Check column values are in different sets

Question

I have a data frame called data with lots of columns, and Country is one of them.

I created a new logical column called train, which is true when the row belongs to the train set and false otherwise. The data frame is already sampled.

Now I want to be sure that there are no countries in both train and test sets with this code:

nrow( data[ data[ data$train, ]$Country %in% data[! data$train, ]$Country, ] ) == 0

which evaluates to true, so I guess I sampled correctly. But that line makes my eyes bleed.

• Brian Diggs: As data is also the name of a function in the core utils package, it is not good practice to use it for the name of an object.

Answer 1

I would do:

with(data, length(intersect(Country[train], Country[!train])) == 0)