在R中使用ifelse函数重新编码分类变量的级别

Question

I have to use the "ifelse" function in R to uncode values used in a variable.

The data frame being used is dance. The variable is Type. Via comments I have received, here is what I have:

ifelse(dance$Type=="Swg","Swing", 
ifelse(dance$Type=="Ldy","Lindy",
ifelse(dance$Type=="Blue","Blues",
else(dance$Type=="Contra","Contra"))))

I keep getting error messages. Are all of the commas correct? Also, did I end it correctly?

I keep getting error messages plus I'm supposed to specify the data frame I'm using somehow.

Any help would be greatly appreciated. Thank you.

Answer 1

If Type is a factor then you can rename the levels and extract them in this way (using f below):

f <- factor(c("Swg", "Ldy", "Blue", "Swg"))
# See the order of the levels by printing f. It's alphabetical
levels(f) <- c("Blues", "Lindy", "Swing")
as.character(f)

This will give

> f <- factor(c("Swg", "Ldy", "Blue", "Swg"))
> f
[1] Swg  Ldy  Blue Swg 
Levels: Blue Ldy Swg
> as.character(f)
[1] "Swg"  "Ldy"  "Blue" "Swg" 
> levels(f) <- c("Blues", "Lindy", "Swing")
> as.character(f)
[1] "Swing" "Lindy" "Blues" "Swing"

Answer 2

Thanks for your help. I figured it out via tips that were mentioned. I needed to name a dataframe and give an alternate solution for data not changed. I came up with:

Dance$new<-ifelse(dance$Type=="Swg","Swing", 
ifelse(dance$Type=="Ldy","Lindy",
ifelse(dance$Type=="Blue","Blues",
ifelse(dance$Type=="Contra","Contra",F))))