Data transformation in R: Splitting a level in two - r

Question

I've got a df with country-level data entered in 2003.
Several rows of data belong to a country named 'Federal Republic of Yugoslavia'.
These are two separate countries today and I want to duplicate these rows of data so that I can rename each set of rows to its respective modern country name.
data.frame(Country = "Yugoslavia", Chickens = 567)
Using this minimal example, how do I create this dataframe?
data.frame(Country = c("Serbia", "Montenegro"), Chickens = 567)

Answer 1

you can do in one tidyverse pipe:
library(tidyverse)
df2 <- df %>%
mutate(Country = if_else(Country == "Yugoslavia", "Serbia", as.character(Country))) %>%
bind_rows(df) %>%
mutate(Country = if_else(Country == "Yugoslavia", "Montenegro", as.character(Country)))
You could also use mutate_if instead of the if_else statements.
Country Chickens
1 Serbia 567
2 Montenegro 567
By default data.frame turns character columns into factors. The substitution above coerces into character.
If you want to preserve the factor class then just add:
%>% mutate(Country = as.factor(Country))
... at the end.

Answer 2

You can do something like this:
data2<-data[data$country=="Yugoslavia"]
levels(data2$country)[levels(data2$country)=="Yugoslavia"]<-"Serbia"
levels(data$country)[levels(data$country)=="Yugoslavia"]<-"Montenegro"
rbind(data,data2)

Answer 3

You can write a function which returns the duplicated and renamed rows like:
fun <- function(y) {
if(y[["Country"]] == "Yugoslavia") rbind(replace(y, "Country", "Serbia")
, replace(y, "Country", "Montenegro"))
else y
}
do.call("rbind", apply(x, 1, fun))
# Country Chickens
#[1,] "Italy" " 2"
#[2,] "Serbia" "567"
#[3,] "Montenegro" "567"
#[4,] "Austria" " 3"
Or if order does not matter:
rbind(x[x$Country != "Yugoslavia",]
, replace(x[x$Country == "Yugoslavia",], "Country", "Serbia")
, replace(x[x$Country == "Yugoslavia",], "Country", "Montenegro"))
# Country Chickens
#1 Italy 2
#3 Austria 3
#2 Serbia 567
#21 Montenegro 567
Data:
x <- data.frame(Country = c("Italy","Yugoslavia","Austria"), Chickens = c(2,567,3))
x
# Country Chickens
#1 Italy 2
#2 Yugoslavia 567
#3 Austria 3