如何在R中从数据集中选择多个模式

data <- c("apple", "banana", "avocado", "orange")
pattern <- "^a"  # 匹配以字母"a"开头的模式
matches <- grep(pattern, data, value = TRUE)

data <- c("apple", "banana", "avocado", "orange")
matches <- data[str_length(data) == 3 & str_sub(data, 1, 1) == "a"]

library(caret)
data <- data.frame(x = c(1, 2, 3, 4, 5), y = c("a", "b", "a", "b", "a"))
model <- train(y ~ x, data = data, method = "rpart")
predicted <- predict(model, newdata = data)
matches <- data[predicted == "a", ]