for-loop

问题 I'm going over looping with tidyverse and purrr using Hadley's R4DS book and am a little confused as to the exact usage of the tilde ~ symbol and period symbol. So when writing for loops, or using map(), instead of writing out function(), it appears you can use the tilde symbol instead ~. Does this only apply to for loops? so as below... models <- mtcars %>% split(.$cyl) %>% map(~lm(mpg ~ wt, data = .)) Additionally, the period i was told can be used "to refer to the current list element" .

问题 I'm going over looping with tidyverse and purrr using Hadley's R4DS book and am a little confused as to the exact usage of the tilde ~ symbol and period symbol. So when writing for loops, or using map(), instead of writing out function(), it appears you can use the tilde symbol instead ~. Does this only apply to for loops? so as below... models <- mtcars %>% split(.$cyl) %>% map(~lm(mpg ~ wt, data = .)) Additionally, the period i was told can be used "to refer to the current list element" .

问题 I'm going over looping with tidyverse and purrr using Hadley's R4DS book and am a little confused as to the exact usage of the tilde ~ symbol and period symbol. So when writing for loops, or using map(), instead of writing out function(), it appears you can use the tilde symbol instead ~. Does this only apply to for loops? so as below... models <- mtcars %>% split(.$cyl) %>% map(~lm(mpg ~ wt, data = .)) Additionally, the period i was told can be used "to refer to the current list element" .

问题 Is it possible in python to have a for-loop without index and item? I have something like the following: list_1 = [] for i in range(5): list_1.append(3) The code above works fine, but is not nice according to the pep8 coding guidelines. It says: "Unused variable 'i'". Is there a way to make a for-loop (no while-loop) without having neither the index nor the item? Or should I ignore the coding guidelines? 回答1: You can replace i with _ to make it an 'invisible' variable. See related: What is

问题 Closed . This question needs details or clarity. It is not currently accepting answers. Want to improve this question? Add details and clarify the problem by editing this post. Closed 1 year ago . Improve this question Here is my code here I made a loop which is supposed to break when the value of x becomes equal to the random number public class Bark { public static void main(String[] args) { for (double x = 0 ; x>-1 ; x++) { System.out.print(x + " "); if( x == Math.random()) { break; } } }}

问题 I have the following loop: for (let index = 0; index < 4; index++) { setInterval(function() { console.log(index) }, 1000); } How can I make it so that it console logs 0 the first second, 1 the second second, 2 the third second, 3 the fourth second, 0 the fifth second, and so on until the interval is cleared? 回答1: Here's a more-or-less-but-rather-more elegant solution using a generator function. Generator functions are useful here, as their execution can be paused by yield , and resumed by

问题 I have the following loop: for (let index = 0; index < 4; index++) { setInterval(function() { console.log(index) }, 1000); } How can I make it so that it console logs 0 the first second, 1 the second second, 2 the third second, 3 the fourth second, 0 the fifth second, and so on until the interval is cleared? 回答1: Here's a more-or-less-but-rather-more elegant solution using a generator function. Generator functions are useful here, as their execution can be paused by yield , and resumed by

问题 I'm running into a problem with a block of code I'm trying to develop at my job. Essentially, I'm creating a userform in excel where folks will enter data for railcars as they get loaded at a certain location (we'll call these "spot 1, spot 2, spot 3, etc."). Sometimes they'll have to move that car to a different spot, in which case I want them to be able to keep all the information on the railcar from the first/original entry, and then erase the data from the original spot once that's done.

问题 I'm running into a problem with a block of code I'm trying to develop at my job. Essentially, I'm creating a userform in excel where folks will enter data for railcars as they get loaded at a certain location (we'll call these "spot 1, spot 2, spot 3, etc."). Sometimes they'll have to move that car to a different spot, in which case I want them to be able to keep all the information on the railcar from the first/original entry, and then erase the data from the original spot once that's done.

问题 I am trying to iterate a list ["abc","def","ghi"] & each iteration generates a list which i need to set it to a variable in ansible. here is my current script: - name: add checks set_fact: CHECKS: "{% for cKey in checkKey %} {{ CHECKS|default([]) }} + {{ CHECKSMAP | map(attribute=cKey ) | list |join(',')}} {% endfor %}" which generates the following output which is a string & not a list how can i append to the single list similar to list += temp_list in a for loop ok: [127.0.0.1] => { "msg":