R Operator

Operator

Arithmetic

10L + 66L # integer
2.0 * 2L # numeric
1 / 2
c(1,2,3)^2
 
# Remainder
3  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

• The default arithmetics in R are element-wise, unlike MATLAB

Link to original

. 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))

• R Operator - Pipe