tuples

问题 Consider the following bubble sort program: arr = map(int, raw_input().split(' ')) print "Unsorted: \n{arr_name}".format(arr_name = arr) for j in range(len(arr) - 1, 0, -1): for i in range(j): if (arr[i] > arr[i + 1]): arr[i], arr[i + 1] = arr[i +1], arr[i] print "Sorted: \n{arr_name}".format(arr_name = arr) Usually a temp variable is used for sorting and that would be mean a space complexity of 0(1) . But my understanding is that, tuple swap is only a reassignment of identifiers to objects

问题 This question already has answers here : Python - is there a “don't care” symbol for tuple assignments? (9 answers) Closed last month . def get(): ... ... return x,y,z a,b,c = get() i don't need b, c is there a solution to ignore them ( something like don't care ) 回答1: The recommended way of doing this is to use the _ variable name, as indicated by Abdul Niyas P M, this will not store the values captured by the _. x, _, z = 1, 2, 3 # if x and z are necessary # or x, *_ = 1, 2, 3 # if only x

问题 In Python, is it possible to add new methods to built-in classes, such as Tuple. I'd like to add 2 new methods: first() returns the first element of a tuple, and second() returns a new tuple without the first element. So for example: x = (1, 2, 3) x.first() # 1 x.second() # (2, 3) Thanks 回答1: Yes , but don't . There exists a dark and dangerous forbiddenfruit that unsafely and dangerously allows such a thing. But it's a dark place to go. Rather, you can make a new class: class MyTuple(tuple):

问题 In Python, is it possible to add new methods to built-in classes, such as Tuple. I'd like to add 2 new methods: first() returns the first element of a tuple, and second() returns a new tuple without the first element. So for example: x = (1, 2, 3) x.first() # 1 x.second() # (2, 3) Thanks 回答1: Yes , but don't . There exists a dark and dangerous forbiddenfruit that unsafely and dangerously allows such a thing. But it's a dark place to go. Rather, you can make a new class: class MyTuple(tuple):

问题 I want to create a std::vector of std::tuple 's ( std::vector<std::tuple<Ts...>> ) from two std::vector 's by moving the data of the std::vector s. Let's assume I have a struct similar to this (added std::cout s to showcase the problem). template<typename T> struct MyType { constexpr MyType() { std::cout << "default constructor\n"; } constexpr MyType(const T& data) : m_data(data) { std::cout << "data constructor\n"; } constexpr MyType(const MyType& other) : m_data(other.m_data) { std::cout <<

问题 I need to forward the values of a tuple to a member initializer: struct Struct { Member1 member1; Member2 member2; template<typename Tuple1, typename Tuple2> Struct( Tuple1&& tuple1, Tuple2&& tuple2 ) : member1(tuple1...), member2(tuple2...) {} }; The code above obviously isn't valid. How can I express it? Member1 and Member2 have no default/copy/move constructor. I know about std::apply , as suggested in How do I expand a tuple into variadic template function's arguments?. I also know about

问题 I have 2 Lists. First one is Type string . The second is type object . Now I want to get both lists into a Tuple<string,object> . like this var List = new(string list1, object list2)[] How do I do this? I had to create 2 seperate lists, because I am Serializing the object and the serializing wouldn't work if i had a List<Tuple<string,object>> in the first place. Both lists can get big so maybe with foreach loop? 回答1: You can use the Zip method to create one list of the two: var lst = new List

问题 I have a dataframe that has a column of strings as follows: mydata <- c("-1.356670,35.355030", "-1.356670,35.355030", "-1.356620,35.355890", "-1.356930,35.358660", "-1.357000,35.359060" ) df <- data.frame(mydata) I want to convert it into a dataframe containing two columns" long and lat , with each being a numeric type. What is the best way to do this? I've tried using lapply , but cannot seem to make it work. 回答1: With base R you can do: df$Long <- as.numeric(sapply(strsplit(as.character(df

问题 I have a list of List of Tuples (string, float) with float('nan') . How can i get the tuple with the smallest number? If I use min I always get the nan . [('GroundBasedMechWT', nan), ('GroundBasedCTL', nan), ('GroundBasedManualWT', nan), ('GroundBasedManualLog', nan), ('CableManualWTLog', 60.77), ('CableManualWT', 58.52), ('CableManualLog', 68.17), ('CableManualCTL', nan), ('HelicopterManualWT', 96.82), ('HelicopterManualCTL', nan)] 回答1: You could also try this: min(filter(lambda t: not math

问题 I have a list of List of Tuples (string, float) with float('nan') . How can i get the tuple with the smallest number? If I use min I always get the nan . [('GroundBasedMechWT', nan), ('GroundBasedCTL', nan), ('GroundBasedManualWT', nan), ('GroundBasedManualLog', nan), ('CableManualWTLog', 60.77), ('CableManualWT', 58.52), ('CableManualLog', 68.17), ('CableManualCTL', nan), ('HelicopterManualWT', 96.82), ('HelicopterManualCTL', nan)] 回答1: You could also try this: min(filter(lambda t: not math