Пробовал пример в https://stat.ethz.ch/R-manual/R-devel/library/base/html/merge.html. Затем я обнаружил, что когда мы установили ALL = TRUE и all = TRUE в качестве параметра merge(), я просто получил другой результат (у одного 6 строк, а у другого 7 строк). Что случилось? Может ли кто-нибудь дать несколько советов? Спасибо.
> authors <- data.frame(
+ surname = I(c("Tukey", "Venables", "Tierney", "Ripley", "McNeil")),
+ nationality = c("US", "Australia", "US", "UK", "Australia"),
+ deceased = c("yes", rep("no", 4)))
> books <- data.frame(
+ name = I(c("Tukey", "Venables", "Tierney",
+ "Ripley", "Ripley", "McNeil", "R Core")),
+ title = c("Exploratory Data Analysis",
+ "Modern Applied Statistics ...",
+ "LISP-STAT",
+ "Spatial Statistics", "Stochastic Simulation",
+ "Interactive Data Analysis",
+ "An Introduction to R"),
+ other.author = c(NA, "Ripley", NA, NA, NA, NA,
+ "Venables & Smith"))
> m1<-merge(authors, books, by.x = "surname", by.y = "name", ALL = TRUE)
> m1
surname nationality deceased title other.author
1 McNeil Australia no Interactive Data Analysis <NA>
2 Ripley UK no Spatial Statistics <NA>
3 Ripley UK no Stochastic Simulation <NA>
4 Tierney US no LISP-STAT <NA>
5 Tukey US yes Exploratory Data Analysis <NA>
6 Venables Australia no Modern Applied Statistics ... Ripley
> m2<-merge(authors, books, by.x = "surname", by.y = "name", all = TRUE)
> m2
surname nationality deceased title other.author
1 McNeil Australia no Interactive Data Analysis <NA>
2 R Core <NA> <NA> An Introduction to R Venables & Smith
3 Ripley UK no Spatial Statistics <NA>
4 Ripley UK no Stochastic Simulation <NA>
5 Tierney US no LISP-STAT <NA>
6 Tukey US yes Exploratory Data Analysis <NA>
7 Venables Australia no Modern Applied Statistics ... Ripley