to_integer {fixest}

Fast transform of any type of vector(s) into an integer vector

Description

Tool to transform any type of vector, or even combination of vectors, into an integer vector ranging from 1 to the number of unique values. This actually creates an unique identifier vector.

Usage

to_integer(
  ...,
  sorted = FALSE,
  add_items = FALSE,
  items.list = FALSE,
  multi.df = FALSE,
  multi.join = "_",
  internal = FALSE
)

Arguments

...

Vectors of any type, to be transformed in integer.

sorted

Logical, default is FALSE. Whether the integer vector should make reference to sorted values?

add_items

Logical, default is FALSE. Whether to add the unique values of the original vector(s). If requested, an attribute items is created containing the values (alternatively, they can appear in a list if items.list=TRUE).

items.list

Logical, default is FALSE. Only used if add_items=TRUE. If TRUE, then a list of length 2 is returned with x the integer vector and items the vector of items.

multi.df

Logical, default is FALSE. If TRUE then a data.frame listing the unique elements is returned in the form of a data.frame. Ignored if add_items = FALSE.

multi.join

Character scalar used to join the items of multiple vectors. The default is "_". Ignored if add_items = FALSE.

internal

Logical, default is FALSE. For programming only. If this function is used within another function, setting internal = TRUE is needed to make the evaluation of ... valid. End users of to_integer should not care.

Value

Reruns a vector of the same length as the input vectors. If add_items=TRUE and items.list=TRUE, a list of two elements is returned: x being the integer vector and items being the unique values to which the values in x make reference.

Author(s)

Laurent Berge

Examples

x1 = iris$Species
x2 = as.integer(iris$Sepal.Length)

# transforms the species vector into integers
to_integer(x1)

# To obtain the "items":
to_integer(x1, add_items = TRUE)
# same but in list form
to_integer(x1, add_items = TRUE, items.list = TRUE)

# transforms x2 into an integer vector from 1 to 4
to_integer(x2, add_items = TRUE)

# To have the sorted items:
to_integer(x2, add_items = TRUE, sorted = TRUE)

# The result can safely be used as an index
res = to_integer(x2, add_items = TRUE, sorted = TRUE, items.list = TRUE)
all(res$items[res$x] == x2)


#
# Multiple vectors
#

to_integer(x1, x2, add_items = TRUE)

# You can use multi.join to handle the join of the items:
to_integer(x1, x2, add_items = TRUE, multi.join = "; ")