fact2dummy {StatMatch}

Transforms a categorical variable in a set of dummy variables

Description

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

Usage

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).

Value

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

Author(s)

Marcello D'Orazio [e-mail]

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)