[Lemon-commits] Balazs Dezso: Porting radix sorts from SVN #3509
Lemon HG
hg at lemon.cs.elte.hu
Thu Jan 8 18:32:49 CET 2009
details: http://lemon.cs.elte.hu/hg/lemon/rev/4f7224faf3bd
changeset: 464:4f7224faf3bd
user: Balazs Dezso <deba [at] inf.elte.hu>
date: Fri Oct 17 23:55:18 2008 +0200
description:
Porting radix sorts from SVN #3509
diffstat:
5 files changed, 635 insertions(+)
lemon/Makefile.am | 1
lemon/radix_sort.h | 484 +++++++++++++++++++++++++++++++++++++++++++++++
test/CMakeLists.txt | 1
test/Makefile.am | 2
test/radix_sort_test.cc | 147 ++++++++++++++
diffs (truncated from 682 to 300 lines):
diff --git a/lemon/Makefile.am b/lemon/Makefile.am
--- a/lemon/Makefile.am
+++ b/lemon/Makefile.am
@@ -36,6 +36,7 @@
lemon/maps.h \
lemon/math.h \
lemon/path.h \
+ lemon/radix_sort.h \
lemon/random.h \
lemon/smart_graph.h \
lemon/time_measure.h \
diff --git a/lemon/radix_sort.h b/lemon/radix_sort.h
new file mode 100644
--- /dev/null
+++ b/lemon/radix_sort.h
@@ -0,0 +1,484 @@
+/* -*- C++ -*-
+ *
+ * This file is a part of LEMON, a generic C++ optimization library
+ *
+ * Copyright (C) 2003-2008
+ * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
+ * (Egervary Research Group on Combinatorial Optimization, EGRES).
+ *
+ * Permission to use, modify and distribute this software is granted
+ * provided that this copyright notice appears in all copies. For
+ * precise terms see the accompanying LICENSE file.
+ *
+ * This software is provided "AS IS" with no warranty of any kind,
+ * express or implied, and with no claim as to its suitability for any
+ * purpose.
+ *
+ */
+
+#ifndef RADIX_SORT_H
+#define RADIX_SORT_H
+
+/// \ingroup auxalg
+/// \file
+/// \brief Radix sort
+///
+/// Linear time sorting algorithms
+
+#include <vector>
+#include <limits>
+#include <iterator>
+#include <algorithm>
+
+namespace lemon {
+
+ namespace _radix_sort_bits {
+
+ template <typename Value>
+ struct Identity {
+ const Value& operator()(const Value& val) {
+ return val;
+ }
+ };
+
+
+ template <typename Value, typename Iterator, typename Functor>
+ Iterator radixSortPartition(Iterator first, Iterator last,
+ Functor functor, Value mask) {
+ while (first != last && !(functor(*first) & mask)) {
+ ++first;
+ }
+ if (first == last) {
+ return first;
+ }
+ --last;
+ while (first != last && (functor(*last) & mask)) {
+ --last;
+ }
+ if (first == last) {
+ return first;
+ }
+ std::iter_swap(first, last);
+ ++first;
+ if (!(first < last)) {
+ return first;
+ }
+ while (true) {
+ while (!(functor(*first) & mask)) {
+ ++first;
+ }
+ --last;
+ while (functor(*last) & mask) {
+ --last;
+ }
+ if (!(first < last)) {
+ return first;
+ }
+ std::iter_swap(first, last);
+ ++first;
+ }
+ }
+
+ template <typename Iterator, typename Functor>
+ Iterator radixSortSignPartition(Iterator first, Iterator last,
+ Functor functor) {
+ while (first != last && functor(*first) < 0) {
+ ++first;
+ }
+ if (first == last) {
+ return first;
+ }
+ --last;
+ while (first != last && functor(*last) >= 0) {
+ --last;
+ }
+ if (first == last) {
+ return first;
+ }
+ std::iter_swap(first, last);
+ ++first;
+ if (!(first < last)) {
+ return first;
+ }
+ while (true) {
+ while (functor(*first) < 0) {
+ ++first;
+ }
+ --last;
+ while (functor(*last) >= 0) {
+ --last;
+ }
+ if (!(first < last)) {
+ return first;
+ }
+ std::iter_swap(first, last);
+ ++first;
+ }
+ }
+
+ template <typename Value, typename Iterator, typename Functor>
+ void radixIntroSort(Iterator first, Iterator last,
+ Functor functor, Value mask) {
+ while (mask != 0 && last - first > 1) {
+ Iterator cut = radixSortPartition(first, last, functor, mask);
+ mask >>= 1;
+ radixIntroSort(first, cut, functor, mask);
+ first = cut;
+ }
+ }
+
+ template <typename Value, typename Iterator, typename Functor>
+ void radixSignedSort(Iterator first, Iterator last, Functor functor) {
+
+ Iterator cut = radixSortSignPartition(first, last, functor);
+
+ Value mask;
+ int max_digit;
+ Iterator it;
+
+ mask = ~0; max_digit = 0;
+ for (it = first; it != cut; ++it) {
+ while ((mask & functor(*it)) != mask) {
+ ++max_digit;
+ mask <<= 1;
+ }
+ }
+ radixIntroSort(first, cut, functor, 1 << max_digit);
+
+ mask = 0; max_digit = 0;
+ for (it = cut; it != last; ++it) {
+ while ((mask | functor(*it)) != mask) {
+ ++max_digit;
+ mask <<= 1; mask |= 1;
+ }
+ }
+ radixIntroSort(cut, last, functor, 1 << max_digit);
+ }
+
+ template <typename Value, typename Iterator, typename Functor>
+ void radixUnsignedSort(Iterator first, Iterator last, Functor functor) {
+
+ Value mask = 0;
+ int max_digit = 0;
+
+ Iterator it;
+ for (it = first; it != last; ++it) {
+ while ((mask | functor(*it)) != mask) {
+ ++max_digit;
+ mask <<= 1; mask |= 1;
+ }
+ }
+ radixIntroSort(first, last, functor, 1 << max_digit);
+ }
+
+
+ template <typename Value,
+ bool sign = std::numeric_limits<Value>::is_signed >
+ struct RadixSortSelector {
+ template <typename Iterator, typename Functor>
+ static void sort(Iterator first, Iterator last, Functor functor) {
+ radixSignedSort<Value>(first, last, functor);
+ }
+ };
+
+ template <typename Value>
+ struct RadixSortSelector<Value, false> {
+ template <typename Iterator, typename Functor>
+ static void sort(Iterator first, Iterator last, Functor functor) {
+ radixUnsignedSort<Value>(first, last, functor);
+ }
+ };
+
+ }
+
+ /// \ingroup auxalg
+ ///
+ /// \brief Sorts the STL compatible range into ascending order.
+ ///
+ /// The \c radixSort sorts the STL compatible range into ascending
+ /// order. The radix sort algorithm can sort the items which mapped
+ /// to an integer with an adaptable unary function \c functor and the
+ /// order will be ascending by these mapped values. As function
+ /// specialization it is possible to use a normal function instead
+ /// of the functor object or if the functor is not given it will use
+ /// an identity function instead.
+ ///
+ /// This implemented radix sort is a special quick sort which pivot
+ /// value is choosen to partite the items on the next
+ /// bit. Therefore, let be \c c the maximal capacity and \c n the
+ /// number of the items in the container, the time complexity of the
+ /// algorithm is \f$ O(\log(c)n) \f$ and the additional space
+ /// complexity is \f$ O(\log(c)) \f$.
+ ///
+ /// \param first The begin of the given range.
+ /// \param last The end of the given range.
+ /// \param functor An adaptible unary function or a normal function
+ /// which maps the items to any integer type which can be either
+ /// signed or unsigned.
+ template <typename Iterator, typename Functor>
+ void radixSort(Iterator first, Iterator last, Functor functor) {
+ using namespace _radix_sort_bits;
+ typedef typename Functor::result_type Value;
+ RadixSortSelector<Value>::sort(first, last, functor);
+ }
+
+ template <typename Iterator, typename Value, typename Key>
+ void radixSort(Iterator first, Iterator last, Value (*functor)(Key)) {
+ using namespace _radix_sort_bits;
+ RadixSortSelector<Value>::sort(first, last, functor);
+ }
+
+ template <typename Iterator, typename Value, typename Key>
+ void radixSort(Iterator first, Iterator last, Value& (*functor)(Key)) {
+ using namespace _radix_sort_bits;
+ RadixSortSelector<Value>::sort(first, last, functor);
+ }
+
+ template <typename Iterator, typename Value, typename Key>
+ void radixSort(Iterator first, Iterator last, Value (*functor)(Key&)) {
+ using namespace _radix_sort_bits;
+ RadixSortSelector<Value>::sort(first, last, functor);
+ }
+
+ template <typename Iterator, typename Value, typename Key>
+ void radixSort(Iterator first, Iterator last, Value& (*functor)(Key&)) {
+ using namespace _radix_sort_bits;
+ RadixSortSelector<Value>::sort(first, last, functor);
+ }
+
+ template <typename Iterator>
+ void radixSort(Iterator first, Iterator last) {
+ using namespace _radix_sort_bits;
+ typedef typename std::iterator_traits<Iterator>::value_type Value;
+ RadixSortSelector<Value>::sort(first, last, Identity<Value>());
+ }
+
+ namespace _radix_sort_bits {
+
+ template <typename Value>
+ unsigned char valueByte(Value value, int byte) {
+ return value >> (std::numeric_limits<unsigned char>::digits * byte);
+ }
+
+ template <typename Functor, typename Key>
+ void counterIntroSort(Key *first, Key *last, Key *target,
+ int byte, Functor functor) {
+ const int size =
+ unsigned(std::numeric_limits<unsigned char>::max()) + 1;
+ std::vector<int> counter(size);
+ for (int i = 0; i < size; ++i) {
+ counter[i] = 0;
+ }
+ Key *it = first;
+ while (first != last) {
+ ++counter[valueByte(functor(*first), byte)];
+ ++first;
+ }
+ int prev, num = 0;
+ for (int i = 0; i < size; ++i) {
+ prev = num;
+ num += counter[i];
+ counter[i] = prev;
+ }
+ while (it != last) {
+ target[counter[valueByte(functor(*it), byte)]++] = *it;
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