Question

I have a data frame like this:
df = data.frame(a=1:3, b=2:4, c=3:5)

I am selecting columns from that data frame using something akin to:
df[, c(T, F, T)]

This works fine as long as there are at least two columns to be returned; but, if I do this for example:
df[, c(T, F, F)]

… I suddenly only get a vector instead of a data.frame.

Normally this would be fine (or even desired), but since I need the result to be a data.frame at a later point, this completely messes up my scripts.

Is there a way I can prevent R from doing this automatic conversion to a vector for single-column selections?

Answer 1

This one is pretty simple. Append , drop = FALSE to your subsetting.

E.g.

df[, c(T, F, F), drop = FALSE]

Also works for matrices.