dplyr字符串匹配和替换基于R中的查找表

Question

我正在尝试实现我以前在Excel中执行的功能,但无法找到实现它的方法.

我有两个数据集:一个是我的基础数据集,另一个是查找表.我的基地有两列,人的名字和姓氏.我的查找表也包含前两列,但它还包含替换的名字.

People <- data.frame(
  Fname = c("Tom","Tom","Jerry","Ben","Rod","John","Perry","Rod"),
  Sname = c("Harper","Kingston","Ribery","Ghazali","Baker","Falcon","Jefferson","Lombardy")
)

Lookup <- data.frame(
  Fname = c("Tom","Tom","Rod","Rod"),
  Sname = c("Harper","Kingston","Baker","Lombardy"),
  NewFname = c("Tommy","Tim","Roderick","Robert")
)

我想要做的是用NewFname替换Fname,这取决于两个条件:两个数据帧中的Fname和Sname匹配.这是因为我有一个数据集,其中包含需要处理的其他40,000行数据.最后,我希望最终得到以下数据框:

People <- data.frame(
  Fname = c("Tommy","Tim","Jerry","Ben","Roderick","John","Perry","Robert"),
  Sname = c("Harper","Kingston","Ribery","Ghazali","Baker","Falcon","Jefferson","Lombardy")
)

但是,我想要一个功能解决方案,所以我不必单独手动输入条件和替换名称.到目前为止,我有以下(有问题的)解决方案,这将涉及在dplyr中使用mutate生成一个新列,但它不起作用

 People %>%
  mutate(NewName = if_else(
    Fname == Lookup$Fname & Sname == Lookup$Sname, NewFname, Fname
  ))

Answer 1

只需使用a left_join然后再mutate打开!is.na()

library(dplyr)
People %>% 
  left_join(Lookup, by = c("Fname", "Sname")) %>% 
  mutate(Fname = ifelse(!is.na(NewFname), NewFname, Fname))
# Fname     Sname       NewFname
# 1    Tommy    Harper    Tommy
# 2      Tim  Kingston      Tim
# 3    Jerry    Ribery     <NA>
# 4      Ben   Ghazali     <NA>
# 5 Roderick     Baker Roderick
# 6     John    Falcon     <NA>
# 7    Perry Jefferson     <NA>
# 8   Robert  Lombardy   Robert

我离开时NewFname只是为了说明发生了什么.

数据:

People <- data.frame(
  Fname = c("Tom","Tom","Jerry","Ben","Rod","John","Perry","Rod"),
  Sname = c("Harper","Kingston","Ribery","Ghazali","Baker","Falcon","Jefferson","Lombardy"), stringsAsFactors = F
)

Lookup <- data.frame(
  Fname = c("Tom","Tom","Rod","Rod"),
  Sname = c("Harper","Kingston","Baker","Lombardy"),
  NewFname = c("Tommy","Tim","Roderick","Robert"), stringsAsFactors = F
)