tuples

问题 Hey, I would like to be able to perform this but with being selective for which lists I sum up. Let's say, that same example, but with only adding up the first number from the 3rd and 4th list. 回答1: Something like: sum(int(tuple_list[i][0]) for i in range(3,5)) range(x, y) generates a list of integers from x(included) to y(excluded) and 1 as the step. If you want to change the range(x, y, step) will do the same but increasing by step. You can find the official documentation here Or you can do

问题 What would be the easiest way to create a list of n-tuples in Python? For example, if I want to create for a number n (for e.g. 3): I'd want to generate the following set of tuples: (1,1,1) (1,1,2) (1,1,3) (2,1,1) (2,1,2) (2,1,3) (3,1,1) (3,1,2) (3,1,3) (1,2,1) (1,2,2) (1,2,3) (2,2,1) (2,2,2) (2,2,3) (3,2,1) (3,2,2) (3,2,3) (1,3,1) (1,3,2) (1,3,3) (2,3,1) (2,3,2) (2,3,3) (3,3,1) (3,3,2) (3,3,3) 回答1: Use itertools.product: >>> from itertools import product >>> list(product(range(1, 4), repeat

问题 What would be the easiest way to create a list of n-tuples in Python? For example, if I want to create for a number n (for e.g. 3): I'd want to generate the following set of tuples: (1,1,1) (1,1,2) (1,1,3) (2,1,1) (2,1,2) (2,1,3) (3,1,1) (3,1,2) (3,1,3) (1,2,1) (1,2,2) (1,2,3) (2,2,1) (2,2,2) (2,2,3) (3,2,1) (3,2,2) (3,2,3) (1,3,1) (1,3,2) (1,3,3) (2,3,1) (2,3,2) (2,3,3) (3,3,1) (3,3,2) (3,3,3) 回答1: Use itertools.product: >>> from itertools import product >>> list(product(range(1, 4), repeat

问题 I've been trying to figure out how to add multiple tuples that contain multiple values to to a single key in a dictionary. But with no success so far. I can add the values to a tuple or list, but I can't figure out how to add a tuple so that the key will now have 2 tuples containing values, as opposed to one tuple with all of them. For instance say the dictionary = {'Key1':(1.000,2.003,3.0029)} and I want to add (2.3232,13.5232,1325.123) so that I end up with: dictionary = {'Key1':((1.000,2

问题 Here's an example of what I'm talking about: typealias SomeTuple = (string: String, int: Int) var tupleArray: [SomeTuple] = [] // Fails // tupleArray.append(string: "Hello", int: 42) // Works let string = "Hello" let num = 42 tupleArray.append(string: string, int: num) // Fails // var varString = "Hi Again" // var varNum = 234 // tupleArray.append(string: varString, int: varNum) Why does the .append(tupleName: val, anotherTupleName: anotherVal) syntax only work when the values are declared

问题 This question already has answers here : How can you iterate over the elements of an std::tuple? (18 answers) Closed 10 months ago . Does anyone know of a good, clean way to iterate over a tuple in C++17 / 20? Let's say we have a bit of code like this: class Test { public: Test( int x ) : x_(x) {}; void Go() const { std::cout << "Hi!" << x_ << "\n" ; } int x_; }; int main() { std::tuple tplb{ Test{1} , Test{2} , Test{3} }; } How could we iterate through the tuple and call the Go() method on

问题 I am writing a data structure (basically a hashmap) in Scala that will take one tuple (of possibly different number of arguments each time) and do something with it. To generically implement this, I defined a type: type T <: Tuple1[_] with Tuple2[_,_] with Tuple3[_,_,_] with Tuple4[_,_,_,_] with Tuple5[_,_,_,_,_] and then the data structure val map = new HashMap[Int, T] But this is ugly, since I have to change the type every time I have to handle more arguments in a tuple. Is there to define

问题 I have a struct with members x,y,z and w. How do I sort efficiently first by x, then by y, by z and finally by w in C++? 回答1: If you want to implement a lexicographical ordering, then the simplest way is to use std::tie to implement a less-than or greater-than comparison operator or functor, and then use std::sort on a collection of your structs. struct Foo { T x, y, z, w; }; .... #include <tuple> // for std::tie bool operator<(const Foo& lhs, const Foo& rhs) { // assumes there is a bool

问题 I've been trying to create a function with a tuple-list as an argument but I keep getting the error: "unresolved flex record (need to know the names of ALL the fields in this context)" My code is: fun convert d = ( (map (#1) d) , (map (#2) d) ); This is basicaly trying to convert a list of pairs into a pair of lists.I've also tried to declare the type of d as :('a * 'b) list but that resulted in even more errors. I assume that this has something to do with the unknown size of the tupple and

问题 I don't understand why the following case doesn't match. Null should be an instance of Any, but it doesn't match. Can someone explain what is going on? val x = (2, null) x match { case (i:Int, v:Any) => println("got tuple %s: %s".format(i, v)) case _ => println("catch all") } prints catch all Thanks. 回答1: This is exactly as specified. Type patterns consist of types, type variables, and wildcards. A type pattern T is of one of the following forms: * A reference to a class C, p.C, or T#C. This