A variable is any characteristic of a data unit that can be counted, measured or observed. Variables can be numeric or categorical Animation: Screen shows a three level flowchart. The top level is ...

Abstract: The optimal power flow (OPF) problem with discrete control variables is an NP-hard problem in its exact formulation. To cope with the immense computational-difficulty of this problem, we ...

How to arrange discrete variable along an axis How to arrange the keys in a legend How to arrange the panels of a facetted plot How to choose the appropriate colour scale for a categorical variable ...