NAasLevel

Introduces NA as additional level for a factor or all factors in a data.frame. Missing values are recoded to the new level.

NAasLevel(X, except = NULL, NA_LEVEL = "NA")

Arguments

X	is either factorial variable or a data.frame
except	=NULL colnames of X (if data.frame) that should not be transformed
NA_LEVEL	="NA" defines the name of the NA level

Value

the transformed factor or data.frame

See also

droplevels

Examples

if (FALSE) {
# test NAasLevel      
df <- data.frame(
  x = factor(c("alpha","beta","alpha",NA), levels=c("alpha","beta","gamma")),
  y = c(5,8,2,1),
  z = factor(c("red","green","green",NA), levels=c("red","green","blue")),
  w = c("EGON","DETLEF","DETLEF","DETLEF")
)
df
NAasLevel(df$x)
NAasLevel(df$y)
NAasLevel(df$w)
NAasLevel(df)
NAasLevel(df,NA_LEVEL="missing") # other NA_LEVEL name
NAasLevel(df,except="z")         # z remains unchanged
}