added state_from_transition, parameters and setparameters!!

Author: torfjelde

src/AbstractMCMC.jl

@@ -79,6 +79,36 @@ The `MCMCSerial` algorithm allows users to sample serially, with no thread or pr
 """
 struct MCMCSerial <: AbstractMCMCEnsemble end
 
+"""
+    state_from_transiton(state, transition_prev[, state_prev])
+
+Return new instance of `state` using information from `transition_prev` and, optionally, `state_prev`.
+
+Defaults to `setparameters!!(state, parameters(transition_prev))`.
+"""
+function state_from_transition(state, transition_prev, state_prev)
+    return state_from_transition(state, transition_prev)
+end
+
+function state_from_transition(state, transition)
+    return setparameters!!(state, parameters(transition))
+end
+
+"""
+    setparameters!!(state, parameters)
+
+Return new instance of `state` with parameters set to `parameters`.
+"""
+setparameters!!
+
+"""
+    parameters(transition)
+
+Return parameters in `transition`.
+"""
+parameters
+
+
 include("samplingstats.jl")
 include("logging.jl")
 include("interface.jl")