vctrs (version 0.6.5)

vec-set: Set operations

Description

• vec_set_intersect() returns all values in both x and y.

• vec_set_difference() returns all values in x but not y. Note that this is an asymmetric set difference, meaning it is not commutative.

• vec_set_union() returns all values in either x or y.

• vec_set_symmetric_difference() returns all values in either x or y but not both. This is a commutative difference.

Because these are set operations, these functions only return unique values from x and y, returned in the order they first appeared in the original input. Names of x and y are retained on the result, but names are always taken from x if the value appears in both inputs.

These functions work similarly to intersect(), setdiff(), and union(), but don't strip attributes and can be used with data frames.

Usage

vec_set_intersect(
  x,
  y,
  ...,
  ptype = NULL,
  x_arg = "x",
  y_arg = "y",
  error_call = current_env()
)
vec_set_difference(
  x,
  y,
  ...,
  ptype = NULL,
  x_arg = "x",
  y_arg = "y",
  error_call = current_env()
)
vec_set_union(
  x,
  y,
  ...,
  ptype = NULL,
  x_arg = "x",
  y_arg = "y",
  error_call = current_env()
)
vec_set_symmetric_difference(
  x,
  y,
  ...,
  ptype = NULL,
  x_arg = "x",
  y_arg = "y",
  error_call = current_env()
)

Value

A vector of the common type of x and y (or ptype, if supplied) containing the result of the corresponding set function.

Arguments

x, y

A pair of vectors.

...

These dots are for future extensions and must be empty.

ptype

If NULL, the default, the output type is determined by computing the common type between x and y. If supplied, both x and y will be cast to this type.

x_arg, y_arg

Argument names for x and y. These are used in error messages.

error_call

The execution environment of a currently running function, e.g. caller_env(). The function will be mentioned in error messages as the source of the error. See the call argument of abort() for more information.

Dependencies

vec_set_intersect()

• vec_proxy_equal()

• vec_slice()

• vec_ptype2()

• vec_cast()

vec_set_difference()

• vec_proxy_equal()

• vec_slice()

• vec_ptype2()

• vec_cast()

vec_set_union()

• vec_proxy_equal()

• vec_slice()

• vec_ptype2()

• vec_cast()

• vec_c()

vec_set_symmetric_difference()

• vec_proxy_equal()

• vec_slice()

• vec_ptype2()

• vec_cast()

• vec_c()

Details

Missing values are treated as equal to other missing values. For doubles and complexes, NaN are equal to other NaN, but not to NA.

Examples

x <- c(1, 2, 1, 4, 3)
y <- c(2, 5, 5, 1)

# All unique values in both `x` and `y`.
# Duplicates in `x` and `y` are always removed.
vec_set_intersect(x, y)

# All unique values in `x` but not `y`
vec_set_difference(x, y)

# All unique values in either `x` or `y`
vec_set_union(x, y)

# All unique values in either `x` or `y` but not both
vec_set_symmetric_difference(x, y)

# These functions can also be used with data frames
x <- data_frame(
  a = c(2, 3, 2, 2),
  b = c("j", "k", "j", "l")
)
y <- data_frame(
  a = c(1, 2, 2, 2, 3),
  b = c("j", "l", "j", "l", "j")
)

vec_set_intersect(x, y)
vec_set_difference(x, y)
vec_set_union(x, y)
vec_set_symmetric_difference(x, y)

# Vector names don't affect set membership, but if you'd like to force
# them to, you can transform the vector into a two column data frame
x <- c(a = 1, b = 2, c = 2, d = 3)
y <- c(c = 2, b = 1, a = 3, d = 3)

vec_set_intersect(x, y)

x <- data_frame(name = names(x), value = unname(x))
y <- data_frame(name = names(y), value = unname(y))

vec_set_intersect(x, y)