="variant itertools::Either::Right"><code>Right</code></a> variant of <ahref="../enum.Either.html"title="enum itertools::Either"><code>Either<Self, Self></code></a>
F: <aclass="trait"href="https://doc.rust-lang.org/1.78.0/core/ops/function/trait.FnOnce.html"title="trait core::ops::function::FnOnce">FnOnce</a>(<aclass="primitive"href="https://doc.rust-lang.org/1.78.0/std/primitive.reference.html">&Self</a>) -><aclass="primitive"href="https://doc.rust-lang.org/1.78.0/std/primitive.bool.html">bool</a>,</div></h4></section></summary><divclass='docblock'>Converts <code>self</code> into a <ahref="../enum.Either.html#variant.Left"title="variant itertools::Either::Left"><code>Left</code></a> variant of <ahref="../enum.Either.html"title="enum itertools::Either"><code>Either<Self, Self></code></a>
if <code>into_left(&self)</code> returns <code>true</code>.
Converts <code>self</code> into a <ahref="../enum.Either.html#variant.Right"title="variant itertools::Either::Right"><code>Right</code></a> variant of <ahref="../enum.Either.html"title="enum itertools::Either"><code>Either<Self, Self></code></a>
otherwise. <ahref="../../either/into_either/trait.IntoEither.html#method.into_either_with">Read more</a></div></details></div></details><detailsclass="toggle implementors-toggle"><summary><sectionid="impl-TryFrom%3CU%3E-for-T"class="impl"><aclass="src rightside"href="https://doc.rust-lang.org/1.78.0/src/core/convert/mod.rs.html#805-807">source</a><ahref="#impl-TryFrom%3CU%3E-for-T"class="anchor">§</a><h3class="code-header">impl<T, U><aclass="trait"href="https://doc.rust-lang.org/1.78.0/core/convert/trait.TryFrom.html"title="trait core::convert::TryFrom">TryFrom</a><U> for T<divclass="where">where
U: <aclass="trait"href="https://doc.rust-lang.org/1.78.0/core/convert/trait.Into.html"title="trait core::convert::Into">Into</a><T>,</div></h3></section></summary><divclass="impl-items"><detailsclass="toggle"open><summary><sectionid="associatedtype.Error-1"class="associatedtype trait-impl"><ahref="#associatedtype.Error-1"class="anchor">§</a><h4class="code-header">type <ahref="https://doc.rust-lang.org/1.78.0/core/convert/trait.TryFrom.html#associatedtype.Error"class="associatedtype">Error</a> = <aclass="enum"href="https://doc.rust-lang.org/1.78.0/core/convert/enum.Infallible.html"title="enum core::convert::Infallible">Infallible</a></h4></section></summary><divclass='docblock'>The type returned in the event of a conversion error.</div></details><detailsclass="toggle method-toggle"open><summary><sectionid="method.try_from"class="method trait-impl"><aclass="src rightside"href="https://doc.rust-lang.org/1.78.0/src/core/convert/mod.rs.html#812">source</a><ahref="#method.try_from"class="anchor">§</a><h4class="code-header">fn <ahref="https://doc.rust-lang.org/1.78.0/core/convert/trait.TryFrom.html#tymethod.try_from"class="fn">try_from</a>(value: U) -><aclass="enum"href="https://doc.rust-lang.org/1.78.0/core/result/enum.Result.html"title="enum core::result::Result">Result</a><T, <T as <aclass="trait"href="https://doc.rust-lang.org/1.78.0/core/convert/trait.TryFrom.html"title="trait core::convert::TryFrom">TryFrom</a><U>>::<aclass="associatedtype"href="https://doc.rust-lang.org/1.78.0/core/convert/trait.TryFrom.html#associatedtype.Error"title="type core::convert::TryFrom::Error">Error</a>></h4></section></summary><divclass='docblock'>Performs the conversion.</div></details></div></details><detailsclass="toggle implementors-toggle"><summary><sectionid="impl-TryInto%3CU%3E-for-T"class="impl"><aclass="src rightside"href="https://doc.rust-lang.org/1.78.0/src/core/convert/mod.rs.html#790-792">source</a><ahref="#impl-TryInto%3CU%3E-for-T"class="anchor">§</a><h3class="code-header">impl<T, U><aclass="trait"href="https://doc.rust-lang.org/1.78.0/core/convert/trait.TryInto.html"title="trait core::convert::TryInto">TryInto</a><U> for T<divclass="where">where
U: <aclass="trait"href="https://doc.rust-lang.org/1.78.0/core/convert/trait.TryFrom.html"title="trait core::convert::TryFrom">TryFrom</a><T>,</div></h3></section></summary><divclass="impl-items"><detailsclass="toggle"open><summary><sectionid="associatedtype.Error"class="associatedtype trait-impl"><ahref="#associatedtype.Error"class="anchor">§</a><h4class="code-header">type <ahref="https://doc.rust-lang.org/1.78.0/core/convert/trait.TryInto.html#associatedtype.Error"class="associatedtype">Error</a> = <U as <aclass="trait"href="https://doc.rust-lang.org/1.78.0/core/convert/trait.TryFrom.html"title="trait core::convert::TryFrom">TryFrom</a><T>>::<aclass="associatedtype"href="https://doc.rust-lang.org/1.78.0/core/convert/trait.TryFrom.html#associatedtype.Error"title="type core::convert::TryFrom::Error">Error</a></h4></section></summary><divclass='docblock'>The type returned in the event of a conversion error.</div></details><detailsclass="toggle method-toggle"open><summary><sectionid="method.try_into"class="method trait-impl"><aclass="src rightside"href="https://doc.rust-lang.org/1.78.0/src/core/convert/mod.rs.html#797">source</a><ahref="#method.try_into"class="anchor">§</a><h4class="code-header">fn <ahref="https://doc.rust-lang.org/1.78.0/core/convert/trait.TryInto.html#tymethod.try_into"class="fn">try_into</a>(self) -><aclass="enum"href="https://doc.rust-lang.org/1.78.0/core/result/enum.Result.html"title="enum core::result::Result">Result</a><U, <U as <aclass="trait"href="https://doc.rust-lang.org/1.78.0/core/convert/trait.TryFrom.html"title="trait core::convert::TryFrom">TryFrom</a><T>>::<aclass="associatedtype"href="https://doc.rust-lang.org/1.78.0/core/convert/trait.TryFrom.html#associatedtype.Error"title="type core::convert::TryFrom::Error">Error</a>></h4></section></summary><divclass='docblock'>Performs the conversion.</div></details></div></details></div><scripttype="text/json"id="notable-traits-data">{"Either<Self,Self>":"<h3>Notabletraitsfor<code><aclass=\"enum\"href=\"../enum.Either.html\"title=\"enumitertools::Either\">Either</a><L,R></code></h3><pre><code><divclass=\"where\">impl<L,R><aclass=\"trait\"href=\"https://doc.rust-lang.org/1.78.0/core/future/future/trait.Future.html\"title=\"traitcore::future::future::Future\">Future</a>for<aclass=\"enum\"href=\"../enum.Either.html\"title=\"enumitertools::Either\">Either</a><L,R><divclass=\"where\">where\nL:<aclass=\"trait\"href=\"https://doc.rust-lang.org/1.78.0/core/future/future/trait.Future.html\"title=\"traitcore::future::future::Future\">Future</a>,\nR:<aclass=\"trait\"href=\"https://doc.rust-lang.org/1.78.0/core/future/future/trait.Future.html\"title=\"traitcore::future::future::Future\">Future</a><Output=<Las<aclass=\"trait\"href=\"https://doc.rust-lang.org/1.78.0/core/future/future/trait.Future.html\"title=\"traitcore::future::future::Future\">Future</a>>::<aclass=\"associatedtype\"href=\"https://doc.rust-lang.org/1.78.0/core/future/future/trait.Future.html#associatedtype.Output\"title=\"typecore::future::future::Future::Output\">Output</a>>,</div></div><divclass=\"where\">type<ahref=\"https://doc.rust-lang.org/1.78.0/core/future/future/trait.Future.html#associatedtype.Output\"class=\"associatedtype\">Output</a>=<Las<aclass=\"trait\"href=\"https://doc.rust-lang.org/1.78.0/core/future/future/trait.Future.html\"title=\"traitcore::future::future::Future\">Future</a>>::<aclass=\"associatedtype\"href=\"https://doc.rust-lang.org/1.78.0/core/future/future/trait.Future.html#associatedtype.Output\"title=\"typecore::future::future::Future::Output\">Output</a>;</div><divclass=\"where\">impl<L,R><aclass=\"trait\"href=\"https://doc.rust-lang.org/1.78.0/std/io/trait.Write.html\"title=\"traitstd::io::Write\">Write</a>for<aclass=\"enum\"href=\"../enum.Either.html\"title=\"enumitertools::Either\">Either</a><L,R><divclass=\"where\">where\nL:<aclass=
