sortedmap

Find element position in a Java TreeMap

由 喜夏-厌秋 提交于 2019-12-05 12:57:22
问题 I am working with a TreeMap of Strings TreeMap<String, String> , and using it to implement a Dictionay of words. I then have a collection of files, and would like to create a representation of each file in the vector space (space of words) defined by the dictionary. Each file should have a vector representing it with following properties: vector should have same size as dictionary for each word contained in the file the vector should have a 1 in the position corresponding to the word position

Java. Sorted map by value [duplicate]

由 谁说胖子不能爱 提交于 2019-12-04 03:31:38
问题 This question already has answers here : Closed 7 years ago . Possible Duplicate: How to sort a Map<Key, Value> on the values in Java? I need sorted map like TreeMap but sorted by value. My map will be huge, so i can't just sort my map anytime i need. Exist any good solution to resolve this problem? Maybe exist external jar who meets this? 回答1: There are a number of ways to satisfy your requirement. As you have subsequently clarified that you may have duplicate objects in your current TreeMap

Why Java 6 overrides keySet(), entrySet() and values() interface in SortedMap

由 一个人想着一个人 提交于 2019-12-02 03:53:13
问题 Java 5 http://docs.oracle.com/javase/1.5.0/docs/api/java/util/SortedMap.html Java 6 https://docs.oracle.com/javase/6/docs/api/java/util/SortedMap.html As you can see that since Java 6, these three apis are overridden. Can anyone tell me what's the purpose of making such a change? 回答1: The methods had to be overridden in order to have their own Javadoc. Other reasons why you would declare a method in a subinterface are the ability to restrict the return type or to add annotations, but they

Java. Sorted map by value [duplicate]

由 不羁岁月 提交于 2019-12-01 18:14:58
Possible Duplicate: How to sort a Map<Key, Value> on the values in Java? I need sorted map like TreeMap but sorted by value. My map will be huge, so i can't just sort my map anytime i need. Exist any good solution to resolve this problem? Maybe exist external jar who meets this? There are a number of ways to satisfy your requirement. As you have subsequently clarified that you may have duplicate objects in your current TreeMap , perhaps you could replace your TreeMap with a third-party multimap ( Guava , Apache Commons Collections ), then swap your keys and values around - i.e. replace TreeMap

Java “cannot cast to Comparable” when using TreeMap [duplicate]

由 给你一囗甜甜゛ 提交于 2019-11-29 10:05:50
Possible Duplicate: Java: SortedMap, TreeMap, Comparable? How to use? I am using the Java JungI graph package and Netbeans 7. I am getting the following error from Java: Exception in thread "main" java.lang.ClassCastException: graphvisualization.MyVertex cannot be cast to java.lang.Comparable at java.util.TreeMap.put(TreeMap.java:542) Here is the code associated with the error: SortedMap<MyVertex, Double> vMap = new TreeMap<MyVertex, Double>(); double curRank = 0; for(MyVertex v: g.getVertices()) //g is a SparseGraph<MyVertex, MyEdge> { curRank = vertexRank.getVertexScore(v); vMap.put(v,

Why are there no sorted containers in Python's standard libraries?

由 偶尔善良 提交于 2019-11-28 06:07:55
Is there a Python design decision (PEP) that precludes a sorted container from being added to Python? ( OrderedDict is not a sorted container since it is ordered by insertion order.) It's a conscious design decision on Guido's part (he was even somewhat reluctant regarding the addition of the collections module). His goal is to preserve "one obvious way to do it" when it comes to the selection of data types for applications. The basic concept is that if a user is sophisticated enough to realise that the builtin types aren't the right solution for their problem, then they're also up to the task

Java: SortedMap, TreeMap, Comparable? How to use?

由 こ雲淡風輕ζ 提交于 2019-11-27 22:33:22
I have a list of objects I need to sort according to properties of one of their fields. I've heard that SortedMap and Comparators are the best way to do this. Do I implement Comparable with the class I'm sorting, or do I create a new class? How do I instantiate the SortedMap and pass in the Comparator? How does the sorting work? Will it automatically sort everything as new objects are inserted? EDIT: This code is giving me an error: private TreeMap<Ktr> collection = new TreeMap<Ktr>(); (Ktr implements Comparator<Ktr> ). Eclipse says it is expecting something like TreeMap<K, V> , so the number

How to initialize a TreeMap with pre-sorted data?

由 点点圈 提交于 2019-11-27 06:15:25
问题 My app uses a TreeMap to keep data sorted and have log(n) lookups & inserts. This works great in the general case while the app is running, but when the app first starts, I need to initialize the TreeMap with several million longs that I get in sorted order (ascending). Since these initialization values are already sorted, is there any way to insert them into the TreeMap without paying the log(n) cost of tree insertion and re-balancing? 回答1: Sure! The TreeMap.putAll method (and the TreeMap

Why are there no sorted containers in Python's standard libraries?

由 蹲街弑〆低调 提交于 2019-11-27 00:59:29
问题 Is there a Python design decision (PEP) that precludes a sorted container from being added to Python? ( OrderedDict is not a sorted container since it is ordered by insertion order.) 回答1: It's a conscious design decision on Guido's part (he was even somewhat reluctant regarding the addition of the collections module). His goal is to preserve "one obvious way to do it" when it comes to the selection of data types for applications. The basic concept is that if a user is sophisticated enough to

Java TreeMap Comparator

由 大城市里の小女人 提交于 2019-11-26 17:43:22
I need a comparator for a TreeMap. Should I write this anonymously in the constructor for my TreeMap? How else could I write my comparator. Currently, Java does not like my code (can I do this anonymously?): SortedMap<String, Double> myMap = new TreeMap<String, Double>(new Comparator<Entry<String, Double>>() { public int compare(Entry<String, Double> o1, Entry<String, Double> o2) { return o1.getValue().compareTo(o2.getValue()); } }); Can I do the above anonymously? How else could I do this? I want to sort myMap by the Value not the Key You can not sort TreeMap on values. A Red-Black tree based
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