试图构建树给出：`[.default`（xj，i）中的错误：下标类型'list'无效

Question

运行以下代码：

library(tree)
library(ISLR)
library(dplyr)

Carseats <- Carseats %>% mutate(High = factor(ifelse(Sales <= 8, "No", "Yes")))

set.seed(2)
train_sample <- sample(nrow(Carseats), 200)
carseats_train <- Carseats[train_sample,]
carseats_test <- Carseats[-train_sample,]

tree.carseats <- tree(High~ . -Sales, Carseats, subset = carseats_train)

这将输出错误：

Error in `[.default`(xj, i) : invalid subscript type 'list'

这是什么原因，我该如何处理？

Answer 1

我发现了我的错误。我对树的输入不正确。即subset参数。这需要是一个表达式，指定要使用的子集。

可以通过使用train_sample作为输入来固定代码。

library(tree)
library(ISLR)
library(dplyr)

Carseats <- Carseats %>% mutate(High = factor(ifelse(Sales <= 8, "No", "Yes")))

set.seed(2)
train_sample <- sample(nrow(Carseats), 200)
carseats_test <- Carseats[-train_sample,]

tree.carseats <- tree(High~ . -Sales, Carseats, subset = train_sample)