Subsetting with character subscripts
Assigning names to vectors allow us to identify the subsets of vectors with the names. This is done technically with using a character value between the subsetting brackets [].
a <- 1:4
names(a) <- c("a", "b", "c", "d")
a["d"]
d
4
The returned value will be a named numeric vector (so the names are conserved).
Replacement with character subscripts
Similarly to numeric subscripts, the character subscripts can also be used to perform replacements:
g <- 1:4
names(g) <- c("a", "b", "c", "d")
g["d"] <- -9
a b c d
1 2 3 -9
Duplicates
If names are duplicated, and the duplicate name is queried, only the value that is present at the first occurrence of the queried value will be returned.
d <- 1:4
names(d) <- c("a", "b", "c", "a")
d["a"]
a
1
Replacement indicated the same way will also replace only the first value that occurrs at the queried character:
d <- 1:4
names(d) <- c("a", "b", "c", "a")
d["a"] <- -9
a b c a
-9 2 3 4