Operator
Arithmetic
10L + 66L # integer
2.0 * 2L # numeric
1 / 2
c(1,2,3)^2
# Remainder
3 %% 2 # 1 (numeric)
3L %% 2L # 1 (integer)
# Integer Division
5 %/% 2
5 == 2 * (5 %/% 2) + (5 %% 2) # TRUE
# Element-wise product
c(1,2,3) * c(3,2,1)
Note that
. There are special operators for matrix arithmetics.A %*% B
Comparison
1 > 2
2 <= 3
TRUE == TRUE
FALSE != FALSE
# Element-wise comparison
c(1,2,3) == c(1,2,4) # TRUE TRUE FALSE
c(1,2,3) == 1 # TRUE FALSE FALSE
# Identify if an element belongs to a vector.
1 %in% c(1,2,3)
- Use
near(x,y)to compare two floating point numbers.
Logic
TRUE | FALSE # or
TRUE || FALSE # or
TRUE & FALSE # and
TRUE && FALSE # and
!TRUE # not
# Element-wise logic operations
c(TRUE, FALSE, FALSE) | c(FALSE, TRUE, FALSE) # TRUE TRUE FALSE
Assignment
x <- 1
y = 1
z <<- 1
1 -> u
1 ->> w
cat(x, y, z, u, w)
- It's a convention to use
<-rather than=for assignment, and leave=only for function arguments. The reasons are compatibility and precedence (<-is slightly higher, and=is used for function arguments before the assignment)
The special assignment operators <<- and ->> are looking up operators, and can maintain states. They can assign value to the variables in the parent scopes. See the example
new_counter <- function() {
i <- 0
function() {
i <<- i + 1 # see if you change <<- to <-
i
}
}
counter_one <- new_counter() # outer function, with i = 0
counter_two <- new_counter()
counter_one() # call ther inner function, i is changed to 1
counter_one() # i is changed to 2, the state is maintained
counter_two()
Other
# Colon for sequence generating
all(1:4 == seq(1,4,1))
by zcysxy