R滞后变量和跳过值之间

【问题标题】：R Lag Variable And Skip Value BetweenR滞后变量和跳过值之间
【发布时间】：2022-11-24 04:13:01
【问题描述】：

DATA = data.frame(STUDENT = c(1,1,1,2,2,2,3,3,4,4),
                  SCORE = c(6,4,8,10,9,0,2,3,3,7),
                  CLASS = c('A', 'B', 'C', 'A', 'B', 'C', 'B', 'C', 'A', 'B'),
                  WANT = c(NA, NA, 2, NA, NA, -10, NA, NA, NA, NA))

我有 DATA 并希望创建通过以下方式计算的“WANT”：

对于每个学生，找到 SCORE，其中 SCORE 等于 SCORE(CLASS = C) - SCORE(CLASS = A)

EX: SCORE(STUDENT = 1, CLASS = C) - SCORE(STUDENT = 1, CLASS = A) = 8-6=2

【问题讨论】：

标签： r dplyr case lag

【解决方案1】：

尝试

library(dplyr)
DATA <- DATA %>%
   group_by(STUDENT) %>% 
   mutate(WANT2 = (SCORE[CLASS == 'C'][1] - SCORE[CLASS == 'A'][1]) * 
       NA^(CLASS != "C")) %>%
   ungroup

-输出

# A tibble: 10 × 5
   STUDENT SCORE CLASS  WANT WANT2
     <dbl> <dbl> <chr> <dbl> <dbl>
 1       1     6 A        NA    NA
 2       1     4 B        NA    NA
 3       1     8 C         2     2
 4       2    10 A        NA    NA
 5       2     9 B        NA    NA
 6       2     0 C       -10   -10
 7       3     2 B        NA    NA
 8       3     3 C        NA    NA
 9       4     3 A        NA    NA
10       4     7 B        NA    NA

【讨论】：