hashtable

问题 Say I had a list of tuples: [(98, 'studentA'), (97, 'studentB'), (98, 'studentC'), (95,'studentD')] And I wanted to organize it so that the students are grouped together by the first number in the tuple, what would be the best approach? I was thinking about creating an array of lists, in which each index of the array would be a different score (98, 97, and 95 in this example) and the students would be in the list at that index. For a much larger dataset I was considering creating a chaining

问题 Java code: //BleDevice is a class public Hashtable<String, BleDevice> meusBLEs = new Hashtable<String, BleDevice>(); //BleRequest is another class BleRequest currentRequest = null; //deviceAddress is a string from BleRequest BleDevice ble=meusBLEs.get(currentRequest.deviceAddress); I'm using a hashtable and set the value to the BleDevice variable; Now what I'm trying to do in c#, is the same thing but using Dictionary: public Dictionary<String, BleDevice> meusBLEs = new Dictionary<String,

问题 I would like to know if I can use Hash table as a return type of a function in C++. :) 回答1: The C++ standard library implementation of a hash table is std::unordered_map and yes, you can happily return it from a function: std::unordered_map<X, Y> foo() { std::unordered_map<X, Y> map; return map; } It can be copied because it has a copy constructor † . If you implement your own hash table, it will also be returnable if it has a copy constructor. † In C++11, a move constructor will be

问题 what i am trying to implement is to write an R hashtable to a csv file excel ( column like formatted file- keys in first column and values in the second). please consider this example. (the hash table is created by hash package) <hash> containing 5 key-value pair(s). 1 : 4 2 : NULL 3 : NULL 4 : 3 1 5 : 1 4 when I simply use this write.csv(hash, file = "hash.csv",row.names=FALSE) it gives me this error Error in as.data.frame.default(x[[i]], optional = TRUE) : cannot coerce class "structure(

问题 Assuming that I have a hashtable: $tokens = @{ Id=9999; Title="Lorem ipsum dolor sit amet"; Author=@{Name="John Doe"; Email='john.doe@foo.xyz'}; Analyst=@{Name="Jane Doe"; Email='jane.doe@foo.xyz'} } And a template that I would like to populate, replacing the tokens (e.g. __Title__ ) with the corresponding hashtable's value: /* Author: __Author.Name__ <__Author.Email__> Analyst: __Analyst.Name__ <__Analyst.Email__> Request: __Title__ [__Id__] */ ... Should become: /* Author: John Doe <john

问题 I have built custom Rules Engine, where each element of this engine is a descendant of DependencyObject class, so that it could be described in XAML including support for dependency properties, markup extensions, bindings, and so on. The purpose of this Rules Engine is to process certain information which comes as an input and to return the output information back to the queue. The entire tree of object is being instantiated once (from XAML) in a single thread and the series of Input objects

问题 I'm grabbing data from a SQL Server database into a DataTable that I convert using AsEnumerable and then separating using a series of Linq statements. My ultimate goal is to take those Linq queries and have it generate a HashTable for me. So instead of Anonymous types: var facebookPosts = from f in results.AsEnumerable() where f.GetInt("SocialMediaTypeID").Equals( (int) SocialMediaRecordType.FacebookPost) select new { Headline = f.GetString("Headline"), Parameters = new Parameters(f.GetString

问题 I have one problem and I think there is not much to correct to work right. I have table (with desired output column 'sum_usage'): id opt t_purchase t_spent bonus usage sum_usage a 1 10NOV2017:12:02:00 10NOV2017:14:05:00 100 9 15 a 1 10NOV2017:12:02:00 10NOV2017:15:07:33 100 0 15 a 1 10NOV2017:12:02:00 10NOV2017:13:24:50 100 6 6 b 1 10NOV2017:13:54:00 10NOV2017:14:02:58 100 3 10 a 1 10NOV2017:12:02:00 10NOV2017:20:22:07 100 12 27 b 1 10NOV2017:13:54:00 10NOV2017:13:57:12 100 7 . 7 So, I need

问题 Usually (as in C++), the hash function returns any size_t value -- thus many different hash values are possible (2^32). That is why I always thought that when people talked about them being implemented as tables, that is not really true in practice because the table would be much too big (2^32 entries). Of course my assumption was wrong that the table must be as big as the full range of hash values. It seems that the actual implementation is more difficult than I thought. What I always had in

问题 After looking at a simple hash table implementation in JavaScript, the key index is computed as: function index(str, max) { var hash = 0; for (var i = 0; i < str.length; i++) { var letter = str[i]; hash = (hash << 5) + letter.charCodeAt(0); hash = (hash & hash) % max; } return hash; } So I'm wondering in the case of v8, how it uses a function similar to that but makes sure the index is unique on the object. So if you do this: { a: 'foo', b: 'bar' } Then it becomes something like: var i =