在R中查找并替换分类变量

Question

x1 <- c("agree","disagree","agree","agree","agree","disagree","disagree")

如何替换数据框中的大型原子矢量或特定行/列的agree=1和disagree=0？

Answer 1

你可以做这样的事情

ifelse(x1 == 'agree', 1, 0)

可以根据需要添加更多条件。

Answer 2

我们可以使用+将逻辑转换为二进制

+(x1=="agree")

或使用as.integer（根据评论）

as.integer(x1 == "agree")

此方法比ifelse快得多。

 set.seed(24)
 x2 <- sample(c("agree", "disagree"), 1e7, replace=TRUE)
 system.time(+(x2=="agree"))
 #  user  system elapsed 
 #  0.32    0.06    0.40 
 system.time(ifelse(x2=="agree", 1,0))
 #  user  system elapsed 
 #   3.20    0.91    4.10