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R Factors
Factors
Factors are used to categorize data. Examples of factors are:
- Demography: Male/Female
- Music: Rock, Pop, Classic, Jazz
- Training: Strength, Stamina
To create an element, use the factor() function and add a vector as an argument:
Example
levels(music_genre)
Result
[1] "Classic" "Jazz" "Pop" "Rock"
You can see from the example above that the feature has four levels (categories): Classic, Jazz, Pop and Rock.
To print only levels, use the levels() function:
Example
levels(music_genre)
Result
[1] "Classic" "Jazz" "Pop" "Rock" "Other"
You can also set levels, by adding a levels conflict within the function factor():
Example
length(music_genre)
Result
[1] 8
Factor Length
Use the length() function to find out how many items are in feature:
Example
length(music_genre)
Result
[1] 8
Access Factors
To access items for an item, see the reference number, using [] brackets:
Example
music_genre[3]
Result
[1] Classic Levels: Classic Jazz Pop Rock
Change Item Value
To change the value of an item, see the reference number:
Example
Change the value of the third item:
music_genre[3] <- "Pop"
music_genre[3]
Result
[1] Pop
Levels: Classic Jazz Pop Rock
Note that you cannot change the value of an item if it is not specified in the toolbar. The following example will illustrate an error:
Example
Trying to change the value of the third item ("Classic") to an item that does not exist/not predefined ("Opera"):
music_genre[3] <- "Opera"
music_genre[3]
Result
Warning message:
In `[<-.factor`(`*tmp*`, 3, value = "Opera") :
invalid factor level, NA generated
However, if you have already specified it within the Level Conflict, it will apply:
Example
Change the value if the third item:
music_genre[3] <- "Opera"
music_genre[3]
Result
[1] Opera
Levels: Classic Jazz Pop Rock Opera