assign

问题 Is there a simpler alternative than res = returns_value_or_none(arg) if res: do_something_with(res) or if returns_value_or_none(arg): do_something_with(returns_value_or_none(arg)) One which combines the assignment and if conditional into one statement? 回答1: Often, what you have is already the best option. You can always create a new scope to bind the value to a variable: (lambda res: do_something_with(res) if res else None)(returns_value_or_none(arg)) But that's certainly not going to be more

问题 I'm trying to change the field in the array. I used find function to get the object and then I used Object.assign to overwrite the value from the array. However, in one case it works: Object.assign(item2, {id:3, name: "Do"}); and in the other case, it doesn't: item = Object.assign({}, {id:3, name: "Do"}); What's different for those two cases? let arr = [{id:1, name:"John"}, {id:2, name: "Doe"}]; let item = arr.find((x)=> x.id === 2); //the array is not changed! item = Object.assign({}, {id:3,

问题 How to assign a value to the first n elements of a vector? Say, I want to assign 1 to a vector from index 0 to index 4. I already have a vector with size 11. Now I want to put 1 to the first 5 elements. 回答1: You can use std::fill or std::fill_n: std::fill(v.begin(), std::next(v.begin(), 5), 1); std::fill_n(v.begin(), 5, 1); Note: std::next is C++11. In this case it can be replaced by v.begin() + 5 . 回答2: If you want to construct a vector filled like that, use the suitable constructor: std:

问题 I have begun to take my first steps in learning python and am trying to start using classes. I have this simplified version so far: class ThingsInTheFridge(object): def __init__(self): self.milk = False self.yogurt = False self.bread = True self.umbrella = True There will be about 30 things in my class and each is assigned True or False (I have shortened the list for this question). What is the most efficient way to assign them? I have thought about this but it doesn't seem to improve things

问题 This is my first week working with R and there is one thing about function I cannot seems to manage. df <- data.frame(a = c(1:10), b = c("a", "a", "b", "c", "c", "b", "a", "c", "c", "b")) testF = function(select) { dum = subset(df, b == select) } lapply(unique(df$b), testF) This function now just prints the the data sets on screen. But I would like to store the results as separate data frames in my workspace. In this example this would give three data frames; a, b and c. Thank for the help.

问题 This question already has answers here : How can I merge properties of two JavaScript objects dynamically? (60 answers) Why can't I assign a new value to “this” in a prototype function? (4 answers) Closed 3 years ago . I'm trying to merge the props from values into this . The following throws an error. How can I do this? this = {...this, ...values} 回答1: You could extend this with Object.assign method: class Foo { constructor (props) { Object.assign(this, props); } } const foo = new Foo({ a: 1

问题 I am trying to assign unique values in pandas df to specific individuals. For the df below, [Area] and [Place] will together make up unique values that are various jobs . These values will be assigned to individuals with the overall aim to use the least amount of individuals possible. The trick is these values are constantly starting and finishing and go for different lengths of time. The most unique values assigned to an individual any one time is 3 . [On] displays how many current unique

问题 I'm looking to create multiple data frames using a for loop and then stitch them together with merge() . I'm able to create my data frames using assign(paste(), blah) . But then, in the same for loop, I need to delete the first column of each of these data frames. Here's the relevant bits of my code: for (j in 1:3) { #This is to create each data frame #This works assign(paste(platform, j, "df", sep = "_"), read.csv(file = paste(masterfilename, extension, sep = "."), header = FALSE, skip = 1,

问题 Ok so I have never worked with fstream before or opened and read and files in a program. My instructor just gave a few lines of code that open, read, and close a text file. I'm supposed to take the data out of the text file and put it into separate nodes in a linked list and then go on to do other things with it which is not important because I know how to do it. My problem is that I don't know how to a assign these values to the struct values. The txt file looks like this: Clark Kent 55000

问题 Just started Haskell, it's said that everything in Haskell is "immutable" except IO package. So when I bind a name to something, it's always something immutable? Question, like below: Prelude> let removeLower x=[c|c<-x, c `elem` ['A'..'Z']] Prelude> removeLower "aseruiiUIUIdkf" "UIUI" So here: 1. “removeLower" is an immutable? Even it's a function object? But I can still use "let" to assign something else to this name. 2. inside the function "c<-x" seems that "c" is a variable. It is assigned