Consider the random Dirichlet partition of the interval into $n$ fragments at temperature $\theta >0.$ Using calculus for Dirichlet integrals, pre-asymptotic versions of the Ewens sampling formulae from finite Dirichlet partitions can be obtained. From these, straightforward proofs of the usual sampling formulae from random proportions with Poisson-Dirichlet PD$\left( \gamma \right) $ distribution can be supplied, while considering the Kingman limit $n\uparrow \infty $, $\theta \downarrow 0,$with $n\theta =\gamma >0$. In this manuscript, the Gibbs version of the Dirichlet partition with symmetric selection is considered. Using similar calculus for Dirichlet integrals, closed-form expressions of Ewens sampling formulae in the presence of selection are obtained; special types of Bell polynomials are shown to be involved.
