loops

问题 I have always had the idea that reducing the number of iterations is the way to making programs more efficient. Since I never really confirmed that, I set out to test this. I made the following C++ program that measures the time of two different functions: The first function does a single large loop and uses a set of variables. The second function does multiple equally large loops, but a single loop per variable. Complete test code: #include <iostream> #include <chrono> using namespace std;

问题 I have always had the idea that reducing the number of iterations is the way to making programs more efficient. Since I never really confirmed that, I set out to test this. I made the following C++ program that measures the time of two different functions: The first function does a single large loop and uses a set of variables. The second function does multiple equally large loops, but a single loop per variable. Complete test code: #include <iostream> #include <chrono> using namespace std;

问题 I'm looking for a Tidyverse / broom solution that can solve this puzzle: Let's say I have different DVs and a specific set of IVS and I want to perform a regression that considers every DV and this specific set of IVs. I know I can use something like for i in or apply family, but I really want to run that using tidyverse . The following code works as an example ds <- data.frame(income = rnorm(100, mean=1000,sd=200), happiness = rnorm(100, mean = 6, sd=1), health = rnorm(100, mean=20, sd = 3),

问题 I'm looking for a Tidyverse / broom solution that can solve this puzzle: Let's say I have different DVs and a specific set of IVS and I want to perform a regression that considers every DV and this specific set of IVs. I know I can use something like for i in or apply family, but I really want to run that using tidyverse . The following code works as an example ds <- data.frame(income = rnorm(100, mean=1000,sd=200), happiness = rnorm(100, mean = 6, sd=1), health = rnorm(100, mean=20, sd = 3),

问题 I have an extensive block of code that I've written using dplyr syntax in R. However, I am trying to put that code in a loop, so that I can ultimately create multiple output files as opposed to just one. Unfortunately, I appear unable to do so. For illustration purposes regarding my problem, let's refer to the commonly used "iris" dataset in R: > data("iris") > str(iris) 'data.frame': 150 obs. of 5 variables: $ Sepal.Length: num $ Sepal.Width : num $ Petal.Length: num $ Petal.Width : num $

问题 I need to iterate through a BucketMap and get all keys but how do I get to something like buckets[i].next.next.next.key for instance without doing it manually as I tried here: public String[] getAllKeys() { int j = 0; //index of string array "allkeys" String allkeys[] = new String[8]; for(int i = 0; i < buckets.length; i++) { //iterates through the bucketmap if(buckets[i] != null) { //checks wether bucket has a key and value allkeys[j] = buckets[i].key; //adds key to allkeys j++; // counts up

问题 I'd like to ask how to execute 1 command multiple times for example this code System.out.println("Hello World!"); I want to run it 500 times how do i do it ? Thank You Regards Wilhelmus 回答1: Use a loop, for(int i = 0; i < 500; ++i) System.out.println("Hello World!"); Please go through a basic Java tutorial. One can be found here 回答2: With Java 8 Streams you could do it like that IntStream.range(0, 500).forEach(i -> System.out.println("Hello World!")); 回答3: You would use a for loop. for(int i

问题 I have a dataframe like this import seaborn as sns import pandas as pd %pylab inline df = pd.DataFrame({'a' :['one','one','two','two','one','two','one','one','one','two'], 'b': [1,2,1,2,1,2,1,2,1,1], 'c': [1,2,3,4,6,1,2,3,4,6]}) A single boxplot is OK sns.boxplot( y="b", x= "a", data=df, orient='v' ) But i want to build a subplot for all variables. I do names = ['b', 'c'] plt.subplots(1,2) sub = [] for name in names: ax = sns.boxplot( y=name, x= "a", data=df, orient='v' ) sub.append(ax) and i

问题 This question already has answers here : Closed 8 years ago . Possible Duplicate: python, basic question on loops how to let a raw_input repeat until I wanna quit? I would like some help with Python please. I'm writing a program in Py2.7.2, but am having some issues. What I have so far is something like this: choice = raw_input("What would you like to do") if choice == '1': print("You chose 1") elif choice == '2': print("You chose 2") elif choice == '3': print("You chose 3") else: print("That

问题 I have created a code which basically generates a random 20 digit number. Code below: import random from random import randint n=20 def digit(n): range_start = 10**(n-1) range_end = (10**n)-1 return randint(range_start, range_end+1) print(digit(n)) The output of this code for example is: 49690101904335902069 Now given this code I'm just wondering how I can go about to counting the number of zeros in the output, so essentially I'm trying to create a new function called count_zero(): , but I