Recode a Variable

Description

Recodes a numeric vector, character vector, or factor according to simple recode specifications. Recode is an alias for recode that avoids name clashes with packages, such as Hmisc, that have a recode function.

Usage

recode(var, recodes, as.factor.result, as.numeric.result=TRUE, levels)

Recode(...)

Arguments

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 on input and output. Several recode specifications are supported:

single value

For example, 0=NA.

vector of values

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

range of values

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

else

everything that does not fit a previous specification. For example, else=NA. Note that else matches all otherwise unspecified values on input, including NA.

If all of the output values are numeric, and if as.factor.result is FALSE, then a numeric result is returned; if var is a factor, then by default so is the result.

Value

a recoded vector of the same length as var.

Author(s)

John Fox jfox@mcmaster.ca

References

Fox, J. and Weisberg, S. (2011) An R Companion to Applied Regression, Second Edition, Sage.

See Also

cut, factor

Examples

x<-rep(1:3,3)
x
## [1] 1 2 3 1 2 3 1 2 3
recode(x, "c(1,2)='A'; 
	else='B'")
## [1] "A" "A" "B" "A" "A" "B" "A" "A" "B"
Recode(x, "1:2='A'; 3='B'")
## [1] "A" "A" "B" "A" "A" "B" "A" "A" "B"