multimap

问题 I am reading from a huge csv file which contains duplicate entries. I was able to read the whole csv file into a Multimap . I am also able to obtain the keyset with duplicate values and write them to a file. I want to get the value associated with each of the keys and write it to a file but unable to do so. I cant seem to find any of the options that might help me. I tried using entries() method which according to the doc Returns a view collection of all key-value pairs contained in this

问题 Imagine a multimap tracking persons, each of whom has a list of assigned tasks. Map< Person , List< Task > > personToTasks = Map.of( new Person( "Alice" ) , List.of( new Task( "a1" ), new Task( "a2") ) , new Person( "Bob" ) , List.of( new Task( "b1" ) ) , new Person( "Carol" ) , List.of( new Task( "c1" ), new Task( "c2"), new Task( "c3") ) ) ; How can I use streams to get a new map, mapping each Person to an Integer with the count of items found in their list of assigned tasks? How to get a

问题 Imagine a multimap tracking persons, each of whom has a list of assigned tasks. Map< Person , List< Task > > personToTasks = Map.of( new Person( "Alice" ) , List.of( new Task( "a1" ), new Task( "a2") ) , new Person( "Bob" ) , List.of( new Task( "b1" ) ) , new Person( "Carol" ) , List.of( new Task( "c1" ), new Task( "c2"), new Task( "c3") ) ) ; How can I use streams to get a new map, mapping each Person to an Integer with the count of items found in their list of assigned tasks? How to get a

问题 My controller can't map a Google Guava Multimap coming from the frontend. I send from my Javascript this object: {1:[true,false], 2:[false,true], ...}. If I use a standard java.util.Map<Long, List<Boolean>> everything works fine. But not with the Guava Multimap . Do I have to configure Spring to use some custom converter, or what is the problem? The controller is: @RequestMapping(path = "/myurl", method = RequestMethod.POST, produces = CotrollerKonstanten.JSON_UTF8) public long myMethod(

问题 Given a map such as this where we have a frequency count per day-of-week for a year: Map.of( DayOfWeek.MONDAY , 52 , DayOfWeek.TUESDAY , 52 , DayOfWeek.WEDNESDAY, 53 , DayOfWeek.THURSDAY , 53 , DayOfWeek.FRIDAY , 52 , DayOfWeek.SATURDAY , 52 , DayOfWeek.SUNDAY , 52 ) …or as text: {MONDAY=52, TUESDAY=52, WEDNESDAY=53, THURSDAY=53, FRIDAY=52, SATURDAY=52, SUNDAY=52} …how can I invert to produce a multimap of distinct numbers each leading to a collection (list? set?) of the DayOfWeek which owned

问题 Given a map such as this where we have a frequency count per day-of-week for a year: Map.of( DayOfWeek.MONDAY , 52 , DayOfWeek.TUESDAY , 52 , DayOfWeek.WEDNESDAY, 53 , DayOfWeek.THURSDAY , 53 , DayOfWeek.FRIDAY , 52 , DayOfWeek.SATURDAY , 52 , DayOfWeek.SUNDAY , 52 ) …or as text: {MONDAY=52, TUESDAY=52, WEDNESDAY=53, THURSDAY=53, FRIDAY=52, SATURDAY=52, SUNDAY=52} …how can I invert to produce a multimap of distinct numbers each leading to a collection (list? set?) of the DayOfWeek which owned

来源： https://stackoverflow.com/questions/61336175/how-can-i-optimize-my-soft-normal-calculation-function

来源： https://stackoverflow.com/questions/61336175/how-can-i-optimize-my-soft-normal-calculation-function

问题 The built in maps and sets in C++ libraries (including unordered_map and multimap) requires that the find function (used to lookup a specific element) utilize an iterator for traversing the elements. The C++ reference site claims that looking up elements using these data structures takes on average constant time, much like a regular hash table. But wouldn't an iterator have to traverse the entire list, making this O(n) time on average, before finding the element? 回答1: You statement are no

问题 I am given two files one with the name of person and the location that they are from (Evan Lloyd|Brownsville) and one with the name and salary (Evan Lloyd|58697) (the line number that you find the employee on in the first file is not necessarily the line number that find the employee on in the second). The user inputs a location (whole or part). For example if they input "ville" or "Ville" it should include all of the employees in Brownsville, Clarksville, Greenville, etc. I am supposed to