ChainScoreData

The purpose of the ChainScoreData object is reflected in its name: its purpose is to store data about the values of scores throughout the entire history of the Markov chain. You can think of it as containing an Array of Dict objects, where each element in the array is a Dict that corresponds to one state of the chain. In turn, each Dict contains keys for every AbstractScore passed to the chain by the user, and the values of the Dict are the values of the scoring functions, evaluated on a particular plan in the chain.

• GerryChain.get_score_values
• GerryChain.get_scores_at_step

get_scores_at_step()

get_scores_at_step(chain_data::ChainScoreData,
                   step::Int;
                   score_names::Array{String,1}=String[])::Dict{String, Any}

recom_chain or flip_chain returns a ChainScoreData object. If you want to know what the values of any/all scores were at a particular step in the chain, use get_scores_at_step. This will return a Dict{String, Any} from the name of the score to its value at step step. If no scores are passed in, all scores are returned by default. Here, step=0 represents the score of the original (initial) partition, so step=t will return the scores of the plan that was produced after taking t steps of the Markov chain.

Running get_scores_at_step() for different score types would get you different kinds of return values:

• Running get_scores_at_step(chain_data, step, "name_of_district_aggregate_score") would return an Array of length d, where d is the number of districts.
• Running get_scores_at_step(chain_data, step, "name_of_district_score") would return an Array of length d, where d is the number of districts.
• Running get_scores_at_step(chain_data, step, "name_of_plan_score") would return a single value, representing the value of the PlanScore for the plan at step step.

get_score_values()

get_score_values(chain_data::ChainScoreData,
                 score_name::String)

If you want to query the ChainScoreData for all values of a particular score throughout the history of the chain, use get_score_values. It will return an array of values where each element of the array corresponds to the value of the score at step i of the chain.