R 按组计算唯一值

发布于08月15日

    DATA = data.frame("TRIMESTER" = c(1,1,1,1,1,1,1,2,2,2,2,2,2,2,3,3,3,3,3,3,3,3,3),
                      "STUDENT" = c(1,2,3,4,5,6,7,1,2,3,5,9,10,11,3,7,10,6,12,15,17,16,21))
    
    WANT = data.frame("TRIMESTER" = c(1,2,3),
                      "NEW_ENROLL" = c(7,3,5),
                      "TOTAL_ENROLL" = c(7,10,15))

我有‘数据’，我想制作有三列的‘Want’，对于每个‘三学期’，你计算新的‘学生’的数量，然后对于‘Total_Enroll’，你只计算每个学期唯一的‘学生’的总数.

我的try 只计算每三个月的数量.

library(dplyr)
DATA %>%
group_by(TRIMESTER) %>%
count()

推荐答案

这里有一种方法.

suppressPackageStartupMessages(library(dplyr))

DATA <- data.frame("TRIMESTER" = c(1,1,1,1,1,1,1,2,2,2,2,2,2,2,3,3,3,3,3,3,3,3,3),
                  "STUDENT" = c(1,2,3,4,5,6,7,1,2,3,5,9,10,11,3,7,10,6,12,15,17,16,21))
DATA %>% 
  mutate(NEW_ENROLL = !duplicated(STUDENT)) %>%
  group_by(TRIMESTER) %>%
  summarise(NEW_ENROLL = sum(NEW_ENROLL)) %>%
  ungroup() %>%
  mutate(TOTAL_ENROLL = cumsum(NEW_ENROLL))
#> # A tibble: 3 × 3
#>   TRIMESTER NEW_ENROLL TOTAL_ENROLL
#>       <dbl>      <int>        <int>
#> 1         1          7            7
#> 2         2          3           10
#> 3         3          5           15

^{由reprex package(v2.0.1)于2022-08-14创建}