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Special Infix Operators

grapes.Rd

A series of useful infix operators, aka "grapes", that can be used to facilitate core functionality, test equality, perform set operations, etc.

Usage

x %@@% y

x %@@% y <- value

x %==% y

x %!=% y

x %===% y

x %set% y

x %!set% y

x %[[% y

Arguments

x

The left hand side of the infix operator.

y

The right hand side of the infix operator.

value

New value for attribute y.

Functions

  • x %@@% y: A friendly version of attr(x, y) to extract "@ribute" elements. y can be unquoted.

  • `%@@%`(x, y) <- value: Assign "@ributes" via infix operator. A friendly version of attr(x, y) <- value. y can be unquoted.

  • x %==% y: A gentler logical test for equality of two objects. Attributes are not checked. Use %===% to check attributes.

  • x %!=% y: A logical test that two objects are not equal.

  • x %===% y: Also tests attributes of x and y.

  • x %set% y: Subset values in x by y. Alias for x[x %in% y]. Similar to intersect(x, y) except names and class of x are maintained.

  • x %!set% y: Subset values in x not in y. Alias for x[!x %in% y]. Similar to setdiff(x, y) except names and class of x are maintained.

  • x %[[% y: Extracts the i^th element for each of n elements of a list or data frame, returning either a vector of length n or a single row data frame with n columns. More efficient alias for purrr::map_*(x, y).

See also

intersect(), setdiff(), all.equal(), isTRUE()

Examples

factor(1:3) %@@% levels
#> [1] "1" "2" "3"
factor(1:3, levels = LETTERS[1:3L]) %@@% levels
#> [1] "A" "B" "C"

mtcars %==% mtcars       # equal
#> [1] TRUE
cars2 <- mtcars
cars2 %@@% a <- "foo"  # attr assignment; with unquoted 'a'
mtcars %==% cars2        # attr not checked; TRUE
#> [1] TRUE
mtcars %===% cars2       # attr checked; FALSE
#> [1] FALSE

x <- list(a = "b", c = "d", e = "f")
x %set% c("a", "c", "d")   # 'c' match
#> $c
#> [1] "d"
#> 
x %!set% c("a", "c", "d")  # 'b' match
#> $a
#> [1] "b"
#> 
#> $e
#> [1] "f"
#> 
unlist(x) %!set% c("a", "c", "d")   # 'c' match; vector-vector
#>   a   e 
#> "b" "f" 

# extract elements of a list
x <- list(a = 1:3, b = 4:6, c = 7:9)
x %[[% 2L
#> a b c 
#> 2 5 8 

data.frame(x) %[[% 2L     # data frame -> same as x[2L, ]
#>   a b c
#> 2 2 5 8