set

问题 I'm trying to move some of my business logic out of my programs and into stored procedures. I'm really a VB.NET programmer, and not a SQL expert, but I'm learning more SQL and finding that in a lot of cases, it's faster to let SQL do my processing and return small amounts of data rather than giving me a ton of stuff and having my programs chomp through it. So, my current problem is this: I'm creating a timeline of something that has occurred from several different sources in a database. The

问题 Suppose I have the current membership status of a group, i.e. names of members. Additionally, I have data on times when some new member may have been added to the group and / or an old member may have been removed from the group. The task at hand is to recreate the membership of the group at all these points in time. I've looked around but did not find a ready solution for this problem. Does anybody know an elegant method of doing this? Reproducible example: Input: periods <- 5 indx <- paste0

问题 In the following code, the g++ compiler surprisingly cannot decide which operator to use when they are embedded in a struct to serve as a comparator argument in a set: #include <string> #include <set> struct KeyWord { std::string str; int qt; KeyWord(const std::string aKw = "", const int aQt = 0) : str(aKw), qt(aQt) {} }; struct CompareKeywords { bool operator() (const std::string& left, const std::string& right) const { if (left.size() > right.size()) return true; else if (left.size() <

问题 I have an array of image variables that get preloaded using javascript to make an image sequence animation. The issue I have is setting the img element from HTML to use one of these images. It seems all the properies are strings? Here's how I set the array of images in javascript: for(var i = 0; i < 30; i ++){ anim[i] = new Image(); if(i < 10){ anim[i].src = "images/anim/frame0" + i + ".png"; } if(i >= 10){ anim[i].src = "images/anim/frame" + i + ".png"; } } and I simply have an ^img tag =

问题 I have an Object that contains many pieces of information, a Title String, Date String, and NSArray, amongst others. This Object has 8 different sets of this information. I want to find out which Set's Title has the most occurrences of the word "Sunday". After the data loads, I run some calculations: NSArray *yourArrayhere = self.theObject[@"DatesSuggested"]; int occurrences = 0; for(NSString *string in yourArrayhere){ occurrences += ([string isEqualToString:@"Sunday"]?1:0); //certain object

问题 I am trying to write an implementation of Set which has an additional method randomElement() which returns an element at random from the Set . I have based the implementation on HashSet for a fast contains() method. I have also used an ArrayList so that the randomElement() method is O(1) too - with an ArrayList all you have to do is choose a random index. Here is my code. public final class RandomChoiceSet<E> extends AbstractSet<E> { private final List<E> list = new ArrayList<>(); private

问题 It's difficult to explain the case by words, let me give an example: var myObj = { 'name': 'Umut', 'age' : 34 }; var prop = 'name'; var value = 'Onur'; myObj[name] = value; // This does not work eval('myObj.' + name) = value; //Bad coding ;) How can I set a variable property with variable value in a JavaScript object? 回答1: myObj[prop] = value; That should work. You mixed up the name of the variable and its value. But indexing an object with strings to get at its properties works fine in

问题 I have a map that contains values which could exist for multiple keys. So I figured I needed to setup a map like this: Map<Integer, Set<Long>> myMap = new HashMap<Integer, Set<Long>> I would like to retrieve a value from a key's set of values. The problem is that I don't know how to add a long value to the set in myMap and I don't know how to check if myMap contains a value in it's values' set. Is this implementation incorrect? 回答1: You need something like this. if(myMap.containsKey(myKey)){

问题 huge_list parameter is something like [[12,12,14],[43,356,23]] . And my code to convert list to set is: cpdef list_to_set(list huge_list): cdef list ids cdef list final_ids=[] for ids in huge_list: final_ids.append(set(ids)) return final_ids I have 2800 list elements, each has 30,000 id. It takes around 19 second. How to improve performance? EDIT 1: Instead of set I used unique in numpy as below and numpy speeds up by ~7 seconds: df['ids'] = df['ids'].apply(lambda x: numpy.unique(x)) Now it

问题 I'm working on a batch a big batch script, I need to create a menu that show options depending on settings in multiple .ini files, I've got the code to check the ini files down and working without much of a problem but from some reason, when I try to check if a variableX is empty and if so set variableY to 0 (zero), then if variableX not empty set variableY to 1, it doesn't work, I need some help here. For the time being I'm creating the menu in a separate batch file from my full script, so I