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Zahra Rajabi
pymdptoolbox
Commits
a76b938e
Commit
a76b938e
authored
Jan 21, 2013
by
Steven Cordwell
Browse files
added many comments
parent
5b516cdf
Changes
1
Show whitespace changes
Inline
Side-by-side
mdp.py
View file @
a76b938e
...
...
@@ -313,6 +313,16 @@ class MDP(object):
if
(
not
type
(
R
)
is
ndarray
):
raise
TypeError
(
mdperr
[
"R_type"
])
# NumPy has an array type of 'object', which is roughly equivalent to
# the MATLAB cell array. These are most useful for storing sparse
# matrices as these can only have two dimensions whereas we want to be
# able to store a transition matrix for each action. If the dytpe of
# the transition probability array is object then we store this as
# P_is_object = True.
# If it is an object array, then it should only have one dimension
# otherwise fail with a message expalining why.
# If it is a normal array then the number of dimensions must be exactly
# three, otherwise fail with a message explaining why.
if
(
P
.
dtype
==
object
):
if
(
P
.
ndim
>
1
):
raise
ValueError
(
mdperr
[
"obj_shape"
])
...
...
@@ -324,6 +334,8 @@ class MDP(object):
else
:
P_is_object
=
False
# As above but for the reward array. A difference is that the reward
# array can have either two or 3 dimensions.
if
(
R
.
dtype
==
object
):
if
(
R
.
ndim
>
1
):
raise
ValueError
(
mdperr
[
"obj_shape"
])
...
...
@@ -335,51 +347,100 @@ class MDP(object):
else
:
R_is_object
=
False
# We want to make sure that the transition probability array and the
# reward array are in agreement. This means that both should show that
# there are the same number of actions and the same number of states.
# Furthermore the probability of transition matrices must be SxS in
# shape, so we check for that also.
if
P_is_object
:
# If the user has put their transition matrices into a numpy array
# with dtype of 'object', then it is possible that they have made a
# mistake and not all of the matrices are of the same shape. So,
# here we record the number of actions and states that the first
# matrix in element zero of the object array says it has. After
# that we check that every other matrix also reports the same
# number of actions and states, otherwise fail with an error.
# aP: the number of actions in the transition array. This
# corresponds to the number of elements in the object array.
aP
=
P
.
shape
[
0
]
sP0
=
P
[
0
].
shape
[
0
]
sP1
=
P
[
0
].
shape
[
1
]
# check to see that the other object array elements are the same shape
# sP0: the number of states as reported by the number of rows of
# the transition matrix
# sP1: the number of states as reported by the number of columns of
# the transition matrix
sP0
,
sP1
=
P
[
0
].
shape
# Now we check to see that every element of the object array holds
# a matrix of the same shape, otherwise fail.
for
aa
in
range
(
1
,
aP
):
sP0aa
=
P
[
aa
].
shape
[
0
]
sP1aa
=
P
[
aa
].
shape
[
1
]
# sp0aa and sp1aa represents the number of states in each
# subsequent element of the object array. If it doesn't match
# what was found in the first element, then we need to fail
# telling the user what needs to be fixed.
sP0aa
,
sP1aa
=
P
[
aa
].
shape
if
((
sP0aa
!=
sP0
)
or
(
sP1aa
!=
sP1
)):
raise
ValueError
(
mdperr
[
"obj_square"
])
else
:
# if we are using a normal array for this, then the first
# dimension should be the number of actions, and the second and
# third should be the number of states
aP
,
sP0
,
sP1
=
P
.
shape
# the first dimension of the transition matrix must report the same
# number of states as the second dimension. If not then we are not
# dealing with a square matrix and it is not a valid transition
# probability. Also, if the number of actions is less than one, or the
# number of states is less than one, then it also is not a valid
# transition probability.
if
((
sP0
<
1
)
or
(
aP
<
1
)
or
(
sP0
!=
sP1
)):
raise
ValueError
(
mdperr
[
"P_shape"
])
# now we check that each transition matrix is square-stochastic. For
# object arrays this is the matrix held in each element, but for
# normal arrays this is a matrix formed by taking a slice of the array
for
aa
in
range
(
aP
):
if
P_is_object
:
self
.
checkSquareStochastic
(
P
[
aa
])
else
:
self
.
checkSquareStochastic
(
P
[
aa
,
:,
:])
aa
=
aa
+
1
#
aa = aa + 1
# why was this here?
if
R_is_object
:
# if the rewarad array has an object dtype, then we check that
# each element contains a matrix of the same shape as we did
# above with the transition array.
aR
=
R
.
shape
[
0
]
sR0
=
R
[
0
].
shape
[
0
]
sR1
=
R
[
0
].
shape
[
1
]
# check to see that the other object array elements are the same shape
sR0
,
sR1
=
R
[
0
].
shape
for
aa
in
range
(
1
,
aR
):
sR0aa
=
R
[
aa
].
shape
[
0
]
sR1aa
=
R
[
aa
].
shape
[
1
]
sR0aa
,
sR1aa
=
R
[
aa
].
shape
if
((
sR0aa
!=
sR0
)
or
(
sR1aa
!=
sR1
)):
raise
ValueError
(
mdperr
[
"obj_square"
])
elif
(
R
.
ndim
==
3
):
# This indicates that the reward matrices are constructed per
# transition, so that the first dimension is the actions and
# the second two dimensions are the states.
aR
,
sR0
,
sR1
=
R
.
shape
else
:
# then the reward matrix is per state, so the first dimension is
# the states and the second dimension is the actions.
sR0
,
aR
=
R
.
shape
# this is added just so that the next check doesn't error out
# saying that sR1 doesn't exist
sR1
=
sR0
# the number of actions must be more than zero, the number of states
# must also be more than 0, and the states must agree
if
((
sR0
<
1
)
or
(
aR
<
1
)
or
(
sR0
!=
sR1
)):
raise
ValueError
(
mdperr
[
"R_shape"
])
# now we check to see that what the transition array is reporting and
# what the reward arrar is reporting agree as to the number of actions
# and states. If not then fail explaining the situation
if
(
sP0
!=
sR0
)
or
(
aP
!=
aR
):
raise
ValueError
(
mdperr
[
"PR_incompat"
])
# We are at the end of the checks, so if no exceptions have been raised
# then that means there are (hopefullly) no errors and we return None
return
None
def
checkSquareStochastic
(
self
,
Z
):
"""Check if Z is a square stochastic matrix
...
...
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