*93*

There are two methods you can use to convert a numeric variable to a factor variable in R:

**Method 1: Use as.factor()**

df$factor_variable factor(df$numeric_variable)

This will convert the numeric variable to a factor variable with the number of levels equal to the number of unique values in the original numeric variable.

**Method 2: Use cut()**

df$factor_variable 3, labels=c('lab1', 'lab2', 'lab3'))

This particular example will convert the numeric variable to a factor variable by “cutting” the numeric variable at 3 equally distanced values.

The following examples show how to use each method in practice with the following data frame in R:

#create data frame df frame(team=c('A', 'A', 'B', 'B', 'C', 'C', 'C', 'D'), points=c(12, 15, 22, 29, 35, 24, 11, 24)) #view data frame df team points 1 A 12 2 A 15 3 B 22 4 B 29 5 C 35 6 C 24 7 C 11 8 D 24 #view structure of data frame str(df) 'data.frame': 8 obs. of 2 variables: $ team : chr "A" "A" "B" "B" ... $ points: num 12 15 22 29 35 24 11 24

**Example 1: Convert Numeric to Factor Using as.factor()**

The following code shows how to use **as.factor()** to convert the **points** column from numeric to factor:

#convert points column from numeric to factor df$points factor(df$points) #view updated data frame df team points 1 A 12 2 A 15 3 B 22 4 B 29 5 C 35 6 C 24 7 C 11 8 D 24 #view updated structure of data frame str(df) 'data.frame': 8 obs. of 2 variables: $ team : chr "A" "A" "B" "B" ... $ points: Factor w/ 7 levels "11","12","15",..: 2 3 4 6 7 5 1 5

By using the str() function to view the structure of the data frame, we can see that the **points** column is now a factor with 7 different levels representing the 7 unique numeric values in the column.

**Example 2: Convert Numeric to Factor Using cut()**

The following code shows how to use **cut()** to convert the **points** column from a numeric variable to a factor variable with 3 levels:

#convert points column from numeric to factor with three levels df$points 3, labels=c('OK', 'Good', 'Great')) #view updated data frame df team points 1 A OK 2 A OK 3 B Good 4 B Great 5 C Great 6 C Good 7 C OK 8 D Good #view updated structure of data frame str(df) 'data.frame': 8 obs. of 2 variables: $ team : chr "A" "A" "B" "B" ... $ points: Factor w/ 3 levels "OK","Good","Great": 1 1 2 3 3 2 1 2

From the output we can see that the **points** variable has been converted from a numeric variable to a factor variable with three levels and the following labels:

- “OK”
- “Good”
- “Great”

Note that we chose to use three levels in this example, but feel free to cut the numeric variable into as many levels as you’d like by changing the **3** in the **cut()** function to another value.

**Additional Resources**

The following tutorials explain how to perform other common tasks in R:

How to Convert Numeric to Character in R

How to Convert Factor to Numeric in R

How to Convert Factor to Character in R