Metadata-Version: 2.1
Name: orderedstructs
Version: 0.3.5
Summary: Contains a variety of ordered structures, in particular a SkipList.
Home-page: https://github.com/paulross/skiplist
Author: Paul Ross
Author-email: apaulross@gmail.com
License: MIT License
Description: # SkipList
        
        This project contains a SkipList implementation in C++ with Python bindings.
        
        A SkipList behaves as an always sorted list with, typically, O(log(n)) cost for insertion, look-up and removal.
        This makes it ideal for such operations as computing the rolling median of a large dataset.
        
        See the full documentation on this project at [ReadTheDocs](http://skiplist.readthedocs.io/en/latest/index.html).
        
        A SkipList is implemented as a singly linked list of ordered nodes where each node participates in a subset of, sparser, linked lists.
        These additional 'sparse' linked lists provide rapid indexing and mutation of the underlying linked list.
        It is a probabilistic data structure using a random function to determine how many 'sparse' linked lists any particular node participates in.
        As such SkipList is an alternative to binary tree, Wikipedia has a introductory page on [SkipLists](<https://en.wikipedia.org/wiki/Skip_list>).
        
        An advantage claimed for SkipLists are that the insert and remove logic is simpler (however I do not subscribe to this).
        The drawbacks of a SkipList include its larger space requirements and its O(log(N)) lookup behaviour compared to other, more restricted and specialised, data structures that may have either faster runtime behaviour or lower space requirements or both.
        
        This project contains a SkipList implementation in C++ with Python bindings with:
        
        * No capacity restrictions apart from available memory.
        * Works with any C++ type <T> that has meaningful comparison operators.
        * The C++ SkipList can be compiled as thread safe.
        * The Python SkipList is thread safe.
        * The SkipList has exhaustive internal integrity checks.
        * Python SkipLists can be long/float/bytes/object types, the latter can have user defined comparison functions.
        * With Python 3.8+ SkipLists can be combined with the [multiprocessing.shared_memory](https://docs.python.org/3/library/multiprocessing.shared_memory.html#module-multiprocessing.shared_memory) module for concurrent operation on large arrays.
          For example [concurrent rolling medians](https://skiplist.readthedocs.io/en/latest/rolling_median.html#rolling-median-in-python-with-multiprocessing-shared-memory) which speed up near linearly with the number of cores.
        * The implementation is extensively performance tested in C++ and Python.
        
        
        There are a some novel features to this implementation:
        
        * A SkipList is a probabilistic data structure but we have deterministic tests that work for any (sane) random number generator. See [Testing a Probabilistic Structure](http://skiplist.readthedocs.io/en/latest/test_notes.html#testing-a-probabilistic-structure)
        * This SkipList can dynamically generate visualisations of its current internal state. See [Visualising a Skip List](http://skiplist.readthedocs.io/en/latest/visualisations.html#skiplist-visualisation-label)
        
        # Credits
        
        Originally written by Paul Ross with credits to: Wilfred Hughes (AHL), Luke Sewell (AHL) and Terry Tsantagoeds (AHL).
        
        
        # Installation
        
        ## C++
        
        This SkipList requires:
        
        * A C++11 compiler.
        * ``-I<skiplist>/src/cpp`` as an include path.
        * ``<skiplist>/src/cpp/SkipList.cpp`` to be compiled/linked.
        * The macro ``SKIPLIST_THREAD_SUPPORT`` set if you want a thread safe SkipList using C++ mutexes.
        
        ## Python
        
        This SkipList version supports Python 3.6, 3.7, 3.8, 3.9 (and, probably, some earlier Python 3 versions).
        Earlier versions supported Python 2.7, this version might still do that.
        
        ### From PyPi
        
            $ pip install orderedstructs
        
        ### From source
        
            $ git clone https://github.com/paulross/skiplist.git
            $ cd <skiplist>
            $ python setup.py install
        
        
        # Testing
        
        
        This SkipList has extensive tests for correctness and performance.
        
        ## C++
        
        To run all the C++ functional and performance tests:
        
            $ cd <skiplist>/src/cpp
            $ make release
            $ ./SkipList_R.exe
        
        To run the C++ functional tests with agressive internal integrity checks:
        
            $ cd <skiplist>/src/cpp
            $ make debug
            $ ./SkipList_D.exe
        
        To run all the C++ functional and performance tests for a thread safe SkipList:
        
            $ cd <skiplist>/src/cpp
            $ make release CXXFLAGS=-DSKIPLIST_THREAD_SUPPORT
            $ ./SkipList_R.exe
        
        
        ## Python
        
        Testing requires ``pytest`` and ``hypothesis``:
        
        To run all the C++ functional and performance tests:
        
            $ cd <skiplist>
            $ py.test -vs tests/
        
        
        # Examples
        
        Here are some examples of using a SkipList in your code:
        
        ## C++
        
        
            #include "SkipList.h"
                
            // Declare with any type that has sane comparison.
            OrderedStructs::SkipList::HeadNode<double> sl;
            
            sl.insert(42.0);
            sl.insert(21.0);
            sl.insert(84.0);
            
            sl.has(42.0) // true
            sl.size()    // 3
            sl.at(1)     // 42.0, throws OrderedStructs::SkipList::IndexError if index out of range
        
            sl.remove(21.0); // throws OrderedStructs::SkipList::ValueError if value not present
            
            sl.size()    // 2
            sl.at(1)     // 84.0
        
        The C++ SkipList is thread safe when compiled with the macro ``SKIPLIST_THREAD_SUPPORT``, then a SkipList can then be shared across threads:
        
            #include <thread>
            #include <vector>
            
            #include "SkipList.h"
        
            void do_something(OrderedStructs::SkipList::HeadNode<double> *pSkipList) {
                // Insert/remove items into *pSkipList
                // Read items inserted by other threads.
            }
        
            OrderedStructs::SkipList::HeadNode<double> sl;
            std::vector<std::thread> threads;
        
            for (size_t i = 0; i < thread_count; ++i) {
                threads.push_back(std::thread(do_something, &sl));
            }
            for (auto &t: threads) {
                t.join();
            }
            // The SkipList now contains the totality of the thread actions.
        
        
        ## Python
        
        An example of using a SkipList of always ordered floats:
        
            import orderedstructs
            
            # Declare with a type. Supported types are long/float/bytes/object.
            sl = orderedstructs.SkipList(float)
            
            sl.insert(42.0)
            sl.insert(21.0)
            sl.insert(84.0)
            
            sl.has(42.0) # True
            sl.size()    # 3
            sl.at(1)     # 42.0
        
            sl.has(42.0) # True
            sl.size()    # 3
            sl.at(1)     # 42.0, raises IndexError if index out of range
        
            sl.remove(21.0); # raises ValueError if value not present
            
            sl.size()    # 2
            sl.at(1)     # 84.0
        
        The Python SkipList can be used with user defined objects with a user defined sort order.
        In this example the last name of the person takes precedence over the first name:
        
            import functools
            
            @functools.total_ordering
            class Person:
                """Simple example of ordering based on last name/first name."""
                def __init__(self, first_name, last_name):
                    self.first_name = first_name
                    self.last_name = last_name
            
                def __eq__(self, other):
                    try:
                        return self.last_name == other.last_name and self.first_name == other.first_name
                    except AttributeError:
                        return NotImplemented
        
                def __lt__(self, other):
                    try:
                        return self.last_name < other.last_name or self.first_name < other.first_name
                    except AttributeError:
                        return NotImplemented
            
                def __str__(self):
                    return '{}, {}'.format(self.last_name, self.first_name)
        
            import orderedstructs
            
            sl = orderedstructs.SkipList(object)
        
            sl.insert(Person('Peter', 'Pan'))
            sl.insert(Person('Alan', 'Pan'))
            assert sl.size() == 2
            assert str(sl.at(0)) == 'Pan, Alan' 
            assert str(sl.at(1)) == 'Pan, Peter' 
        
        
        The Python SkipList is thread safe when using any acceptable Python type even if that type has user defined comparison methods.
        This uses Pythons mutex machinery which is independent of C++ mutexes.
        
        
        # History
        
        ## 0.3.5 (2021-05-02)
        
        * Fix uncaught exception when trying to remove a NaN.
        
        ## 0.3.4 (2021-04-28)
        
        * Improve documentation mainly around multiprocessing.shared_memory and tests.
        
        ## 0.3.3 (2021-03-25)
        
        * Add Python benchmarks, fix some build issues.
        
        ## 0.3.2 (2021-03-18)
        
        * Fix lambda issues with Python 3.8, 3.9.
        
        ## 0.3.1 (2021-03-17)
        
        * Support Python 3.7, 3.8, 3.9.
        
        ## 0.3.0 (2017-08-18)
        
        * Public release.
        * Allows storing of ``PyObject*`` and rich comparison.
        
        ## 0.2.0
        
        Python module now named ``orderedstructs``.
        
        # 0.1.0
        
        Initial release.
        
        
Keywords: orderedstructs,SkipList
Platform: UNKNOWN
Classifier: Development Status :: 2 - Pre-Alpha
Classifier: Intended Audience :: Developers
Classifier: License :: OSI Approved :: MIT License
Classifier: Natural Language :: English
Classifier: Programming Language :: Python :: 2
Classifier: Programming Language :: Python :: 2.7
Classifier: Programming Language :: Python :: 3
Classifier: Programming Language :: Python :: 3.3
Classifier: Programming Language :: Python :: 3.4
Classifier: Programming Language :: Python :: 3.5
Classifier: Programming Language :: Python :: 3.6
Classifier: Programming Language :: Python :: 3.7
Classifier: Programming Language :: Python :: 3.8
Classifier: Programming Language :: Python :: 3.9
Description-Content-Type: text/markdown
