map-function

来源： https://stackoverflow.com/questions/63677178/sicp-ex2-41-map-and-flatmap

来源： https://stackoverflow.com/questions/63677178/sicp-ex2-41-map-and-flatmap

问题 I am making a react-native app that has a custom view like a grid view. All the cells of the view have same size except one. I want to give condition for the cell to have double the size from others. I am making the view through an array using map function. Map function is not taking if statement. How should I use it? // Buttons Array buttons = [['1', '2', '3'], ['a', 'b', 'c'], ['q', 'w', 'e'], ['+', '-', '*'], ] // '-' has double size... import React, { Component } from 'react'; import {

问题 I know, that map(function, arguments) is equivalent to for argument in arguments: function(argument) Is it possible to use map function to do the following? for arg, kwargs in arguments: function(arg, **kwargs) 回答1: You can with a lambda: map(lambda a: function(a[0], **a[1]), arguments) or you could use a generator expression or list comprehension, depending on what you want: (function(a, **k) for a, k in arguments) [function(a, **k) for a, k in arguments] In Python 2, map() returns a list

问题 I know, that map(function, arguments) is equivalent to for argument in arguments: function(argument) Is it possible to use map function to do the following? for arg, kwargs in arguments: function(arg, **kwargs) 回答1: You can with a lambda: map(lambda a: function(a[0], **a[1]), arguments) or you could use a generator expression or list comprehension, depending on what you want: (function(a, **k) for a, k in arguments) [function(a, **k) for a, k in arguments] In Python 2, map() returns a list

问题 I have a function: mapAtOriginal :: (a -> a) -> [Int] -> [a] -> [a] mapAtOriginal f is xs = helper 0 is xs where helper _ [] xs = xs helper c (i:is) (x:xs) | c < i = x : helper (c+1) (i:is) xs | otherwise = f x : helper (c+1) is xs It works like this: mapAtOriginal (*2) [0,3] [1,2,3,4] -- == [2,2,3,8] So I want to rewrite it but using a map function. I understand that map applies to every element of the list, however, I need it applied only for specific indices. How can I do it? 回答1: map

问题 This is homework, so I don't want the answer. I only need a push in the right direction. I am required to map multiple functions onto a list. For instance: (map-multi (list plus-one square) '(4 5 6)) => (25 36 49) I am able to have it map the first function to the elements of the list, however, I get very lost after that. Also, since this is introductory, I am limited to introductory functions ( const , append , car , cdr , member , etc.) (define (map-multi f l) (cond ((null? l) l) (else

问题 This question already has answers here : Python 3 vs Python 2 map behavior (3 answers) Closed 3 years ago . I am doing the following in Python2.7: >>> a = [1,2,3,4,5] >>> b = [2,1,3,4] >>> c = [3,4] >>> map(None, a, b, c) [(1, 2, 3), (2, 1, 4), (3, 3, None), (4, 4, None), (5, None, None)] I am trying to do something similar in Python3 >>> a = [1,2,3,4,5] >>> b = [2,1,3,4] >>> c = [3,4] >>> map(None, a, b, c) <map object at 0xb72289ec> >>> for i,j,k in map(None, a, b, c): ... print (i,j,k) ...

问题 Lets say I want to do the following: (define (foo lst x) (filter function lst) but function takes in 2 arguments (and function was given to me), one being the list lst it will use, and the other being x . Syntactically, how would I change that line to pass in the second argument? Sorry I am new to Scheme/DrRacket. 回答1: Try this, using curry: (define (foo lst x) (filter (curry function x) lst)) That is, assuming that function takes as first parameter x and as second parameter each one of the

问题 I am building a microsimulation model in Julia. I have built the structure of my function and it runs great for for 1 "person". I'd like to write the script to run 100000+ people through the model and save the results in one location. Eventually I'd like to execute this in parallel. Below I have included a simple working version of the code with dummy probabilities. using Distributions # Microsim function function MicroSim(start_age, stages) stage = 0 age = start_age # Set all trackers to 0