Filter Content By
Version
Text Search
${sidebar_list_label} - Back
Filter by Language
Building a multi-dimensional array of variables
The next step in our example (after creating an empty Model
object) is to add decision variables to the model. The variables are created
using addVars
, and are returned in a tupledict
which
we'll call flow
:
# Create optimization model m = gp.Model('netflow') # Create variables flow = m.addVars(commodities, arcs, obj=cost, name="flow")
The first, positional arguments to addVars
give the index set.
In this case, we'll be indexing flow
by commodities
and
arcs
. In other words, flow[c,i,j]
will capture the flow
of commodity c
from node i
to node j
. Note that
flow
only contains variables for source, destination pairs
that are present in arcs
.
Note also that flow[c,i,j]
is a continuous decision variable;
variables are assumed to be continuous unless you state otherwise.