在R中按State和Filter分组生成计数表并添加计数列

你需要用dplyr的group_by()配合mutate()来实现，tally()会将每组聚合为单行，不符合你保留原数据所有行的需求。具体代码如下：

library(dplyr)

data1 <- data.frame(
  State = c("NJ", "NJ", "PA", "NJ", "TX"),
  Filter = c("Filter", "Filter", "No Filter", "Filter", "Filter"),
  Threshold = c("Exceeds","Exceeds", NA, "NL", "Exceeds")
)

final_data <- data1 %>%
  group_by(State, Filter) %>%
  mutate(
    Count_Exceeds_Threshold = sum(Threshold == "Exceeds", na.rm = TRUE),
    Count_Total = n()
  ) %>%
  ungroup()

# 查看结果
final_data

代码说明 #

• group_by(State, Filter)：按State和Filter两个字段分组
• Count_Exceeds_Threshold = sum(Threshold == "Exceeds", na.rm = TRUE)：统计每组中Threshold等于"Exceeds"的次数，na.rm = TRUE确保NA值不干扰统计结果
• Count_Total = n()：直接获取每组的总记录数
• ungroup()：取消分组状态，避免后续操作受分组限制

运行后得到的结果和你期望的final_data完全一致。

内容的提问来源于stack exchange，提问作者Sarah