Changing graph layout

[jarrod-dalton]

Here's a small issue that will improve visualization in certain types of networks. Can we add functionality to change the layout in plot.HydeNetwork()?

See this network for example:

g <- HydeNetwork(~ FarmersMarketReadiness | CommunityReadiness*PractitionerCapacity*SocioPoliticalContext
                 + CommunityReadiness|OrgCapacity*SocialCapital*Awareness*Logistics*Sustainability*Perceptions*Physical
                 + OrgCapacity|PractionerBudget*CommunityBudget*PractitionerHumanCap*CommunityHumanCap*Resources
                 + SocialCapital|AvailableNetworks*ConnectedToNetworks
                 + Awareness|RaisingAwareness*Advertising
                 + Logistics|Transportation*Cost
                 + Sustainability|PercievedSustainability*Ideas
                 + Perceptions|CommunityAwareness*CommunityPerception
                 + Physical|Access*AcceptablePlaces
                 + PractitionerCapacity|Experience*Exposure*CHC_Experience
                 + SocioPoliticalContext|Culture*CommunitySkills*TimeConstraints*HealthyLifestyle*LifestyleChanges*Tastes*HealthyFood
                 )
g <- setDecisionNodes(g, CommunityReadiness, PractitionerCapacity, SocioPoliticalContext)
g <- setUtilityNodes(g, FarmersMarketReadiness)
plot(g)

The DiagrammeR packages has options for specifying graph layout. See the section on GraphViz Engines in http://rich-iannone.github.io/DiagrammeR/graphviz.html. Below is a figure from that site: