for-loop

问题 here is my js fiddle : http://jsfiddle.net/pYM38/16/ var box = document.getElementById('box'); var colors = ['purple', 'yellow', 'orange', 'brown', 'black']; box.onclick = function () { for (i = 0; i < colors.length; i++) { box.style.backgroundColor = colors[i]; } }; I'm in the process of learning JavaScript. I was trying to get this to loop through each color in the array, but when i click the box (demonstration on jsfiddle) it goes to the last element in the array. 回答1: Here are two methods

问题 here is my js fiddle : http://jsfiddle.net/pYM38/16/ var box = document.getElementById('box'); var colors = ['purple', 'yellow', 'orange', 'brown', 'black']; box.onclick = function () { for (i = 0; i < colors.length; i++) { box.style.backgroundColor = colors[i]; } }; I'm in the process of learning JavaScript. I was trying to get this to loop through each color in the array, but when i click the box (demonstration on jsfiddle) it goes to the last element in the array. 回答1: Here are two methods

问题 Goal: Take a data frame and create separate vectors for each of its columns (variables). The following code gets me close: batting <- read.csv("mlb_2014.csv", header = TRUE, sep = ",") hr <- batting[(batting$HR >= 20 & batting$PA >= 100), ] var_names <- colnames(hr) for(i in var_names) { path <- paste("hr$", i, sep = "") assign(i, as.vector(path)) } It creates the a vector for each column in the data frame as shown by the output below: > ls() [1] "AB" "Age" "BA" "batting" "BB" "CS" [7] "G"

问题 Goal: Take a data frame and create separate vectors for each of its columns (variables). The following code gets me close: batting <- read.csv("mlb_2014.csv", header = TRUE, sep = ",") hr <- batting[(batting$HR >= 20 & batting$PA >= 100), ] var_names <- colnames(hr) for(i in var_names) { path <- paste("hr$", i, sep = "") assign(i, as.vector(path)) } It creates the a vector for each column in the data frame as shown by the output below: > ls() [1] "AB" "Age" "BA" "batting" "BB" "CS" [7] "G"

问题 i understand that to create dynamic for loops, recursive or itertools module in python is the way to go. Lets say I am doing it in recursive. What I want is for var1 in range(var1_lowerlimit, var1_upperlimit, var1_stepsize): for var2 in range(var2_lowerlimit, var2_upperlimit, var2_stepsize): : : # do_whatever() repeat for n loops where n is the number of variables What I have now is I have 2 lists variable_list = [ var1, var2, var3, ... ] boundaries_list = [ [var1_lowerlimit, var1_upperlimit,

问题 I know there are better ways to search an array, but I really want to understand how to return when the value is found in a recursive call. Logging when found isn't a problem, but I can't seem to make this return true when found. The problem is basic. Fully search multi-dimensional array for a value and return true if found or false if not found, using a for loop and recursion. I've tried returning the recursive function and everything else I can think of, but nothing works fully. function

问题 In this post, the following code snippets could work. a = [0, 1, 2, 3] for a[-1] in a: print(a[-1]) Refer to this answer While doing for a[-1] in a , you actually iterate through the list and temporary store the value of the current element into a[-1] . Likewise, I think doing for a in a , it should iterate through the list and temporary store the value of current element to a , so the value of a could be 0 , and is not iterable, then TypeError exception will be thrown in the next iteration.

问题 Is there any difference between the two following statements. They achieve the same end, correct? Do they compile to the same Java code? Is there any performance difference between them or is it just a matter of preference/readability? for (thing <- things) { doSome(thing) } things.foreach( thing => doSome(thing) ) 回答1: for comprehensions are defined as simple syntactic translations. That's extremely important, because that allows any object to work with for comprehensions, it just has to

问题 So I am have this issue with Google Apps Script. It is timing out because the app server requests are taking too long. I was just wanting to see if my coding could be cleaned up a bit to run faster or is there another method which would work? Code below: for (var y = 1; y < listLast ; y++) { var matchor = listSheet.getRange("B" + y).getValue(); var listEmCo = listSheet.getRange("A" + y).getValue(); if(matchor == "Match") { Logger.log("Do Nothing"); } else { for (var x = 0; x < formLast; x++)

问题 So I am have this issue with Google Apps Script. It is timing out because the app server requests are taking too long. I was just wanting to see if my coding could be cleaned up a bit to run faster or is there another method which would work? Code below: for (var y = 1; y < listLast ; y++) { var matchor = listSheet.getRange("B" + y).getValue(); var listEmCo = listSheet.getRange("A" + y).getValue(); if(matchor == "Match") { Logger.log("Do Nothing"); } else { for (var x = 0; x < formLast; x++)