rec {misty}

Recode Variable

Description

This function recodes numeric vectors, character vectors, or factors according to recode specifications.

Usage

rec(..., data = NULL, spec, as.factor = FALSE, levels = NULL, append = TRUE,
    name = ".e", as.na = NULL, table = FALSE, check = TRUE)

Arguments

...

a numeric vector, character vector, factor, matrix or data frame. Alternatively, an expression indicating the variable names in data e.g., rec(x1, x2, x3, data = dat, spec = "1 = 0")). Note that the operators ., +, -, ~, :, ::, and ! can also be used to select variables, see 'Details' in the df.subset function.

data

a data frame when specifying one or more variables in the argument .... Note that the argument is NULL when specifying a a numeric vector, character vector, factor, matrix or data frame for the argument ....

spec

a character string of recode specifications (see 'Details').

as.factor

logical: if TRUE, character vector will be coerced to a factor.

levels

a character vector for specifying the levels in the returned factor.

as.na

a numeric vector indicating user-defined missing values, i.e. these values are converted to NA before conducting the analysis.

append

logical: if TRUE (default), centered variable(s) are appended to the data frame specified in the argument data.

name

a character string or character vector indicating the names of the recoded variables. By default, variables are named with the ending ".r" Resulting in e.g. "x1.r" and "x2.r". Variable names can also be specified using a character vector matching the number of variables specified in ... (e.g., name = c("recode.x1", "recode.x2")).

table

logical: if TRUE, a cross table variable x recoded variable is printed on the console if only one variable is specified in ....

check

logical: if TRUE (default), argument specification is checked.

Details

Recode specifications appear in a character string, separated by semicolons (see the examples below), of the form input = output. If an input value satisfies more than one specification, then the first (from left to right) applies. If no specification is satisfied, then the input value is carried over to the result. NA is allowed in input and output. Several recode specifications are supported:

Single Value

For example, spec = "0 = NA".

Vector of Values

For example, spec = "c(7, 8, 9) = 'high'".

Range of Values

For example, spec = "7:9 = 'C'". The special values lo (lowest value) and hi (highest value) may appear in a range. For example, spec = "lo:10 = 1". Note that : is not the R sequence operator. In addition you may not use : with the collect operator, e.g., spec = "c(1, 3, 5:7)" will cause an error.

else

For example, spec = "0 = 1; else = NA". Everything that does not fit a previous specification. Note that else matches all otherwise unspecified values on input, including NA.

Value

Returns a numeric vector or data frame with the same length or same number of rows as ... containing the recoded coded variable(s).

Note

This function was adapted from the recode() function in the car package by John Fox and Sanford Weisberg (2019).

Author(s)

Takuya Yanagida [e-mail]

References

Fox, J., & Weisberg S. (2019). An R Companion to Applied Regression (3rd ed.). Thousand Oaks CA: Sage. URL: https://socialsciences.mcmaster.ca/jfox/Books/Companion/

See Also

coding, item.reverse

Examples

#----------------------------------------------------------------------------
# Numeric vector
x.num <- c(1, 2, 4, 5, 6, 8, 12, 15, 19, 20)

# Example 1a: Recode 5 = 50 and 19 = 190
rec(x.num, spec = "5 = 50; 19 = 190")

# Example 1b: Recode 1, 2, and 5 = 100 and 4, 6, and 7 = 200 and else = 300
rec(x.num, spec = "c(1, 2, 5) = 100; c(4, 6, 7) = 200; else = 300")

# Example 1c: Recode lowest value to 10 = 100 and 11 to highest value = 200
rec(x.num, spec = "lo:10 = 100; 11:hi = 200")

# Example 1d: Recode 5 = 50 and 19 = 190 and check recoding
rec(x.num, spec = "5 = 50; 19 = 190", table = TRUE)

#----------------------------------------------------------------------------
# Character vector
x.chr <- c("a", "c", "f", "j", "k")

# Example 2a: Recode a to x
rec(x.chr, spec = "'a' = 'X'")

# Example 2b: Recode a and f to x, c and j to y, and else to z
rec(x.chr, spec = "c('a', 'f') = 'x'; c('c', 'j') = 'y'; else = 'z'")

# Example 2c: Recode a to x and coerce to a factor
rec(x.chr, spec = "'a' = 'X'", as.factor = TRUE)

#----------------------------------------------------------------------------
# Factor
x.fac <- factor(c("a", "b", "a", "c", "d", "d", "b", "b", "a"))

# Example 3a: Recode a to x, factor levels ordered alphabetically
rec(x.fac, spec = "'a' = 'x'")

# Example 3b: Recode a to x, user-defined factor levels
rec(x.fac, spec = "'a' = 'x'", levels = c("x", "b", "c", "d"))

#----------------------------------------------------------------------------
# Multiple variables
dat <- data.frame(x1.num = c(1, 2, 4, 5, 6),
                  x2.num = c(5, 19, 2, 6, 3),
                  x1.chr = c("a", "c", "f", "j", "k"),
                  x2.chr = c("b", "c", "a", "d", "k"),
                  x1.fac = factor(c("a", "b", "a", "c", "d")),
                  x2.fac = factor(c("b", "a", "d", "c", "e")))

# Example 4a: Recode numeric vector and attach to 'dat'
dat <- cbind(dat, rec(dat[, c("x1.num", "x2.num")], spec = "5 = 50; 19 = 190"))

# Example 4b: Alternative specification using the 'data' argument,
rec(x1.num, x2.num, data = dat, spec = "5 = 50; 19 = 190")

# Example 4c: Recode character vector and attach to 'dat'
dat <- cbind(dat, rec(dat[, c("x1.chr", "x2.chr")], spec = "'a' = 'X'"))

# Example 4d: Recode factor vector and attach to 'dat'
dat <- cbind(dat, rec(dat[, c("x1.fac", "x2.fac")], spec = "'a' = 'X'"))