Struct permutator::XPermutationIterator
source · [−]pub struct XPermutationIterator<'a, F, T> where
F: FnMut(&[&T]) -> bool,
T: 'a, { /* private fields */ }
Expand description
A lexicographic ordered permutation based on “Algoritm X” published by Donald E. Knuth. page 20.
If order is not important, consider using heap permutation struct instead. This struct is a bit slower (about 10%) than heap permutation in uncontroll test environment.
The algorithm work by simulate tree traversal where some branch can be
skip altogether. This is archive by provided t
function that take
slice of partial result as parameter. If the partial result needed to be skip,
return false. Otherwise, return true and the algorithm will call this function
again when the branch is descended deeper. For example: First call to t
may
contain [1]. If t
return true, it will be called again with [1, 2]. If it
return true, and there’s leaf node, cb will be called with [1, 2]. On the other hand,
if t
is called with [1, 3] and it return false, it won’t call the callback.
If t
is called with [4] and it return false, it won’t try to traverse deeper even
if there’re [4, 5], or [4, 6]. It will skip altogether and call t
with [7].
The process goes on until every branch is traversed.
Example
Get all lexicalgraphic ordered permutation
use permutator::XPermutationIterator;
let data = vec![1, 2, 3, 4];
let mut counter = 0;
XPermutationIterator::new(&data, |_| true).for_each(|p| {
println!("{:?}", p);
counter += 1;
});
assert_eq!(factorial(data.len()), counter);
Skip all permutation that has 1
in first element.
use permutator::XPermutationIterator;
let data : Vec<u8> = vec![1, 2, 3, 4];
let mut counter = 0;
XPermutationIterator::new(&data, |f| {
*f[0] != 1u8 // filter all permutation that start with 1
}).for_each(|p| {
println!("{:?}", p);
counter += 1;
});
assert_eq!(factorial(data.len()) - factorial(data.len() - 1), counter);
Multi-threads permutation example
use permutator::XpermutationIterator;
use std::time::{Instant};
let data : Vec<usize> = (0..4).map(|num| num).collect();
let threads = 2;
let chunk = data.len() / threads;
let (tx, rx) = mpsc::channel();
for i in 0..threads {
let start = chunk * i;
let end = match i {
j if j == threads - 1 => data.len(), // last thread handle remaining work
_ => chunk * (i + 1)
};
let l_dat = data.to_owned(); // copy data for each thread
let end_sig = tx.clone();
thread::spawn(move || {
let timer = Instant::now();
let perm = XPermutationIterator::new(
&l_dat,
|v| *v[0] >= start && *v[0] < end // skip branch that is outside the start/end
);
let mut counter = 0u64;
for p in perm {
// each permutation is stored in p
counter += 1;
}
end_sig.send(i).unwrap();
});
}
let main = thread::spawn(move || { // main thread
let mut counter = 0;
while counter < threads {
let i = rx.recv().unwrap();
// do something
counter += 1;
}
});
main.join().unwrap();
Implementations
pub fn new(data: &'a [T], t: F) -> XPermutationIterator<'_, F, T>ⓘ
pub fn new(data: &'a [T], t: F) -> XPermutationIterator<'_, F, T>ⓘ
Construct new XPermutationIterator object.
Parameters
data : &[T]
- A data used for generate permutation.t : FnMut(&[&T])
- A function that if return true, will make algorithm continue traversing the tree. Otherwise, the entire branch will be skip.
Trait Implementations
impl<'a, F, T> ExactSizeIterator for XPermutationIterator<'a, F, T> where
F: FnMut(&[&T]) -> bool,
T: 'a,
impl<'a, F, T> ExactSizeIterator for XPermutationIterator<'a, F, T> where
F: FnMut(&[&T]) -> bool,
T: 'a,
Advances the iterator and returns the next value. Read more
Returns the bounds on the remaining length of the iterator. Read more
Consumes the iterator, counting the number of iterations and returning it. Read more
Consumes the iterator, returning the last element. Read more
iter_advance_by
)Advances the iterator by n
elements. Read more
Returns the n
th element of the iterator. Read more
Creates an iterator starting at the same point, but stepping by the given amount at each iteration. Read more
1.0.0 · sourcefn chain<U>(self, other: U) -> Chain<Self, <U as IntoIterator>::IntoIter> where
U: IntoIterator<Item = Self::Item>,
fn chain<U>(self, other: U) -> Chain<Self, <U as IntoIterator>::IntoIter> where
U: IntoIterator<Item = Self::Item>,
Takes two iterators and creates a new iterator over both in sequence. Read more
1.0.0 · sourcefn zip<U>(self, other: U) -> Zip<Self, <U as IntoIterator>::IntoIter> where
U: IntoIterator,
fn zip<U>(self, other: U) -> Zip<Self, <U as IntoIterator>::IntoIter> where
U: IntoIterator,
‘Zips up’ two iterators into a single iterator of pairs. Read more
iter_intersperse
)Creates a new iterator which places a copy of separator
between adjacent
items of the original iterator. Read more
fn intersperse_with<G>(self, separator: G) -> IntersperseWith<Self, G> where
G: FnMut() -> Self::Item,
fn intersperse_with<G>(self, separator: G) -> IntersperseWith<Self, G> where
G: FnMut() -> Self::Item,
iter_intersperse
)Creates a new iterator which places an item generated by separator
between adjacent items of the original iterator. Read more
Takes a closure and creates an iterator which calls that closure on each element. Read more
Calls a closure on each element of an iterator. Read more
Creates an iterator which uses a closure to determine if an element should be yielded. Read more
Creates an iterator that both filters and maps. Read more
Creates an iterator which gives the current iteration count as well as the next value. Read more
Creates an iterator that yields elements based on a predicate. Read more
Creates an iterator that both yields elements based on a predicate and maps. Read more
Creates an iterator that skips the first n
elements. Read more
Creates an iterator that yields the first n
elements, or fewer
if the underlying iterator ends sooner. Read more
Creates an iterator that works like map, but flattens nested structure. Read more
Creates an iterator that flattens nested structure. Read more
Does something with each element of an iterator, passing the value on. Read more
Borrows an iterator, rather than consuming it. Read more
Transforms an iterator into a collection. Read more
Consumes an iterator, creating two collections from it. Read more
fn partition_in_place<'a, T, P>(self, predicate: P) -> usize where
T: 'a,
Self: DoubleEndedIterator<Item = &'a mut T>,
P: FnMut(&T) -> bool,
fn partition_in_place<'a, T, P>(self, predicate: P) -> usize where
T: 'a,
Self: DoubleEndedIterator<Item = &'a mut T>,
P: FnMut(&T) -> bool,
iter_partition_in_place
)Reorders the elements of this iterator in-place according to the given predicate,
such that all those that return true
precede all those that return false
.
Returns the number of true
elements found. Read more
iter_is_partitioned
)Checks if the elements of this iterator are partitioned according to the given predicate,
such that all those that return true
precede all those that return false
. Read more
An iterator method that applies a function as long as it returns successfully, producing a single, final value. Read more
An iterator method that applies a fallible function to each item in the iterator, stopping at the first error and returning that error. Read more
Folds every element into an accumulator by applying an operation, returning the final result. Read more
Reduces the elements to a single one, by repeatedly applying a reducing operation. Read more
iterator_try_reduce
)Reduces the elements to a single one by repeatedly applying a reducing operation. If the closure returns a failure, the failure is propagated back to the caller immediately. Read more
Tests if every element of the iterator matches a predicate. Read more
Tests if any element of the iterator matches a predicate. Read more
Searches for an element of an iterator that satisfies a predicate. Read more
Applies function to the elements of iterator and returns the first non-none result. Read more
try_find
)Applies function to the elements of iterator and returns the first true result or the first error. Read more
Searches for an element in an iterator, returning its index. Read more
1.0.0 · sourcefn rposition<P>(&mut self, predicate: P) -> Option<usize> where
P: FnMut(Self::Item) -> bool,
Self: ExactSizeIterator + DoubleEndedIterator,
fn rposition<P>(&mut self, predicate: P) -> Option<usize> where
P: FnMut(Self::Item) -> bool,
Self: ExactSizeIterator + DoubleEndedIterator,
Searches for an element in an iterator from the right, returning its index. Read more
Returns the maximum element of an iterator. Read more
Returns the minimum element of an iterator. Read more
Returns the element that gives the maximum value from the specified function. Read more
Returns the element that gives the maximum value with respect to the specified comparison function. Read more
Returns the element that gives the minimum value from the specified function. Read more
Returns the element that gives the minimum value with respect to the specified comparison function. Read more
Reverses an iterator’s direction. Read more
Converts an iterator of pairs into a pair of containers. Read more
Creates an iterator which copies all of its elements. Read more
Repeats an iterator endlessly. Read more
Sums the elements of an iterator. Read more
Iterates over the entire iterator, multiplying all the elements Read more
Lexicographically compares the elements of this Iterator
with those
of another. Read more
fn cmp_by<I, F>(self, other: I, cmp: F) -> Ordering where
I: IntoIterator,
F: FnMut(Self::Item, <I as IntoIterator>::Item) -> Ordering,
fn cmp_by<I, F>(self, other: I, cmp: F) -> Ordering where
I: IntoIterator,
F: FnMut(Self::Item, <I as IntoIterator>::Item) -> Ordering,
iter_order_by
)Lexicographically compares the elements of this Iterator
with those
of another with respect to the specified comparison function. Read more
1.5.0 · sourcefn partial_cmp<I>(self, other: I) -> Option<Ordering> where
I: IntoIterator,
Self::Item: PartialOrd<<I as IntoIterator>::Item>,
fn partial_cmp<I>(self, other: I) -> Option<Ordering> where
I: IntoIterator,
Self::Item: PartialOrd<<I as IntoIterator>::Item>,
Lexicographically compares the elements of this Iterator
with those
of another. Read more
fn partial_cmp_by<I, F>(self, other: I, partial_cmp: F) -> Option<Ordering> where
I: IntoIterator,
F: FnMut(Self::Item, <I as IntoIterator>::Item) -> Option<Ordering>,
fn partial_cmp_by<I, F>(self, other: I, partial_cmp: F) -> Option<Ordering> where
I: IntoIterator,
F: FnMut(Self::Item, <I as IntoIterator>::Item) -> Option<Ordering>,
iter_order_by
)Lexicographically compares the elements of this Iterator
with those
of another with respect to the specified comparison function. Read more
1.5.0 · sourcefn eq<I>(self, other: I) -> bool where
I: IntoIterator,
Self::Item: PartialEq<<I as IntoIterator>::Item>,
fn eq<I>(self, other: I) -> bool where
I: IntoIterator,
Self::Item: PartialEq<<I as IntoIterator>::Item>,
fn eq_by<I, F>(self, other: I, eq: F) -> bool where
I: IntoIterator,
F: FnMut(Self::Item, <I as IntoIterator>::Item) -> bool,
fn eq_by<I, F>(self, other: I, eq: F) -> bool where
I: IntoIterator,
F: FnMut(Self::Item, <I as IntoIterator>::Item) -> bool,
iter_order_by
)1.5.0 · sourcefn ne<I>(self, other: I) -> bool where
I: IntoIterator,
Self::Item: PartialEq<<I as IntoIterator>::Item>,
fn ne<I>(self, other: I) -> bool where
I: IntoIterator,
Self::Item: PartialEq<<I as IntoIterator>::Item>,
1.5.0 · sourcefn lt<I>(self, other: I) -> bool where
I: IntoIterator,
Self::Item: PartialOrd<<I as IntoIterator>::Item>,
fn lt<I>(self, other: I) -> bool where
I: IntoIterator,
Self::Item: PartialOrd<<I as IntoIterator>::Item>,
Determines if the elements of this Iterator
are lexicographically
less than those of another. Read more
1.5.0 · sourcefn le<I>(self, other: I) -> bool where
I: IntoIterator,
Self::Item: PartialOrd<<I as IntoIterator>::Item>,
fn le<I>(self, other: I) -> bool where
I: IntoIterator,
Self::Item: PartialOrd<<I as IntoIterator>::Item>,
Determines if the elements of this Iterator
are lexicographically
less or equal to those of another. Read more
1.5.0 · sourcefn gt<I>(self, other: I) -> bool where
I: IntoIterator,
Self::Item: PartialOrd<<I as IntoIterator>::Item>,
fn gt<I>(self, other: I) -> bool where
I: IntoIterator,
Self::Item: PartialOrd<<I as IntoIterator>::Item>,
Determines if the elements of this Iterator
are lexicographically
greater than those of another. Read more
1.5.0 · sourcefn ge<I>(self, other: I) -> bool where
I: IntoIterator,
Self::Item: PartialOrd<<I as IntoIterator>::Item>,
fn ge<I>(self, other: I) -> bool where
I: IntoIterator,
Self::Item: PartialOrd<<I as IntoIterator>::Item>,
Determines if the elements of this Iterator
are lexicographically
greater than or equal to those of another. Read more
is_sorted
)Checks if the elements of this iterator are sorted. Read more
is_sorted
)Checks if the elements of this iterator are sorted using the given comparator function. Read more
fn is_sorted_by_key<F, K>(self, f: F) -> bool where
F: FnMut(Self::Item) -> K,
K: PartialOrd<K>,
fn is_sorted_by_key<F, K>(self, f: F) -> bool where
F: FnMut(Self::Item) -> K,
K: PartialOrd<K>,
is_sorted
)Checks if the elements of this iterator are sorted using the given key extraction function. Read more