def fromSeq(stateObjSeq):
''' returns a new Chain instance from given sequence of state objects
the probabilities of state transitions are set according to transition
frequencies in the given sequence
'''
(fromStateObjIter,toStateObjIter) = tee(stateObjSeq);
for _ in toStateObjIter:
break
nextStateObjsDict = dict()
for (fromStateObj,toStateObj) in zip(fromStateObjIter,toStateObjIter):
nextStateObjs = nextStateObjsDict.get(fromStateObj)
if nextStateObjs is None:
nextStateObjs = []
nextStateObjsDict[fromStateObj] = nextStateObjs
nextStateObjs.append(toStateObj)
nextStateNameAndObjs = list(nextStateObjsDict.items())
nextStateNameAndObjs.sort()
nextStateLeaPerState = tuple((stateObj,Alea.fromVals(*nextStateObjs)) for (stateObj,nextStateObjs) in nextStateNameAndObjs)
return Chain(nextStateLeaPerState)
