Sorry to edit this so much at this late stage, but the question and answers are confused so much by my incorrect use of terminology and the such, I feel that I should clear this up.
Where $a$ and $b$ are lists.
$a = \{\mathbf{true, false, true, false, false}\}$ $b = f(a) = \{0.8, 0, 0.8, 0, 0\}$
In this case each $\bf true$ in $a$ has become a $0.8$ in $b$, as with $\bf false$ and $0$.
What is $f$?