DescTools (version 0.99.19)

Recode: Recode a Factor

Description

Combining or rearranging a factor can be tedious if it has many levels. Recode supports this step by accepting a direct definition of newlevels by oldlevels as argument and adding an "elselevel" option.

Usage

Recode(x, ..., elselevel = NA, use.empty = FALSE)

Arguments

x

the factor whose levels are to be altered.

...

the old levels (combined by c() if there are several) named with the new level: newlevel_a=c("old_a", "old_b"), newlevel_b=c("old_c", "old_d"). See examples.

elselevel

the value for levels, which are not matched by newlevel's list. If this is set to NULL, the elselevels will be left unchanged. If set to NA (default) non matched levels will be set to NA.

use.empty

logical. Defines how a new level, which can't be found in x, should be handled. Should it be left in the level's list or be dropped? The default is FALSE, which drops empty levels.

Value

the factor having the new levels applied.

See Also

factor, levels There's another possible solution in the package car.

Examples

set.seed(1984)
x <- factor(sample(1:15, 20, replace=TRUE))
levels(x) <- paste("old", levels(x), sep="_")

y <- Recode(x,
            "new_1" = c("old_1","old_4","old_5"), 
            "new_2" = c("old_6","old_10","old_11"), 
            "new_3" = c("old_12","old_13"), 
            elselevel="other")

data.frame(x=x, y=y)



x <- factor(letters[1:6])

z1 <- Recode(x, AB=c("a","b"), CD=c("c","d"), elselevel="none of these")
z2 <- Recode(x, AB=c("a","b"), CD=c("c","d"), elselevel=NA)
z3 <- Recode(x, AB=c("a","b"), CD=c("c","d"), elselevel=NULL)
z4 <- Recode(x, AB=c("a","b"), GH=c("g","h"), elselevel=NA, use.empty=TRUE)
z5 <- Recode(x, AB=c("a","b"), GH=c("g","h"), elselevel=NA, use.empty=FALSE)

data.frame(z1, z2, z3, z4, z5)

lapply(data.frame(z1, z2, z3, z4, z5), levels)

# empty level GH exists in z4...
table(z4, useNA="ifany")
# and is dropped in z5
table(z5, useNA="ifany")