r - Dplyr 计数/多个过滤器计数

Question

我正在尝试创建一个 summarise/filter dplyr 管道，其等效于以下内容:

iris %>%
mutate(Sepal.Area = Sepal.Length * Sepal.Width,
       Petal.Area = Petal.Length * Petal.Width) %>%
  group_by(Species) %>%
      filter(Sepal.Area < 17) %>%
        tally() %>%
      filter(Sepal.Area > 17 & Sepal.Area < 22) %>%
        tally() %>%
      filter(Sepal.Area > 22) %>%
        tally()

或者另一种可能的方法:

iris %>%
  mutate(Sepal.Area = Sepal.Length * Sepal.Width,
         Petal.Area = Petal.Length * Petal.Width) %>%
  group_by(Species) %>%
    summarise(n(Sepal.Area < 17),
              n(Sepal.Area > 17 & Sepal.Area < 22),
              n(Sepal.Area > 22))

通过分组中的多个过滤器获取计数的最简单方法是什么？ 或者只是运行每个并稍后加入它们？

Answer 1

你可以尝试剪切:

iris %>%
    mutate(Sepal.Area = Sepal.Length * Sepal.Width,
           Petal.Area = Petal.Length * Petal.Width,
           range = cut(Sepal.Area, breaks = c(0, 17, 22, Inf))) %>%
    group_by(Species, range) %>%
    summarize(count = n())

#      Species    range count
#       <fctr>   <fctr> <int>
# 1     setosa   (0,17]    25
# 2     setosa  (17,22]    22
# 3     setosa (22,Inf]     3
# 4 versicolor   (0,17]    28
# 5 versicolor  (17,22]    21
# 6 versicolor (22,Inf]     1
# 7  virginica   (0,17]    10
# 8  virginica  (17,22]    31
# 9  virginica (22,Inf]     9