R中的Data.frame：两列的连接，数字而不是出现

Question

我有一个非常简单的问题，但我找不到答案：我有这个data.frame：

b=c("a","a","a","a","a","b","b","b","b","c")
c=c("b","b","b","b","b","c","c","c","c","d")

a<-data.frame(b,c)

为什么我要将a$b和a$c向量放在一列中：

f<-c(a$b,a$c)

结果不像

> f<-c(b,c)
> f
 [1] "a" "a" "a" "a" "a" "b" "b" "b" "b" "c" "b" "b" "b" "b" "b" "c" "c" "c" "c" "d"

但

> f<-c(a$b,a$c)
> f
 [1] 1 1 1 1 1 2 2 2 2 3 1 1 1 1 1 2 2 2 2 3

？ 提前谢谢！

编辑： 试过这个，看看上面可能的重复建议：

> a<-data.frame(z=as.character(b),k=as.character(c))
> f<-c(a$z,a$k)
> f  [1] 1 1 1 1 1 2 2 2 2 3 1 1 1 1 1 2 2 2 2 3

Answer 1

您必须在stringsAsFactors功能中将FALSE设置为data.frame()。否则，字符串将被解释为因子，从而导致您的意外输出。

b <- c("a","a","a","a","a","b","b","b","b","c")
c <- c("b","b","b","b","b","c","c","c","c","d")

a <- data.frame(b,c, stringsAsFactors = F)

f <- c(a$b,a$c)

f
[1] "a" "a" "a" "a" "a" "b" "b" "b" "b" "c" "b" "b" "b" "b" "b" "c" "c" "c" "c" "d"