正如标题所说，我有一个包含y变量和4个x变量的txt文件：
playtennis outlook temperature humidity wind
1 no sunny hot high weak
2 no sunny hot high strong
3 yes overcast hot high weak
4 yes rain mild high weak
5 yes rain cool normal weak
6 no rain cool normal strong
目标是用分类树预测y变量（playtennis）。
所以我决定做一套训练课程：
SamSize <- floor(0.25*nrow(input.dat))
train_ind <- sample(seq_len(nrow(input.dat)), size = SamSize)
train <- input.dat[train_ind, ]
test <- input.dat[-train_ind, ]
然后使用rpart创建分类树：
tree1 = rpart(playtennis ~ outlook + temperature + humidity + wind, data = test, subset = train, method = "class",cp=0.001,xval=20)
但是我收到了错误：
Error in `[.default`(xj, i) : invalid subscript type 'list'
我无法弄清楚出了什么问题。
我是否需要将data.frame表转换为其他内容？ 我试过了
as.matrix(train)
as.matrix(test)
并没有解决问题（我想也许它无法识别输入）。
感谢您的建议！
编辑：这是dput（）文件，以防它有助于解决此问题。
structure(list(playtennis = structure(c(1L, 1L, 3L, 3L, 3L, 1L,
3L, 1L, 3L, 3L, 3L, 3L, 3L, 2L), .Label = c("no", "No", "yes"
), class = "factor"), outlook = structure(c(4L, 4L, 1L, 2L, 2L,
2L, 1L, 4L, 4L, 2L, 4L, 1L, 1L, 3L), .Label = c("overcast", "rain",
"Rain", "sunny"), class = "factor"), temperature = structure(c(2L,
2L, 2L, 3L, 1L, 1L, 3L, 3L, 1L, 3L, 3L, 2L, 1L, 4L), .Label = c("cool",
"hot", "mild", "Mild"), class = "factor"), humidity = structure(c(1L,
1L, 1L, 1L, 3L, 3L, 1L, 1L, 3L, 3L, 3L, 3L, 3L, 2L), .Label = c("high",
"High", "normal"), class = "factor"), wind = structure(c(2L,
1L, 2L, 2L, 2L, 1L, 1L, 2L, 2L, 2L, 1L, 2L, 1L, 1L), .Label = c("strong",
"weak"), class = "factor")