Convert a mapping to data.frame

Description

The resulting data.frame has 2 columns: mapsfrom, and mapsto.

Usage

## S3 method for class 'mapping'
as.data.frame(x, ...)

Arguments

Value

A data.frame.

Construct a factor from one or more vectors

Description

A factor is constructed from one or more atomic vectors. If more than one atomic vector is supplied, then a compound value is constructed by concatenating the values together. The order of the levels is the natural order in which the values appear.

Usage

cf(x, ..., sep = ";")

Arguments

Value

A factor.

Examples

x <- c("A", "B", "A")
y <- c(2, 5, 7)
cf(x, y)
mapping(cf(x, y), c("X", "Y", "Z"))

Mapping from continuous to categorical

Description

Mapping from continuous to categorical

Usage

cut_mapping(..., to = NULL, na = NA, ch.as.fact = TRUE)

Arguments

Value

A function that cuts a numeric vector and maps the result.

Examples

x <- c(0, 10, 20, 30, Inf)
m <- cut_mapping(x, right=FALSE,
    to=c("0 to <10", "10 to <20", "20 to <30", ">= 30"))
print(m)
m(c(5, 27, 3, 10, 99))

Domain and codomain of a mapping.

Description

Domain and codomain of a mapping.

Usage

domain(x)

codomain(x)

Arguments

Value

x A vector of the same type as we supplied when the mapping was created.

Note

These aren't the true domain and codomain in the mathematical sense; both can contain duplicates.

Examples

sex.mapping <- mapping(c("Female", "F", "Male", "M"), c(0, 0, 1, 1))
domain(sex.mapping)
codomain(sex.mapping)

Inverse of a mapping

Description

Given a mapping x, return the inverse mapping.

Usage

inverse(x)

Arguments

Value

The inverse mapping.

Examples

sex.mapping <- mapping(c("Female", "F", "Male", "M"), c(0, 0, 1, 1))
sex.inverse.mapping <- inverse(sex.mapping)
sex.inverse.mapping(c(0, 0, 1, 0))

Generate a Mapping Function

Description

This function returns a function that does a simple mapping from one set of value to another. It is a function-generating function.

Usage

mapping(from, to, na = NA, ch.as.fact = TRUE, unmapped = NA)

pmapping(..., unmapped = I)

Arguments

Details

This function returns a function. When called with a vector argument x, this function will return a vector y of the same length as x and such that each element y[i] is equal to to[j] where j is the smallest integer such that from[j] == x[i], and the value unmapped (or, if it's a function, unmapped(x[i])) if no such j exists.

pmapping() creates a partial mapping, which maps certain elements while preserving the rest (by making unmapped=I the default).

Note: from will always be matched as a string, even if it is numeric. So, mapping(1, "A") and mapping("1", "A") are the same, and both functions will return "A" when called with either 1 or "1".

Value

A function that translates from from to to. The function also has an inverse which is a function that performs the inverse mapping.

See Also

inverse(), codomain(), domain(), remap(), text2mapping(), cut_mapping()

Examples

sex.mapping <- mapping(c("Female", "F", "Male", "M"), c(0, 0, 1, 1))
sex.mapping(c("Female", "Female", "Male", "F"))

sex.mapping <- mapping(0:1, c("Female", "Male"), na="Unknown")
sex.mapping(c(0, 1, NA, 0, 1, 1, 0))
inverse(sex.mapping)(c("Female", "Male", "Unknown"))

from <- c(0, 1, NA)
to <- c(NA, "Male", "Female")
x <- c(0, 1, NA, 0, 1, 1, 0)
sex.mapping <- mapping(c(0, 1, NA), c(NA, "Male", "Female"))
sex.mapping
sex.mapping(c(0, 1, NA, 0, 1, 1, 0))
inverse(sex.mapping)
inverse(sex.mapping)(c("Female", "Male", NA))

race.mapping <- mapping(c(
      "1"="WHITE",
      "2"="BLACK OR AFRICAN AMERICAN",
      "5"="AMERICAN INDIAN OR ALASKA NATIVE"))
race.mapping(1:5)

# Use of `unmapped`
dv.mapping <- mapping("BQL", -99, unmapped=as.numeric)
dv.mapping(c("3.1", "BQL", "2.7", "100"))

# Map certain elements and preserves the rest
x <- LETTERS[1:5]
pmapping("B", "Z")(x)
mapping("B", "Z", unmapped=I)(x)  # Same

A mapping that adds a prefix and/or suffix

Description

A mapping that adds a prefix and/or suffix

Usage

paste_mapping(prefix = NULL, suffix = NULL)

Arguments

Value

A mapping function.

Examples

# The objective is to turn a numeric vector into a factor such that
# the levels preserve the numeric order but contain the suffix "mg"
# (i.e., so that 2 becomes "2 mg" for instance)
x <- c(1, 2, 1, 10, 3, 2, 2, 1)

# The following does not produce the levels in the desired numeric order
# (because alphabetical ordering places "10" before "2")
factor(paste(x, "mg"))

# The following works, but takes 2 lines of code and requires a variable
# assignment
y <- factor(x)
levels(y) <- paste(levels(y), "mg")
y

# This does the same thing with one line of code and no assignment
paste_mapping(, " mg")(x)

# -----

# In this example, you start with a factor, and want to preserve its ordering
x <- factor(c("Treatment", "Placebo"), levels=c("Treatment", "Placebo"))

# Again, this won't work as desired
factor(paste("Randomized to", x, "Group"))

# But this will
paste_mapping("Randomized to ", " Group")(x)

Print a mapping

Description

Print a mapping

Usage

## S3 method for class 'mapping'
print(x, ...)

Arguments

Value

Returns x invisibly.

Re-map a variable

Description

Apply a mapping to a vector directly. The mapping is temporary and not saved.

Usage

remap(x, ...)

Arguments

Value

The values returned by calling the mapping function.

Examples

x <- c("A", "B", "A")
remap(x, c(A=0, B=1))

Convenient shorthand for specifying mappings with text strings

Description

Convenient shorthand for specifying mappings with text strings

Usage

text2mapping(
  text,
  file = NULL,
  sep = "|",
  flip = FALSE,
  convert.na = TRUE,
  numericWherePossible = TRUE,
  ...
)

Arguments

Value

A mapping.

Examples

f <- text2mapping("
L | Low
M | Medium
H | High
")
f(warpbreaks$tension)