r - 无法计算条件均值

Question

我有这个小数据集

structure(list(score = c("mine_score", "your_score", "mine_score", 
                            "your_score", "mine_score", "your_score"), points = c(53, 13.25, 
                                                                               17.5, 1.59090909090909, 48.5, 6.92857142857143)), row.names = c(NA, 
                                                                                                                                               -6L), class = c("tbl_df", "tbl", "data.frame"))

应用此公式时:

mean(long[long$score == 'mine_score', "points"], na.rm = TRUE)

我收到此错误，但无法找出原因:

Warning message:
In mean.default(long[long$score == "mine_score", "points"], na.rm = TRUE) :
  the argument is not numeric or logic: returns NA

有人可能知道这个错误是由什么引起的吗？ 谢谢

Answer 1

您的查询返回一个单列数据框，意味着无法理解；它必须返回一个向量。您可以使用 $ 返回向量:

mean(long$points[long$score == 'mine_score'], na.rm = TRUE)
#[1] 39.66667

---

如果您确实想坚持原始查询，可以使用 [[1]] 将数据帧的第一列作为向量返回:

mean(long[long$score == 'mine_score', "points"][[1]], na.rm = TRUE)