str_replace_all 使用多个条件

Question

我有两个数据框（“之前”、“之后”）。

before1 <- c("A", "B", "C")
before2 <- c("1", "2", "3")
before3 <- c("ab", "cd", "ef")
before <- data.frame(before1, before2, before3)

after1 <- c("A", "B")
after2 <- c("1", "2")
after3 <- c("de", "fg")
after <- data.frame(after1, after2, after3)

当 before1 和 before2 同时匹配 after1 和 after3 时，我想用 after3 替换 before3。

我想要的结果如下。

before1 <-  c("A", "B" "C")
before2 <- c("1", "2", "3")
newafter <- c("de", "fg", "ef")

Answer 1

您可以加入两个数据框并使用coalesce 进行更新。

library(dplyr)

before %>%
  left_join(after,  by = c('before1' = 'after1', 'before2' = 'after2')) %>%
  mutate(newafter = coalesce(after3, before3)) %>%
  select(before1, before2, newafter)

#  before1 before2 newafter
#1       A       1       de
#2       B       2       fg
#3       C       3       ef