将数字重新编码为字符串不会替换所有值

Question

有人可以解释为什么只有部分数字被转换为高低字符串？

set.seed(1)
df <- data.frame(npitotal=ceiling(runif(30,0,40)))
df$npitotal[df$npitotal >= 22] <- "high"
df$npitotal[df$npitotal < 22] <- "low"

df$npitotal
# [1] "low"  "low"  "high" "high" "9"    "high" "high" "high"
# [9] "high" "3"    "9"    "8"    "high" "low"  "high" "low" 
#[17] "high" "high" "low"  "high" "high" "9"    "high" "6"   
#[25] "low"  "low"  "low"  "low"  "high" "low"

Answer 1

我最终的解决方案是在汽车套件中使用recode：

library(car)
recode(df$npitotal,"0:21='low';22:40='high'")

注意0:21是[0,21]（所以20.99评估为“低：在这种情况下）

感谢@Jay解释导致问题的原因：

进行第一次转换后，它变成了一个字符向量 - 所以第二次转换不是以数字方式进行评估，而是作为一个字符。