fixest (version 0.5.1)

to_integer: 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.join = 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.join

Logical, or character, scalar, defaults to FALSE. Only used if multiple vectors are to be transformed into integers. If multi.join is not FALSE, the the values of the different vectors will be collated using paste with collapse=multi.join.

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.

Details

If multiple vectors have to be combined and add_items=TRUE, to have user readable values in the items, you should add the argument multi.join so that the values of the vectors are combined in a "user-readable" way. Note that in the latter case, the algorithm is much much slower.

Examples

# NOT RUN {
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
#

# by default, the two vector are fast combined, and items are meaningless
to_integer(x1, x2, add_items = TRUE)

# You can use multi.join to have human-readable values for the items:
to_integer(x1, x2, add_items = TRUE, multi.join = TRUE)

to_integer(x1, x2, add_items = TRUE, multi.join = "; ")

# }