在R中查找并替换类别变量

问题描述

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

如何用大原子矢量或数据帧中特定的行/列替换agree=1和disagree=0?

How to replace agree=1 and disagree=0 for large atomic vectors or specific row/columns in a data frame?

推荐答案

我们可以使用+将逻辑转换为二进制

We can use + to convert the logical to binary

+(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

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