r - 因子水平无效，NA 生成警告

Question

这个问题在这里已经有了答案:





Warning message: In `...` : invalid factor level, NA generated

(5 个回答)


7年前关闭。




与此处提出的另一个问题类似，我在主题行中收到错误消息。我试图使用它的补救措施来解决我的问题，但我无法这样做。这是我的代码:

#Change the format of IED deaths to be uniform
USdata$Cause[USdata$Cause=="Hostile - hostile fire - IED attack" | USdata$Cause=="Hostile - hostile fire - IED attack (suicide attack)" | USdata$Cause=="Hostile - hostile fire - IED attack (suicide car bomb)" | USdata$Cause=="Hostile - hostile fire - IED attack (while defusing)" | USdata$Cause=="Hostile - hostile fire - IED attack, RPG" | USdata$Cause=="Hostile - hostile fire - IED attack, RPG, small arms fire" | USdata$Cause=="Hostile - hostile fire - IED Attack, small arms fire" | USdata$Cause=="Hostile - hostile fire - IED Attack, small arms fire, indirect fire"] <- "Hostile - IED Attack"

Warning message:
In `[<-.factor`(`*tmp*`, USdata$Cause == "Hostile - hostile fire - IED attack" |  :
 invalid factor level, NA generated

我看到当我对我尝试的新值“敌对 - 简易爆炸装置攻击”进行总结时，我得到的所有内容都以 NA 的形式返回。我能够用其他值做类似的事情，但这个不是那么容易。谢谢。

Answer 1

首先从一个因子转换它，进行更改并重新转换回来。另外，%in%从长远来看，可能对您更有效:

ied_causes <- c("Hostile - hostile fire - IED attack",
                "Hostile - hostile fire - IED attack (suicide attack)",
                "Hostile - hostile fire - IED attack (suicide car bomb)",
                "Hostile - hostile fire - IED attack (while defusing)",
                "Hostile - hostile fire - IED attack, RPG",
                "Hostile - hostile fire - IED attack, RPG, small arms fire",
                "Hostile - hostile fire - IED Attack, small arms fire",
                "Hostile - hostile fire - IED Attack, small arms fire, indirect fire")

USdata$Cause <- as.character(USdata$Cause)
USdata$Cause[USdata$Cause %in% ied_causes] <- "Hostile - IED Attack"
USdata$Cause <- factor(USdata$Cause)