r - 使用两个不同的变量时如何进行子集化（制作条形图）

Question

我正在尝试使用两个不同的变量创建一个子集，但是当我运行此代码时：

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

它出现了这个错误信息：

子集错误==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表格来运行条形图：

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

barplot(democrats.table)

Answer 1

难道你试图传递一个变量而不是一个字符串（比如"progressive.vote"）？欢迎进一步澄清。

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