对于每一年，我想创建两个新列temp_count和rh_count，分别计算每个列temp_catog和humidity_catog中出现的次数。如果您按一个变量分组，How to count how many values per level in a given factor?会回答这个问题，但我想使用group_by(year, humidity_catog, temp_catog)。

我可以使用以下代码创建一个列humidity_count来计算每个类别humidity_catog列中出现的次数。

df <- group_by(year, humidity_catog) %>%
  summarize(humidity_count = n())

以下是输出

但是我想在同一个数据框中创建另一个列temp_count来统计每个类别temp_count列的数量，我该如何实现呢？下面是我通过dput函数创建的数据的可重现示例。

df <- structure(
  list(
    year = structure(
      c(1L, 1L, 1L, 1L, 1L, 1L, 1L,
        1L, 1L, 1L),
      .Label = c(
        "2006",
        "2007",
        "2012",
        "2013",
        "2014",
        "2014_c",
        "2015_a",
        "2015_b",
        "2016",
        "2017",
        "2020"
      ),
      class = "factor"
    ),
    min_rh = c(47.9, 49, 44.7, 40.2, 50, 52.3, 51.5, 82.8, 73.8,
               47.1),
    min_temp = c(12.4, 14.3, 15.1, 16.1, 12.7, 16.1, 14.4,
                 15.1, 11.8, 9.5),
    temp_catog = structure(
      c(2L, 2L, 3L, 3L,
        2L, 3L, 2L, 3L, 2L, 2L),
      .Label = c("T1(<=8)", "T2(>8, <=15)",
                 "T3(>15)"),
      class = "factor"
    ),
    humidity_catog = structure(
      c(1L,
        1L, 1L, 1L, 1L, 1L, 1L, 2L, 2L, 1L),
      .Label = c("RH1(<=65)",
                 "RH2(>65)"),
      class = "factor"
    )
  ),
  class = c("grouped_df",
            "tbl_df", "tbl", "data.frame"),
  row.names = c(NA,-10L),
  groups = structure(
    list(
      year = structure(
        1L,
        .Label = c(
          "2006",
          "2007",
          "2012",
          "2013",
          "2014",
          "2014_c",
          "2015_a",
          "2015_b",
          "2016",
          "2017",
          "2020"
        ),
        class = "factor"
      ),
      .rows = structure(
        list(1:10),
        ptype = integer(0),
        class = c("vctrs_list_of",
                  "vctrs_vctr", "list")
      )
    ),
    class = c("tbl_df", "tbl", "data.frame"),
    row.names = c(NA,-1L),
    .drop = TRUE
  )
)

注意：我不需要唯一的匹配项。我只需要计算每个类别被记录的次数。