any

问题 I am comparing the performance of the any() built-in function with the actual implementation the docs suggest: I am looking for an element greater than 0 in the following list: lst = [0 for _ in range(1000000)] + [1] This is the supposedly equivalent function: def gt_0(lst): for elm in lst: if elm > 0: return True return False And these are the results of the performance tests: >> %timeit any(elm > 0 for elm in lst) >> 10 loops, best of 3: 35.9 ms per loop >> %timeit gt_0(lst) >> 100 loops,

问题 I am not sure if being in linux makes any different, but i have found online that this: cout << "Press Enter to Continue..."; cin.ignore(numeric_limits<streamsize>::max(),'\n'); Should be sufficient, with #include<limits> in the header of course. However, it does not seem to work in my program. It compiles, it runs, but it does not wait. Basically, i have a menu, which lead to a method call to display a list of people on the screen. I wish to pause that list before the system goes back to the

问题 I am using Entity Framework and I need to check if a product with name = "xyz" exists ... I think I can use Any(), Exists() or First(). Which one is the best option for this kind of situation? Which one has the best performance? Thank You, Miguel 回答1: Any translates into "Exists" at the database level. First translates into Select Top 1 ... Between these, Exists will out perform First because the actual object doesn't need to be fetched, only a Boolean result value. At least you didn't ask

问题 I am using Entity Framework and I need to check if a product with name = "xyz" exists ... I think I can use Any(), Exists() or First(). Which one is the best option for this kind of situation? Which one has the best performance? Thank You, Miguel 回答1: Any translates into "Exists" at the database level. First translates into Select Top 1 ... Between these, Exists will out perform First because the actual object doesn't need to be fetched, only a Boolean result value. At least you didn't ask

问题 Hi SQLAlchemy experts out there, here's a tricky one for you: I'm trying to write a query that resolves into something like: SELECT * FROM MyTable where my_column LIKE ANY (array['a%', 'b%']) using SQLAlchemy: foo = ['a%', 'b%'] # this works, but is dirty and silly DBSession().query(MyTable).filter("my_column LIKE ANY (array[" + ", ".join(["'" + f + "'" for f in token.tree_filters]) + "])") # something like this should work (according to documentation), but doesn't (throws "AttributeError:

问题 I have tried both 1) smthng = any (select id from exmplTable) 2) smthng in (select id from exmplTable) and I am getting the same results for my data. Is there any difference for the two expresions ? 回答1: No, in these variants are same: You can see - the execution plans are same too: postgres=# explain select * from foo1 where id in (select id from foo2); ┌──────────────────────────────────────────────────────────────────┐ │ QUERY PLAN │ ╞═══════════════════════════════════════════════════════

问题 When I set c to a var a: [Any] var c: Array<PostCategory> error shown: cannot convert value of type 'Array' to expected argument type [Any] how to solve the problem? 回答1: The error message is a bit misleading but try initializing the array before assigning it: var c: Array<PostCategory> = [] ...or... var c = Array<PostCategory>() 回答2: I bet your PostCategory is a struct . Apparently struct arrays aren't convertible to an Any array. This is weird because all types conforms to the Any protocol.

问题 lst = ['a', 'b', 'c', 'aa', 'bb', 'cc'] def findexact(lst): i=0 key = ['a','g','t'] while i < len(lst): if any(item in lst[i] for item in key): print lst[i] i+=1 findexact(lst) in the above code, the result comes out to be: 'a' 'aa' I would like the result to be: 'a' What is the right way to use any() to get the right result? 回答1: To match your expected output, you cannot use set.intersection as sets are unordered so if you get a as the first item it is totally by chance , you should make key

问题 I have a class RBase, and a RInt class that inherits from it. The Base has three interface functions. As the subclasses that inherit can use different type of values, the function parameter is typed as Any. As a result, I need to use asInstanceOf to implement the subclasses. This is an example. abstract class RBase(val name:String) { def encode(value:Any) : Array[Byte] def decode(byteArray: Array[Byte]) : Any def check(value:Any) : Boolean } class RInt extends RBase("int") { override def

问题 I would like std::map<string, any> *var1 to point to the same memory address/value as std::any *var2 because I know that var2 is pointing to a map<string, any> . The following seems to work: std::map<string, any> *var1 = any_cast<std::map<string, any>>(var2); Is it ok? The problem is that it does not signal bad cast even if var2 is actually not an std::map<string, any>* but something else, but if it is it still works. Am I doing it right? std::map<string, any> *mapptr; std::any realmap = std: