A.4 기정의 상수 (Predefined Constant)

R에는 다음과 같은 상수들(contants)이 있다.

TRUE           # true,  1 as.numeric
FALSE          # false, 0 as.numeric
NULL           # no element
Inf            # +Infinity
-Inf           # -Infinity
NaN            # Not a Number
NA             # Not Available
NA_integer_    # integer type NA
NA_real_       # real type NA
NA_complex_    # complex type NA
NA_character_  # character type NA
LETTERS        # A to Z
letters        # a to z
month.abb      # Jan to Dec
month.name     # January to December
pi             # 3.14159...