fact2dummy function

Transforms a categorical variable in a set of dummy variables

Transforms a factor or more factors contained in a data frame in a set of dummy variables, while numeric variables remain unchanged.

fact2dummy(data, all=TRUE, lab="x")

Arguments

• data: A factor or a data frame that contains one or more factors (columns whose class is factor or ordered ) that have to be substituted by the corresponding dummy variables.
• all: Logical. When all=TRUE (default) the output matrix will contain as many dummy variables as the number of the levels of the factor variable. On the contrary, when all=FALSE, the dummy variable related to the last level of the factor is dropped.
• lab: A character string with the name of the variable to be pasted with its levels. This is used only when data is a factor. By default it is set to x .

Details

This function substitutes categorical variables in the input data frame (columns whose class is factor or ordered ) with the corresponding dummy variables. Note that if a factor includes a missing values (NA) then all the associated dummies will report an NA in correspondence of the missing observation (row).

Returns

A matrix with the dummy variables instead of initial factor variables.

Author(s)

Marcello D'Orazio mdo.statmatch@gmail.com

See Also

gower.dist

Examples

x <- runif(5)
y <- factor(c(1,2,1,2,2))
z <- ordered(c(1,2,3,2,2))
xyz <- data.frame(x,y,z)
fact2dummy(xyz)

fact2dummy(xyz, all=FALSE)

#example with iris data frame
str(iris)
ir.mat <- fact2dummy(iris)
head(ir.mat)