Chapter 5 Working with Factors

5.1 Manually recode/change a factor’s levels

Use forcats::fct_recode()

diamonds=diamonds %>% as_tibble()

diamonds$cut=fct_recode(diamonds$cut, "meh"="Fair", "Wow"="Premium")

summary(diamonds$cut)

##       meh      Good Very Good       Wow     Ideal 
##      1610      4906     12082     13791     21551

5.2 Collapse factor levels

Extremely useful command for when you have infrequent cases in one factor and need to combine it with another.

Works by specifying a series of new level names, each of which contains the information from the old variables. Format is as follows:

fct_collapse(dataset$variable,
            NewLevelA=c("OldLevel1","Oldlevel2"), # NewLevelA is the new variable that contains both variables 1 and 2
            NewLevelB=c("OldLevel3"))

5.3 Add levels to a factor

use fct_expand()

print("temp")

## [1] "temp"

5.4 Drop unused levels

Use fct_drop()

print("temp")

## [1] "temp"

5.5 Change the order of a factor’s levels

example_data=tribble(~person, ~condition,
                     "bob", "25 years",
                     "jane", "5 years",
                     "jim", "5 years",
                     "john", "25 years")

example_data$condition=factor(example_data$condition)

str(example_data$condition)

##  Factor w/ 2 levels "25 years","5 years": 1 2 2 1

Notice that R thinks these are nominal factors, and that 25 comes before 5. To fix this and correct the level order…

example_data$condition =fct_relevel(example_data$condition, c("5 years", "25 years")) # specify level order

str(example_data$condition)

##  Factor w/ 2 levels "5 years","25 years": 2 1 1 2