我现在正在学习R,我意识到当我附加一个因子时,它就变成了一个字符.即使当我没有指定因子水平时,这种情况也会发生.当我查看数字的顺序时,我发现它们对应于"因子级别",例如,小是1.但是,我想知道为什么使用这种附加到向量的方法时会发生这种情况.
size_order <- factor(c("small", "medium", "large", "medium", "small", "small"), levels = c("small", "medium", "large"))
size order
> [1] small medium large medium small small
> Levels: small medium large huge
typeof(size_order)
> integer
但当我附加到它之后,它就变成了一个字符:
size_order <- append(size_order, "small")
size order
> "1" "2" "3" "2" "1" "1" "small"
typeof(size_order)
> [1] "character"