如何串联因子，而不将其转换为整数级？ [英] How to concatenate factors, without them being converted to integer level?

问题描述

令我惊讶的是，当连接向量时，R将把因子强制转换为数字。即使级别相同，也会发生这种情况。例如：

I was surprised to see that R will coerce factors into a number when concatenating vectors. This happens even when the levels are the same. For example:

> facs <- as.factor(c("i", "want", "to", "be", "a", "factor", "not", "an", "integer"))
> facs
[1] i       want    to      be      a       factor  not     an      integer
Levels: a an be factor i integer not to want
> c(facs[1 : 3], facs[4 : 5])
[1] 5 9 8 3 1

在R中这样做的惯用方式是什么（在我的情况下，这些向量可能很大）？谢谢。

what is the idiomatic way to do this in R (in my case these vectors can be pretty large)? Thank you.

推荐答案

来自 R邮件列表：

unlist(list(facs[1 : 3], facs[4 : 5]))

To'cbind '因素，

To 'cbind' factors, do

data.frame(facs[1 : 3], facs[4 : 5])

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