map-function

问题 Here is the loop I am trying to use the map function on: volume_ids = [1,2,3,4,5] ip = '172.12.13.122' for volume_id in volume_ids: my_function(volume_id, ip=ip) Is there a way I can do this? It would be trivial if it weren't for the ip parameter, but I'm not sure how to deal with that. 回答1: Use functools.partial(): from functools import partial mapfunc = partial(my_function, ip=ip) map(mapfunc, volume_ids) partial() creates a new callable, that'll apply any arguments (including keyword

问题 Given a dictionary { k1: v1, k2: v2 ... } I want to get { k1: f(v1), k2: f(v2) ... } provided I pass a function f . Is there any such built in function? Or do I have to do dict([(k, f(v)) for (k, v) in my_dictionary.iteritems()]) Ideally I would just write my_dictionary.map_values(f) or my_dictionary.mutate_values_with(f) That is, it doesn't matter to me if the original dictionary is mutated or a copy is created. 回答1: There is no such function; the easiest way to do this is to use a dict

问题 In terms of performance in Python, is a list-comprehension, or functions like map(), filter() and reduce() faster than a for loop? Why, technically, they "run in a C speed", while "the for loop runs in the python virtual machine speed"?. Suppose that in a game that I'm developing I need to draw complex and huge maps using for loops. This question would be definitely relevant, for if a list-comprehension, for example, is indeed faster, it would be a much better option in order to avoid lags

问题 I'm totally new to Scheme and I am trying to implement my own map function . I've tried to find it online, however all the questions I encountered were about some complex versions of map function (such as mapping functions that take two lists as an input). The best answer I've managed to find is here: (For-each and map in Scheme). Here is the code from this question: (define (map func lst) (let recur ((rest lst)) (if (null? rest) '() (cons (func (car rest)) (recur (cdr rest)))))) It doesn't

问题 Is there a way to write an implementation of the Haskell map function using list implementation? I keep getting an error and I do not think I am on the right track. This is what I have: map' :: (a -> b) -> [a] -> [b] map' _ [] = [] map' xs ys = [ (x, y) | x <- xs | y <- ys ] Any help or link that will guide me in the right direction would be much appreciated. 回答1: I believe you mean "comprehension", instead of "implementation". Either way, this would work: map' f as = [f a | a <- as] map' (*

问题 I am new to Javascript. Now, Here I have an array which has multiple objects. So, I want to iterate it and if any of the object matches the condition then I want to return a value and stop that loop. My array of obj is like, var obj = [ { type: "", numberOfQuestions:"", technology:"" }, { type: "1", numberOfQuestions:"4", technology:"abcd" }, { type: "", numberOfQuestions:"6", technology:"ass" } ] And my condition is, validateData(data) { data.High.map((object) => { if((object.type === "") ||

问题 As you can see in the example below, map function in Scheme is variadic function. > (map (lambda (number1 number2) (+ number1 number2)) '(1 2 3 4) '(10 100 1000 10000)) '(11 102 1003 10004) I want to implement this variadic option, but I only succeeded to find the two arguments map implementation: (define (map f lst) (if (null? lst) '() (cons (f (car lst)) (map f (cdr lst))))) Can someone help me implement variadic map function? 回答1: In Scheme, you can write a variadic function as (lambda x .

问题 Does map() iterate through the list like "for" would? Is there a value in using map vs for? If so, right now my code looks like this: for item in items: item.my_func() If it makes sense, I would like to make it map(). Is that possible? What is an example like? 回答1: You could use map instead of the for loop you've shown, but since you do not appear to use the result of item.my_func() , this is not recommended . map should be used if you want to apply a function without side-effects to all

问题 Let's assume there is a list a = [1, 3, 5, 6, 8] . I want to apply some transformation on that list and I want to avoid doing it sequentially, so something like map(someTransformationFunction, a) would normally do the trick, but what if the transformation needs to have knowledge of the index of each object? For example let's say that each element must be multiplied by its position. So the list should be transformed to a = [0, 3, 10, 18, 32] . Is there a way to do that? 回答1: Use the enumerate(

问题 I have a recursive definition of sieve in Haskell for prime number computation. But I don’t know how to write the same function using higher–order functions such as map or filter . Can anybody show me please? sieve [] = [] sieve (x:xs) = check (x:xs) check [] = [] check (x:xs) |x/=2 && x/=3 && x/=5 && x/=7 = comp (x:xs) |otherwise = x : sieve xs comp [] = [] comp (x:xs) |x `mod` 2 == 0 = sieve xs |x `mod` 3 == 0 = sieve xs |x `mod` 5 == 0 = sieve xs |x `mod` 7 == 0 = sieve xs |otherwise = x :