Boxplot of the 14 final features selected by a two-step feature selection that collectively made a significant contribution to zinc-binding residue prediction.

<p>Green and red boxes denote zinc-binding and non-zinc binding residues, respectively. The horizontal line in each box indicates the mean value of a corresponding feature. For each feature name in the x axis, po: positive samples (zinc-binding residues); ne: negative samples (non-binding residues).