tuples

问题 For example, I have a convert template (any existing library to do it?) template<class T> struct Convert; template<> struct Convert<T0> {typedef C0 Type;}; template<> struct Convert<T1> {typedef C1 Type;}; template<> struct Convert<T2> {typedef C2 Type;}; From the convert, It convert std::tuple<T0, T1, T2>; // version A To std::tuple<C0, C1, C2>; // version B Any way to do it generally, like template<class tupleA, template<class> class Convert> { typedef .... tupleB; } Some other questions:

问题 namespace details { template <std::size_t I = 0, typename Tuple, typename Function, typename... Args> typename std::enable_if<I == std::tuple_size<Tuple>::value, void>::type ForEach(Tuple &t, Function f, Args &... args) {} template <std::size_t I = 0, typename Tuple, typename Function, typename... Args> typename std::enable_if<(I < std::tuple_size<Tuple>::value), void>::type ForEach(Tuple &t, Function f, Args &... args) { f(std::get<I>(t), args...); ForEach<I + 1>(t, f, args...); } } An

问题 This question already has answers here : Flattening a shallow list in Python [duplicate] (23 answers) How to make a flat list out of list of lists? (46 answers) Closed 5 years ago . How can I loop through all the elements in a list of tuples, into an empty list? For example: tup_Before = [(69592, 69582), (69582, 69518), (69518, 69532), (69532, 69525)] tup_After = [69592, 69582, 69582, 69518, 69518, 69532, 69532, 69525] 回答1: A list comprehension: tup_after = [v for t in tup_Before for v in t]

问题 I have the following challenge that I need to create unique object tuples out of object lists. The speical challenge is here how I can do it for dynamic list sizes (n-dimension)? It is easy in case you have a fixed dimension. I hope somebody knows a third party API or has some hints for me how I can reach this. The exampel below shows it for a 3 lists, so it is easier to explain. I have the objects sorted by its class in a list e.g. lista = {a1,a2} listb = {b1,b2,b3} listc = {c1,c2} I like to

问题 I have public static class GlobalVariables { public static List<Tuple<string, string, int>> PopFile; } and I'm trying to use PopFile as a datasource to listbox listBox1.DataSource = GlobalVariables.PopFile; The problem is that it obviously adds ([string], [string], [int]) to the listbox but I want to add only the first items of tuples. Is that possible? I could use foreach (Tuple<string, string, int> i in GlobalVariables.PopFile) { listBox1.Items.Add(i.Item1); } but I'd prefer .DataSource.

问题 I have a text file called CustomerList.txt and it looks like this 134998,Madison,Foxwell,825 John Street,Staunton,VA,24401,6655414998 The end result should be like this with open("CustomerList.txt", "r") as fin: ID, Firstname, Lastname, Address, City, State, Zip, Phone = zip(*[l.split() for l in fin.readlines()]) That's what I have so far, but I get an error that says I need more than 3 values to upack. I just started using tuples yesterday so please keep things as basic as possible for this

问题 I'm starting out in python and thought it'd be a good exercise to try to build a function that determines whether an input passed to it is an integer, and if so whether it's positive. At a later stage I plan to reference that function from within a mathematical function that only accepts positive integers. Anyway, this is the function I built: def is_ok(x): #checks if x is a positive integer is_int = False is_pos = False if type(x) == int: is_int = True # if it's an integer, continue to test

问题 D = [(01294135018, "hello", 500)] def pop(key, D, hasher = hash): try: for item in D: if key in item: return item[2] D.remove(item) print(D) #Just to check if it has been removed except KeyError: pass where key is the users choice, D is the list of tuples, and hasher is just equal to hash. e.g pop("hello", D, hash), should remove the tuple from D, for example a tuple is currently a (hash(key), key, value) so say there is a tuple in D (hash key value is random), for item in D, if the key in

问题 Can someone explain what's going on here? Output from GCC 5.2: #include <iostream> #include <tuple> #include <string> #include <typeinfo> template <typename... Args> void foo (Args&&... args) { std::tuple<Args...> t = std::tie(args...); std::cout << std::is_same<int, std::tuple_element_t<0, decltype(t)>>::value << '\n'; // true std::cout << std::is_same<std::string, std::tuple_element_t<1, decltype(t)>>::value << '\n'; // false std::cout << typeid(std::tuple_element_t<1, decltype(t)>).name()

问题 I have a text file with following content. //((number,(number,date)),number) ((210,(18,2015/06/28)),57.0) ((92,(60,2015/06/16)),102.89777479000209) ((46,(18,2015/06/17)),52.8940162267246) ((204,(27,2015/06/06)),75.2807019793683) I wish to convert it to tuple and need a fast way to do it. As the list of such string's I have is substantially huge. EDIT : I would also, like to maintain the type and structure information. Any help would be appreciated. 回答1: I find scala-parser-combinators is the