SkipList | A Java implementation of skip list 跳表的Java语言实现 | Learning library

 by   MottoX Java Version: Current License: MIT

kandi X-RAY | SkipList Summary

kandi X-RAY | SkipList Summary

SkipList is a Java library typically used in Tutorial, Learning, Example Codes applications. SkipList has no bugs, it has no vulnerabilities, it has build file available, it has a Permissive License and it has low support. You can download it from GitHub.

Skip lists are data structures that use probabilistic balancing rather than strictly enforced balancing. As a result, the algorithms for insertion and deletion in skip lists are much simpler and significantly faster than equivalent algorithms for balanced trees. 跳表是90年代由William Pugh发明的一种概率平衡数据结构。跳表的平衡是一种基于随机的非严格平衡。它完全基于链表实现,而不涉及树的结构,和普通的平衡树相比, 跳表的新增和删除操作实现相对简单很多。跳表的核心思想就是将扁平的列表进行分层,每个节点在插入的时候会生成一个随机的层数,基于此随机的层数与跳表中相邻的数据连接。 跳表的增删改查操作具有O(log N)的均摊复杂度。.

            kandi-support Support

              SkipList has a low active ecosystem.
              It has 27 star(s) with 14 fork(s). There are 3 watchers for this library.
              It had no major release in the last 6 months.
              There are 0 open issues and 1 have been closed. There are no pull requests.
              It has a neutral sentiment in the developer community.
              The latest version of SkipList is current.

            kandi-Quality Quality

              SkipList has no bugs reported.

            kandi-Security Security

              SkipList has no vulnerabilities reported, and its dependent libraries have no vulnerabilities reported.

            kandi-License License

              SkipList is licensed under the MIT License. This license is Permissive.
              Permissive licenses have the least restrictions, and you can use them in most projects.

            kandi-Reuse Reuse

              SkipList releases are not available. You will need to build from source code and install.
              Build file is available. You can build the component from source.

            Top functions reviewed by kandi - BETA

            kandi has reviewed SkipList and discovered the below as its top functions. This is intended to give you an instant insight into SkipList implemented functionality, and help decide if they suit your requirements.
            • Associates the specified value with the specified key
            • Generate a random level
            • Compares the given key with the given key
            • Links a node at a given level
            • Convenience method to check equality
            • Returns null if the node is not a data node
            • Check if a node is a data node
            • Finds the node with the given key
            • Returns the highest key currently active
            • Returns the last node
            • Creates an iterator for the value iterator
            • Returns an entry iterator over the entries in this node
            • Returns the lowest key currently present in this skip list map
            • Gets first node
            • Removes the mapping for the specified key from this map
            • Deletes a node
            • Returns the value associated with the specified key
            • Returns true if the map contains the specified key
            • Returns an iterator over the keys in the cache
            Get all kandi verified functions for this library.

            SkipList Key Features

            No Key Features are available at this moment for SkipList.

            SkipList Examples and Code Snippets

            No Code Snippets are available at this moment for SkipList.

            Community Discussions


            why Redis use skiplist to implement zset
            Asked 2021-Apr-02 at 08:36

            I study the implementation of Redis, I know that there are two data structure (skiplist and ziplist) behind zset. I know some basic idea of skiplist (keep multiple pointer to access next element faster, avg time complexity of search is O(logN)).

            My question is :
            I read the info said that there are two situations that Redis will use skiplist to implement zset, first : there are many members in zset, second : memebers in zset are long string.

            What's the benefit to use skiplist instead of ziplist in these two situations, why these two situations need special treatment? Why don't we always use one data structure to implement zset?



            Answered 2021-Apr-02 at 08:36

            ziplist is O(n) time complexity for searching and updating and skiplist is O(logN)

            The only benefit for ziplist is memory usage. As zip list implement by linear memory address and no pointers to other nodes, it can save a lot of memory space for Redis.

            When you only have few members in zset, O(N) and O(logN) will not have significant difference. But memory usage will have huge differences(consider you have 1m keys of zset and each zset only have 10 members).

            And when there are a lot of members in zset(like 1m), time complexity is important since it will affect the concurrent performance.



            in DXL, how to get the handle of a module that I don't open myself in the DXL script
            Asked 2021-Mar-30 at 16:05

            I have a DXL script that open (read or edit) modules and put them in a skip list (so that I could close them at the end)

            The skip list store the module handle of each module read or edit :



            Answered 2021-Mar-30 at 16:05

            Not sure if this is due to the excerpt you posted, but you should always turn off the autodeclare option and ensure that you always use the correct types for your variables by either checking the DXL manual or by using alternative sources like the "undocumented perms list" . data performed on a ModuleVersion returns type Module. So you already have what you need. An alternative would be the perm bool open(ModName_ modRef). And note that the perm module does not return a Module, but a ModName_. Also, in addition to bool isRead(Module m), bool isEdit(Module m) and bool isShare(Module m)(!!) when you really want to close modules that have been opened previously, you might want to check bool unsaved(Module m)



            Is there a elegant implement of the Iterator for the Rc> in Rust?
            Asked 2021-Feb-27 at 15:02

            When I tried to implement the SkipList by rust, I was trapped by the implement of Iterator of Rc>. Code is listed:



            Answered 2021-Feb-27 at 15:02

            Is there a elegant implement of the Iterator for the Rc in Rust?

            Not really. There's two big things in your way.

            One limitation when building an Iterator is that the output type cannot reference the iterator itself. It can either return an owned value (no lifetimes involved) or return references bound to the lifetime of some other object.

            I see you've tried to communicate that you want to return Refs bound to the lifetime of the orignal SkipList by using PhantomData<&'a K> and also using 'a in your Iterator::Item. However, since your iterator can only source values from ptr, an owned value with no lifetime-linkage to 'a, the compiler will complain about mismatched lifetimes at one point or another.

            In order to do this, your iterator would have to use something bound to 'a, probably some form of Option<'a, _>>.

            However, another limitation is when you have nested RefCells, with each level that you iterate, you need to keep around an additional Ref. The reason being that borrows from a Ref don't keep the lifetime of the RefCell, but from the Ref itself.



            remove string with wildcard form list
            Asked 2021-Jan-30 at 18:17

            how can I remove an element from a list if it only contains components. Or how can I bet a wildcard?

            i want remove '+03+ [ NEW INFO WILL RESOLVE TO TILL ]+' in test, wehen 'new' from skiplist match is



            Answered 2021-Jan-30 at 17:40

            wiht list comprehension:



            Skiplist implementation using C
            Asked 2020-Oct-11 at 18:13

            Below is my skiplist implementation, The code working fine, but what I need this that when key matches with the existing key in then value to be updated with the new value, but in my case the item inserted twice and the data is not replaced. I want to implement this at the time of update so that i do not have to search the entire list.

            Any help in this regard is highly appreciated



            Answered 2020-Oct-11 at 18:13
            Updating existing elements

            If you want your code to be able to update existing elements when inserting a new value, then you have to combine the searching you do in containsSkipList() with the creation of a new skipLink. So:



            ConcurrentSkipListSet internal working, difference from TreeSet
            Asked 2020-Aug-23 at 16:52

            Only difference I understand is between iterators. SkipList has weakly consistent, while TreeSet has fail-fast. Other than that I don't see any synchronized methods inside SkipList (although it is in Concurrent package).

            Can someone please explain to me how is SkipList concurrent when it doesn't have any synchronization in it? What problems can it help me with and why should I ever use it other than this difference between Iterators?



            Answered 2020-Aug-23 at 16:52

            …how is SkipList concurrent when it doesn't have any synchronization in it?…

            TL;DRConcurrentSkipListSet is concurrent because the elements it holds cannot be written to at the same time by concurrently executing threads. It achieves its concurrency without using synchronized and locks.

            The long version

            Concurrency in the context of the concurrent collections, does not necessarily mean those classes all implement thread safety using monitors (aka, the synchronized keyword).

            First you should understand that thread safety is essentially about ensuring that two or more competing threads do not modify the shared state of an application. Then you realize that there are ways (some more performant) other than synchronized to achieve thread safety.

            Making sure your state cannot be modified (that it's immutable) in the first place is one simple but very effective way to get thread safety.

            Also, a class can be thread safe by delegating its thread safety responsibilities to a different, thread-safe class.

            ConcurrentSkipListSet is considered to be concurrent because, as its Javadoc says, its: „Insertion, removal, update, and access operations safely execute concurrently by multiple threads“.

            It achieves its concurrency because it delegates its thread safety responsibilities to a thread-safe class; namely: ConcurrentSkipListMap.

            ConcurrentSkipListSet is thread-safe because ConcurrentSkipListMap is. And ConcurrentSkipListMap is thread-safe because, by using AbstractMap.SimpleImmutableEntry internally, it guarantees that none of its state (its keys and values) can be modified by currently executing threads, because its state is immutable.

            You can see ConcurrentSkipListSet delegating to ConcurrentSkipListMap at several places in the source code I linked to above. If you're interested in learning more about delegating thread safety, I recommend you read Chapter 4, Composing Objects, Java Concurrency In Practice.

            …What problems can it help me with

            Using it gets you free thread-safety. The kind that is way more performant — and with way less risk of shooting yourself in the foot — than using synchronized.

            …why should I ever use it other than this difference between Iterators?

            If the state of your application needs to be stored in some collection and that collection will be accessible in any way to concurrently executing threads, then using ConcurrentSkipListSet is a thread-safe option that you have.



            How to specify the type of a function parameter with combined type CustomStringConvertible and RawRepresentable?
            Asked 2020-Mar-27 at 11:04

            I want a generic function that can instantiate object of a few different enum types I have by supplying the enum type and the Int raw-value. These enums are also CustomStringConvertible.

            I tried this:



            Answered 2020-Mar-27 at 11:04

            The issue is that T.RawValue can be something else than Int with your current type constraints. You need to specify that T.RawValue == Int in order to pass your rawValue: Int input parameter to init(rawValue:).



            Skiplist - trying to implement get() and set() methods
            Asked 2020-Mar-13 at 17:46

            So I'm trying to implement a FastDefaultList class which is basically a skiplist that represents an infinite list with indices 0,1,2,3,…,∞. At the start, every value in this list is assigned the default value null. Otherwise, this class behaves just like a List; it has the add(i,x), remove(i), set(i,x), and get(i) that behave just like the same methods in a list. Each of these operations should run in O(log n) time. A lot of my skiplist code comes from:


            I think I have most of it working for the most part but I'm trying to fix my get() and set() methods. Whenever I try to compile the program I get the error:

            error: no suitable method found for add(int,FastDefaultList.Node,int) add(i, node, 0);

            and I'm not sure why. Any help would be appreciated.



            Answered 2020-Mar-13 at 17:37

            Your add function is accepting 2 params



            Cannot get Pyinstaller to create a standalone with Pandas
            Asked 2020-Mar-06 at 09:56

            Of, so my frustration levels have gotten to the point that I must reach out for assistance.

            I have a single file that uses pandas to read a report and do some data manipulation. I have it completed and would like to create a stand alone exe for it.

            Unfortunately, Pandas is not "out of the box" able to be used when you are creating an executable as i get an error stating : ModuleNotFoundErrer: No Module named 'pandas'

            I went online and looked up solutions, and so far I have done ALL OF THIS:

            Edited the EGTReport.spec file:



            Answered 2020-Mar-06 at 09:56

            I guess you have problem with installation of pandas module. Try to run command "pip install pandas" first may be your pandas package is not install. then you can run pyinstaller.

            However you can do additional things like setup settings follow below example:

            Please fill "install_requires" whatever packages you want.



            Find k-th element in skiplist - explanation needed
            Asked 2019-Nov-04 at 16:35

            We're learning about skiplists at my university and we have to find k-th element in the skiplist. I haven't found anything about this in the internet, since skiplist in not really a popular data structure. W. Pugh in his original article wrote:
            Each element x has an index pos(x). We use this value in our invariants but do not store it. The index of the header is zero, the index of the first element is one and so on. Associated with each forward pointer is a measurement, fDistance, of the distance traversed by that pointer:
            x→fDistance[i] = pos(x→forward[i]) – pos(x).
            Note that the distance traversed by a level 1 pointer is always 1, so some storage economy is possible here at the cost of a slight increase in the complexity of the algorithms.



            Answered 2018-May-01 at 20:40

            I'm going to assume you're referring to how to find the k-th smallest (or largest) element in a skip list. This is a rather standard assumption I think, otherwise you have to clarify what you mean.

            I'll refer to the GIF on wikipedia in this answer:

            Let's say you want to find the k = 5 smallest element.

            You start from the highest level (4 in the figure). How many elements would you skip from 30 to NIL? 6 (we also count the 30). That's too much.

            Go down a level. How many skipped from 30 to 50? 2: 30 and 40.

            So we reduced the problem to finding the k = 5 - 2 = 3 smallest element starting at 50 on level 3.

            How many skipped from 50 to NIL? 4, that's one too many.

            Go down a level. How many skipped from 50 to 70? 2. Now find the 3 - 2 = 1 smallest element starting from 70 on level 2.

            How many skipped from 70 to NIL? 2, one too many.

            From 70 to 90 on level 1? 1 (itself). So the answer is 70.

            So you need to store how many nodes are skipped for each node at each level and use that extra information in order to get an efficient solution. That seems to be what fDistance[i] does in your code.


            Community Discussions, Code Snippets contain sources that include Stack Exchange Network


            No vulnerabilities reported

            Install SkipList

            You can download it from GitHub.
            You can use SkipList like any standard Java library. Please include the the jar files in your classpath. You can also use any IDE and you can run and debug the SkipList component as you would do with any other Java program. Best practice is to use a build tool that supports dependency management such as Maven or Gradle. For Maven installation, please refer For Gradle installation, please refer .


            For any new features, suggestions and bugs create an issue on GitHub. If you have any questions check and ask questions on community page Stack Overflow .
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