Question

Here’s the code I use to find numeric variables in a data frame:

Data <- iris
numericvars <- NULL
for (Var in names(Data)) {
    if(class(Data[,Var]) == 'integer' | class(Data[,Var]) == 'numeric') {
        numericvars <- c(numericvars,Var)
    }
}
numericvars

Is there a less loopy way to do this?

Answer 1

This is a pretty simple one-liner with sapply:

sapply(Data, is.numeric)
# Sepal.Length  Sepal.Width Petal.Length  Petal.Width      Species 
#         TRUE         TRUE         TRUE         TRUE        FALSE

# is.numeric should pick up integer columns too
Data$Species <- as.integer(Data$Species)
sapply(Data, is.numeric)
# Sepal.Length  Sepal.Width Petal.Length  Petal.Width      Species 
#         TRUE         TRUE         TRUE         TRUE         TRUE