infix-notation

问题 In an earlier post, I asked about declaring such functions in R packages and making them work. Having succeeded, I'm now trying to document one such function. I created an Rd file with the function's name as a title, but when running the CHECK , I get the following warning: * checking for missing documentation entries ... WARNING Undocumented code objects: '%IN%' I tried several names such as %IN%.Rd or '%IN%'.Rd , to no avail. Any hints on how to make this work? 回答1: The goto guide would

问题 I'm writing a program that takes user input and uses stacks to convert an infix expression into a postfix expression based on precedence, with operands always going before operators. For example, if a user inputs: (a+b*c) then the program should display: abc*+ so far, I have this: #include <iostream> #include <stack> #include <string> using namespace std; int main() { stack<char> s; char input; while (cin.get(input) && input != '\n') { if (isalnum(input)) cout << input << "\n"; else if (input

问题 My eventual goal is to apply sql-where-clause-style queries to filter pandas dataframes. Some searching led me to pyparsing's infixNotation method. I found an example of infix notation here: http://nullege.com/codes/show/src%40p%40y%40pyparsing-2.0.2%40examples%40simpleBool.py/15/pyparsing.infixNotation/python# but that actually processes the notation, and I need to use the tree multiple times on different data. Looking for help with parse trees I found this: http://pyparsing.wikispaces.com

问题 I'm trying to write infix to postfix program in java using stack. Here is my code: import java.io.*; import java.util.*; public class ONP{ public static void main(String args[]) throws java.io.IOException, NumberFormatException ,EmptyStackException{ BufferedReader br= new BufferedReader(new InputStreamReader(System.in)); int n=Integer.parseInt(br.readLine()); StringBuilder out= new StringBuilder(); Stack st=new Stack(); for(int i=0;i<n;i++){ String input=br.readLine(); char in[]=input

问题 i recently wrote a java program that takes an infix expression and converts it into a postfix expression. It works for the most part but i am getting wrong outputs for some expressions. For example the expression a+b+c+d+e will output abcde+++++ when it should output a b + c + d + e +. import java.util.Stack; public class ITP { public static Stack<Character> stack; public static String inFixExp; public static String postFixExp = ""; public static String infixToPostfix(String exp){ ITP o = new

问题 Why is f <$> g <$> x equivalent to (f . g) <$> x although <$> is not right-associative? (This kind of equivalence is valid in a popular idiom with plain $ , but currently $ is right-associative!) <*> has the same associativity and precedence as <$> , but behaves differently! Example: Prelude Control.Applicative> (show . show) <$> Just 3 Just "\"3\"" Prelude Control.Applicative> show <$> show <$> Just 3 Just "\"3\"" Prelude Control.Applicative> pure show <*> pure show <*> Just 3 <interactive>

问题 I need a function that takes an infix string (like "3 + 4 * 9"), and convert it to postfix (like "4 9 * 3 +"). I got it working until you throw in parentheses within parentheses. I've been working on it all day and can't figure out what I'm doing wrong- can someone with a fresh mind see it, maybe? I feel like I'm really close! Thanks! Here's the code: string ExpressionManager::infixToPostfix(string infixExpression) { cout << "itop Testing : " << infixExpression << endl; string posnums =

问题 A mathematical expression is usually expressed in infix notation. For evaluation purposes, we can change it to postfix (reverse polish) notation (using algorithms like Shunting-Yard) and then evaluate the postfix notation using stack. I found out that calculators use this technique, but do today's modern compilers use this for arithmetic expression evaluation? Is it efficient enough or other techniques (or algorithms) are being used? 回答1: To answer this question let's focus on the concepts

问题 Consider the following scenario: I have a class Test class Test() { infix fun say(msg: String) = println(msg) } and a main method fun main(args: Array<String>) { val test = Test() test say "Hello World!" //Works with(test) { say "Goodbye World!" //Does not work say("Hello again!") //Works } } As you can see I'm testing out the infix notation. Considering with(...) allows you to work with the object passed as parameter in the with block without having to access its members through the dot

问题 Suppose I have two custom infix operators in R: %foo% and %bar% . I have expressions that use both operators, such as: x %foo% y %bar% z How can I determine the operator precedence of %foo% and %bar% ? How can I change the precedence so that, for example, %bar% always executes before %foo% ? In the example above this would be the same as: x %foo% (y %bar% z) 回答1: I don't think this is explicitly documented, but implicit in the R language documentation is that infix operators are all of equal