if-statement

问题 I'm trying to apply the same condition for multiple columns of an array and, then, create a new column if any of the columns meet the condition. I can do it manually with an OR statement, but I was wondering if there is an easy way to apply it for more columns. An example: data <- data.frame(V1=c("A","B"),V2=c("A","A","A","B","B","B"),V3=c("A","A","B","B","A","A")) data[4] <- ifelse((data[1]=="A"|data[2]=="A"|data[3]=="A"),1,0) So the 4th row is the only that doesn't meet the condition for

问题 I'm trying to apply the same condition for multiple columns of an array and, then, create a new column if any of the columns meet the condition. I can do it manually with an OR statement, but I was wondering if there is an easy way to apply it for more columns. An example: data <- data.frame(V1=c("A","B"),V2=c("A","A","A","B","B","B"),V3=c("A","A","B","B","A","A")) data[4] <- ifelse((data[1]=="A"|data[2]=="A"|data[3]=="A"),1,0) So the 4th row is the only that doesn't meet the condition for

问题 I am trying to loop the switch condition if the choice is out of range. But i am not getting the desired output. So if while going through the switch condition the user does not input 1-3 as input, i want it to go to default condition which should trigger the error statement and then keep looping Console.WriteLine("Which book would you like to check out?"); Console.WriteLine("select 1 for book 1, 2 for book 2, and 3 for book 3"); int choice=Convert.ToInt32(Console.ReadLine()); bool loopBreak

问题 So I am trying to code a program in arduino that does a task for 2 minutes and then another task for 5 mins. first one and then the other in a loop until a different condition is met. Ive been trying to do this with if statements and while loops but im getting lost in the time part i think //Pneumatic feed system double minute = 1000*60; double vibTime = 2 * minute; //2 mins //double vibTime = 5000; double execTime = millis(); double waitTime = 5 * minute; //time waits between vibrating /

问题 I want users to be able to delete comments they have written. Unfortunately though I can not get the if statement to work. {% if comment.name == user %} <a href="{% url 'delete_own_comment' comment.id %}">delete this comment-</a> {% endif %} So I could see the value of user and comment.name I included the below code. This was for testing purposes and would not be included in the sites final design. <h3 class="article-content">{{ user }}</h3> <p class="article-content">{{ comment.name }}</p> I

问题 Note: It's true that this question has been answered for many other languages. However, I could not find an answer for Python, so do not mark as duplicate. Is there a difference in performance between the if-else statement and the ternary operator in Python? 回答1: I doubt there is a performance difference. They compile to equivalent sequences of bytecodes: >>> def f(): ... return a if b else c ... >>> dis.dis(f) 2 0 LOAD_GLOBAL 0 (b) 2 POP_JUMP_IF_FALSE 8 4 LOAD_GLOBAL 1 (a) 6 RETURN_VALUE >>

问题 Is it possible to write an else at the end of an if -row which only gets executed if none of all the if statements are true? Example: if foo==5: pass if bar==5: pass if foobar==5: pass else: pass In this example, the else part gets executed if foobar isn't 5, but I want it to be executed if foo , bar and foobar aren't 5. (But, if all statements are true, all of them have to be executed.) 回答1: I don't think there's any overly elegant way to do this in Python or any other language. You could

问题 I came across code which I somehow find 'odd'. var = None try: var = mydict[a][b] except: pass I'm not very comfortable with using try-except for checking dict key, when obviously there is an if-else sequence to handle the same situation. var = None if a in mydict: if b in mydict[a]: var = mydict[a][b] Is there any 'obvious' advantage/disadvantage of using one approach over the other? 回答1: Exception handling is generally much slower than an if statement. With the presence of nested

问题 Im trying to keep my code clean and especially using Comboboxes in userforms there can be a lot of if Elseif statements. There should be an easier way to not have multiple pages of code for just one combobox is there? Example of how it is done now: Sub Example() Dim Variable as String If Combobox1.Value = "Option1" Then Variable = "Name1" Elseif Combobox1.Value = "Option2" Then Variable = "Name2" Elseif Combobox1.Value = "Option3" Then Variable = "Name3" Elseif Combobox1.Value = "Option4"

问题 I would like to create a column d, which includes all the non-NA values from the other columns. I tried ifelse, but cannot figure out how to make it nested in the proper manner, so that the value in column c is included as well.. Perhaps something else than ifelse should be used? Here is a "dummy" dataframe: a <- c(NA, NA, NA, "A", "B", "A", NA, NA) b <- c("D", "A", "C", NA, NA, NA, NA, NA) c <- c(NA, NA, NA, NA, NA, NA, "C", NA) data <- data.frame(a, b, c) I would like the d column to look