car (version 3.0-11)

recode: Recode a Variable


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.


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




numeric vector, character vector, or factor.


character string of recode specifications: see below.


return a factor; default is TRUE if var is a factor, FALSE otherwise.


if TRUE (the default), and as.factor is FALSE, then the result will be coerced to numeric if all values in the result are numerals---i.e., represent numbers.


an optional argument specifying the order of the levels in the returned factor; the default is to use the sort order of the level names.


arguments to be passed to recode.


a recoded vector of the same length as var.


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 c function within a recode specification, so for example c(1, 3, 5:7) will cause an error.


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

Character data and factor levels on the left-hand side of a recode specification must be quoted. Thus, e.g., c(a, b, c) = 'low' is not allowed, and should be c('a', 'b', 'c') = 'low'. Similarly, the colon is reserved for numeric data, and, e.g., c('a':'c') = 'low' is not allowed. If the var argument is a character variable with (some) values that are composed of numerals, or a factor with (some) levels that are numerals (e.g., '12' or '-2'), then these too must be quoted and cannot be used with colons (e.g., '15':'19' = '15 to 19' is not allowed, and could be specified as c('15', '16', '17', '18', '19') = '15 to 19', assuming that all values are the character representation of whole numbers).

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


Fox, J. and Weisberg, S. (2019) An R Companion to Applied Regression, Third Edition, Sage.

See Also

cut, factor


## [1] 1 2 3 1 2 3 1 2 3
recode(x, "c(1,2)='A'; 
## [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"
# }