我有以下数据：
type <- c(1:4)
year1 <- c(1:4)
year2 <- c(1:4)
year3 <- c(1:4)
data <- data.frame(type, year1, year2, year3)
我想将Year列中的底部两行乘以2。
type <- c(1:4)
year1 <- c(1, 2, 6, 8)
year2 <- c(1, 2, 6, 8)
year3 <- c(1, 2, 6, 8)
final <- data.frame(type, year1, year2, year3)
如何在不影响列的其他行的情况下执行此操作？
答案 0 :(得分：2)
以下是使用package game;
import java.util.Scanner;
public class RouletteTester {
public static void main(String[] args) {
Scanner scanner = new Scanner (System.in);
int Mode;
System.out.println("Please choose how you'd like to play.");
System.out.println("To play by Odds & Evens, enter '1'");
System.out.println("To play by Numbers, enter '2'");
System.out.println("Enter game mode here: ");
Mode = scanner.nextInt();
System.out.println("You chose game mode " + Mode);
Scanner in = new Scanner (System.in);
System.out.print("Enter roulette number here: ");
int Number = in.nextInt();
RouletteWheel One = new RouletteWheel();
One.spin();
int r = One.getwinningNumber();
System.out.println(r);
if (r == Number)
System.out.println("Congratulations, The" + Number + " is a winning number!");
else
System.out.println("Sorry, " + Number + " is not a winning number.");
if (r == 0)
System.out.println("Congratulations, 0 is an automatic win!");
Scanner inn = new Scanner (System.in);
System.out.println("Odds or Evens? Type '1' for odds"
+ " or '2' for evens: ");
int Numberr = inn.nextInt();
if (Numberr == 1)
System.out.println("You choose Odds.");
else
System.out.println("You choose Evens.");
One.spin();
int winningNumber = One.getwinningNumber();
boolean n = One.OddEvenChoice();
System.out.println("The wheel landed on...");
System.out.println(winningNumber);
if ((n == true) && (winningNumber % 2 == 0))
System.out.println("You Win! E");
else if ((n == false) && (winningNumber %2 == 1))
System.out.println("You Win! O");
else
System.out.println("You Lose.");
}
}
和dplyr的解决方案。如果您愿意，这将允许您调整参数。
tidyr答案 1 :(得分：1)
如果您不知道数据的长度，并且您想要将所有包含“年”的列相乘，您可以这样做：
data[(nrow(data)-1):nrow(data),]<-data[(nrow(data)-1):nrow(data),grep(pattern="year",x=names(data))]*2
type year1 year2 year3
1 1 1 1 1
2 2 2 2 2
3 6 6 6 6
4 8 8 8 8