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    Interval Tree

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    The package @flatten-js/interval-tree is an implementation of interval binary search tree according to Cormen et al. Introduction to Algorithms (2009, Section 14.3: Interval trees, pp. 348–354). Cormen shows that insertion, deletion of nodes and range queries take O(log(n)) time where n is the number of items stored in the tree.

    This package is a part of flatten-js library.

    An earlier implementation, in package flatten-interval-tree, is no longer supported and will be deprecated soon. Please use this package (@flatten-js/interval-tree) instead.


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    npm install --save @flatten-js/interval-tree


    import IntervalTree from '@flatten-js/interval-tree'


    Tree stores pairs <key,value> where key is an interval, and value is an object of any type. If value omitted, tree stores only keys.

    In a <key,value> tree none of the value can be undefined.

    Interval can be simply a pair of numbers or it can be a user-defined object that implements IntervalInterface described in typescript declaration file index.d.ts.

    Axis aligned rectangle is an example of such interval. We may look at rectangle as an interval between its low left and top right corners. See Box class in flatten-js library as an example of IntervalInterface implementation.


    let tree = new IntervalTree();
    let intervals = [[6,8],[1,4],[5,12],[1,1],[5,7]];
    // Insert interval as a key and string "val0", "val1" etc. as a value 
    for (let i=0; i < intervals.length; i++) {
    // Get array of keys sorted in ascendant order
    let sorted_intervals = tree.keys;              //  expected array [[1,1],[1,4],[5,7],[5,12],[6,8]]
    // Search items which keys intersect with given interval, and return array of values
    let values_in_range =[2,3]);     //  expected array ['val1']


    Create new instance of interval tree

    let tree = new IntervalTree()

    Insert(key[, value])

    Insert new item into the tree. Key is an interval object or pair of numbers [low, high].
    Value may represent any value or reference to any object. If value omitted, tree will store and retrieve keys as values.
    Method returns reference to the inserted node

    let node = tree.insert(key, value)


    Method returns true if item {key, value} exists in the tree.
    Method may be useful if need to support unique items.

    let exist = tree.exist(key, value)

    Remove(key, value)

    Removes item from the tree. Returns true if item was actually deleted, false if not found

    let removed = tree.remove(key, value)

    Search(interval[, outputMapperFn])

    Returns array of values which keys intersected with given interval.

    let resp =

    Optional outputMapperFn(value, key) enables to map search results into custom defined output. Example:

    const composers = [
        {name: "Ludwig van Beethoven", period: [1770, 1827]},
        {name: "Johann Sebastian Bach", period: [1685, 1750]},
        {name: "Wolfgang Amadeus Mozart", period: [1756, 1791]},
        {name: "Johannes Brahms", period: [1833, 1897]},
        {name: "Richard Wagner", period: [1813, 1883]},
        {name: "Claude Debussy", period: [1862, 1918]},
        {name: "Pyotr Ilyich Tchaikovsky", period: [1840, 1893]},
        {name: "Frédéric Chopin", period: [1810, 1849]},
        {name: "Joseph Haydn", period: [1732, 1809]},
        {name: "Antonio Vivaldi", period: [1678, 1741]}
    const tree = new IntervalTree();
    for (let composer of composers)
    // Great composers who lived in 17th century
    const searchRes = [1600,1700],
        (name, period) => {return `${name} (${period.low}-${period.high})`});
    // expected to be 
    // [ 'Antonio Vivaldi (1678-1741)', 'Johann Sebastian Bach (1685-1750)' ]


    Returns true if intersection between given and any interval stored in the tree found

    let found = tree.intersect_any(interval)


    Returns number of items stored in the tree (getter)

    let size = tree.size


    Returns tree keys in ascendant order (getter)

    let keys = tree.keys


    Returns tree values in ascendant keys order (getter)

    let values = tree.values


    Returns items in ascendant keys order (getter)

    let items = tree.items


    Enables to traverse the whole tree and perform operation for each item

    tree.forEach( (key, value) => console.log(value) )


    Creates new tree with same keys using callback to transform (key,value) to a new value

    let tree1 =, key) => (key.high-key.low))


    Documentation may be found here:


    npm test


    In lieu of a formal style guide, take care to maintain the existing coding style. Add unit tests for any new or changed functionality. Lint and test your code.




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