def policyIter(gamma=0.5):
pi = initPolicy()
while True:
piOld = pi
#Solve system for V(s)
v = solveV(pi, gamma)
q = np.zeros((num_s, num_a))
for s in range(s_stop):
for a in range(num_a):
q[s, a] = gamma * np.dot(darts.transModel(s, a), v)
#Take the index of the maximum Q(s,a)
pi = np.argmax(q, 1)
#convergence condition
if np.array_equal(piOld, pi):
break
return pi
def policyIter(gamma=0.5):
pi = initPolicy()
while True:
piOld = pi
#Solve system for V(s)
v = solveV(pi, gamma)
q = np.zeros((num_s,num_a))
for s in range(s_stop):
for a in range(num_a):
q[s,a] = gamma * np.dot(darts.transModel(s,a), v)
#Take the index of the maximum Q(s,a)
pi = np.argmax(q, 1)
#convergence condition
if np.array_equal(piOld,pi):
break
return pi
def solveV(pi, gamma=0.5):
"Calculate the value of each state given the policies"
v = np.zeros(num_s)
#These are set because they end the game
v[101] = 1
v[102:num_s] = -1
vSub = np.zeros(s_stop + 1)
#These are subarrays of s and pi up to s_stop
sSub = np.arange(s_stop, dtype=float)
piSub = pi[:s_stop]
trans = darts.transModel(sSub, piSub)
a = trans[:, :s_stop] - np.identity(s_stop) / gamma
b = np.sum(trans[:, 102:117], 1) - trans[:, 101]
vSub = np.linalg.solve(a, b)
v[:s_stop] = vSub
return v
def solveV(pi, gamma=0.5):
"Calculate the value of each state given the policies"
v = np.zeros(num_s)
#These are set because they end the game
v[101] = 1
v[102:num_s] = -1
vSub = np.zeros(s_stop+1)
#These are subarrays of s and pi up to s_stop
sSub = np.arange(s_stop, dtype=float)
piSub = pi[:s_stop]
trans = darts.transModel(sSub, piSub)
a = trans[:,:s_stop] - np.identity(s_stop)/gamma
b = np.sum(trans[:,102:117],1) - trans[:,101]
vSub = np.linalg.solve(a,b)
v[:s_stop] = vSub
return v
