如何使用两个不同的变量进行子集化（制作一个条形图）

Question

我试图用两个不同的变量制作一个子集，但是当我运行这个代码时：

progressive.vote.demo <- subset(dbj, subset == progressive.vote & republican == 0)

它出现此错误消息：

子集中的错误== progressive.vote：比较（1）仅适用于原子和列表类型

这样我就可以制作一张桌子来运行一个条形图：

democrats.table <- table(democrats$judge.birthyear == "before 1935",
democrats$judge.birthyear == "from 1935", dbj$progressive.vote)

barplot(democrats.table)

Answer 1

可能是你试图传递变量而不是字符串（比如"progressive.vote"）？将会有更多的澄清。

dbj=as.data.frame(cbind(subset=c(rep("progressive.vote",2),rep("conservative.vote",2)),republican=c(0,1,0,1)))
dbj
     subset              republican
[1,] "progressive.vote"  "0"       
[2,] "progressive.vote"  "1"       
[3,] "conservative.vote" "0"       
[4,] "conservative.vote" "1"    

subset(dbj, subset == "progressive.vote" & republican == 0)
        subset republican
1 progressive.vote          0