How to convert certain columns only to numeric?

Question

How can I convert certain columns only in a data frame to numeric?

For instance, I have this data frame:

structure(list(airport = c(         


        

Answer 1

The all.is.numeric function from the Hmisc package does a good job determining whether a given column can be cast to numeric.

Using this, you could do:

numeric_cols <- sapply(weatherDF, Hmisc::all.is.numeric)

if (sum(numeric_cols) > 1)  {
    weatherDF[,numeric_cols] <- data.matrix(weatherDF[,numeric_cols])
} else {
    weatherDF[,numeric_cols] <- as.numeric(weatherDF[,numeric_cols])
}