You can use one of the following methods to convert a categorical variable to a numeric variable in R:

**Method 1: Convert One Categorical Variable to Numeric**

df$var1 <- unclass(df$var1)

**Method 2: Convert Multiple Categorical Variables to Numeric**

df[, c('var1', 'var2')] <- sapply(df[, c('var1', 'var2')], unclass)

**Method 3: Convert All Categorical Variables to Numeric**

df[sapply(df, is.factor)] <- data.matrix(df[sapply(df, is.factor)])

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

#create data frame with some categorical variables df <- data.frame(team=as.factor(c('A', 'B', 'C', 'D')), conf=as.factor(c('AL', 'AL', 'NL', 'NL')), win=as.factor(c('Yes', 'No', 'No', 'Yes')), points=c(122, 98, 106, 115)) #view data frame df team conf win points 1 A AL Yes 122 2 B AL No 98 3 C NL No 106 4 D NL Yes 115

**Method 1: Convert One Categorical Variable to Numeric**

The following code shows how to convert one categorical variable in a data frame to a numeric variable:

#convert 'team' variable to numeric df$team <- unclass(df$team) #view updated data frame df team conf win points 1 1 AL Yes 122 2 2 AL No 98 3 3 NL No 106 4 4 NL Yes 115

Notice that the values for the ‘team’ variable have been converted to numeric values.

**Method 2: Convert Multiple Categorical Variables to Numeric**

The following code shows how to convert multiple categorical variables in a data frame to numeric variables:

#convert 'team' and 'win' variables to numeric df[, c('team', 'win')] <- sapply(df[, c('team', 'win')], unclass) #view updated data frame df team conf win points 1 1 AL 2 122 2 2 AL 1 98 3 3 NL 1 106 4 4 NL 2 115

Notice that the values for the ‘team’ and ‘win’ variables have been converted to numeric values.

**Method 3: Convert All Categorical Variables to Numeric**

The following code shows how to convert all categorical variables in a data frame to numeric variables:

#convert all categorical variables to numeric df[sapply(df, is.factor)] <- data.matrix(df[sapply(df, is.factor)]) #view updated data frame df team conf win points 1 1 1 2 122 2 2 1 1 98 3 3 2 1 106 4 4 2 2 115

Notice that the values for each of the categorical variables in the data frame have been converted to numeric values.

**Additional Resources**

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

How to Convert Date to Numeric in R

How to Convert Character to Factor in R

How to Convert Factor to Character in R