Recode a Factor
Combining or rearranging a factor can be tedious if it has many levels. Recode supports this step by
accepting a direct definition of new levels by enumerating old levelnames as argument and adding an "elselevel" option. If new levels are given as integer values they will be translated in the according levels.
Recode(x, ..., elselevel = NA, use.empty = FALSE, num = FALSE)
x |
the factor whose levels are to be altered. |
... |
the old levels (combined by |
elselevel |
the value for levels, which are not matched by newlevel list.
If this is set to |
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 |
num |
logical. If set to |
the factor having the new levels applied.
Andri Signorell <andri@signorell.net>
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")
# use integers to define the groups to collapse
set.seed(1972)
(likert <- factor(sample(1:10, size=15, replace=TRUE),
levels=1:10, labels=gettextf("(%s)", 1:10)))
Recode(likert, det=1:6, pas=7:8, pro=9:10)
# or directly turned to numeric
Recode(likert, "1"=1:6, "2"=7:8, "5"=9:10, num=TRUE)Please choose more modern alternatives, such as Google Chrome or Mozilla Firefox.