Why am I getting this error: "argument is not numeric or logical: returning NA"?

Why am I getting this error: "argument is not numeric or logical: returning NA"?

我试图在数据集中查找此列的平均值,但是,它显示警告并且没有给我结果。

这是我试过的代码:

mean(SurveyInsta$Usage_duration)

这是我收到的警告信息:

>[1] NA
>Warning message:
>In mean.default(SurveyInsta$Usage_duration) :
>argument is not numeric or logical: returning NA

试试这个:

mean(as.numeric(SurveyInsta$Usage_duration), na.rm = TRUE)