
40 R Programming for Bioinformatics
Map Map applies a function to the corresponding elements of an arbitrary
number of input vectors.
Negate Negate creates a negation of a given function.
Map is a lot like the apply family of functions (Section 8.2.2), and if named
arguments are given, where the names match the name of a formal argument
to the function being mapped, it is used.
> Map(paste, 1:4, letters[1:4], sep = "_")
[[1]]
[1] "1_a"
[[2]]
[1] "2_b"
[[3]]
[1] "3_c"
[[4]]
[1] "4_d"
Filter is also similar to the apply family of functions, with the distinction
that it filters out values that fail the predicate. A standard idiom for remov-
ing missing values from ...