Get continent name from country name in R - r

Question

I have a data frame with one column representing country names. My goal is to add one more column which gives the continent information. Please check the following use case:
my.df <- data.frame(country = c("Afghanistan","Algeria"))
Is there a package that I can use to append a column of data containing the continent names without having the original data?

Answer 1

You can use the countrycode package for this task.
library(countrycode)
df <- data.frame(country = c("Afghanistan",
"Algeria",
"USA",
"France",
"New Zealand",
"Fantasyland"))
df$continent <- countrycode(sourcevar = df[, "country"],
origin = "country.name",
destination = "continent")
#warning
#In countrycode(sourcevar = df[, "country"], origin = "country.name", :
# Some values were not matched unambiguously: Fantasyland
Result
df
# country continent
#1 Afghanistan Asia
#2 Algeria Africa
#3 USA Americas
#4 France Europe
#5 New Zealand Oceania
#6 Fantasyland <NA>

Answer 2

Expanding on Markus' answer, countrycode draws on codelists 'continent' declaration.
?codelist
Definition of continent:
continent: Continent as defined in the World Bank Development Indicators
The question asked for continents but sometimes continents don't provide enough groups for you to delineate the data. For example, continents groups North and South America into Americas.
What you might want is region:
region: Regions as defined in the World Bank Development Indicators
It is unclear how the World Bank groups regions but the below code shows how this destination is more granular.
library(countrycode)
egnations <- c("Afghanistan","Algeria","USA","France","New Zealand","Fantasyland")
countrycode(sourcevar = egnations, origin = "country.name",destination = "region")
Output:
[1] "Southern Asia"
[2] "Northern Africa"
[3] "Northern America"
[4] "Western Europe"
[5] "Australia and New Zealand"
[6] NA

Answer 3

You can try
my.df <- data.frame(country = c("Afghanistan","Algeria"),
continent= as.factor(c("Asia","Africa")))
merge(my.df, raster::ccodes()[,c("NAME", "CONTINENT")], by.x="country", by.y="NAME", all.x=T)
# country continent CONTINENT
# 1 Afghanistan Asia Asia
# 2 Algeria Africa Africa
Some country values might need an adjustment; I dunno since you did not provide all values.