substr(x, start, stop) substring(text, first, last = 1000000)
substr takes a character vector as an argument and
returns a vector whose elements contain the substring starting
with the character at position start up to the character
at position stop. If start is larger than the string
length then NA is returned. If stop is longer than start
and error is signalled.
substring is compatible with S. For vector arguments, it expands the
arguments cyclically.
paste, nchar, strsplit