[Tutor] Python 2.7.1 interpreter complains about NameError: global name 'levenshtein_automata' is not defined
Good morning, I am using Python 2.7.1 on Windows XP Service Pack 3. Here
is the program where the Python interpreter complains about NameError:
global name 'levenshtein_automata' is not defined.
The python 2,7.1 error message is:
Traceback (most recent call last):
File "automata_test.py", line 174, in
length = len(list(testdfa.find_all_matches('food', 1, m)))
File "automata_test.py", line 145, in find_all_matches
lev = levenshtein_automata(word, k).to_dfa()
NameError: global name 'levenshtein_automata' is not defined
Here is the program. I have marked lines 174, 145 and 125.
import bisect
import random
class NFA(object):
EPSILON = object()
ANY = object()
def __init__(self, start_state):
self.transitions = {}
self.final_states = set()
self._start_state = start_state
@property
def start_state(self):
return frozenset(self._expand(set([self._start_state])))
def add_transition(self, src, input, dest):
self.transitions.setdefault(src, {}).setdefault(input, set()).add(dest)
def add_final_state(self, state):
self.final_states.add(state)
def is_final(self, states):
return self.final_states.intersection(states)
def _expand(self, states):
frontier = set(states)
while frontier:
state = frontier.pop()
new_states = self.transitions.get(state, {}).get(NFA.EPSILON,
set()).difference(states)
frontier.update(new_states)
states.update(new_states)
return states
def next_state(self, states, input):
dest_states = set()
for state in states:
state_transitions = self.transitions.get(state, {})
dest_states.update(state_transitions.get(input, []))
dest_states.update(state_transitions.get(NFA.ANY, []))
return frozenset(self._expand(dest_states))
def get_inputs(self, states):
inputs = set()
for state in states:
inputs.update(self.transitions.get(state, {}).keys())
return inputs
def to_dfa(self):
dfa = DFA(self.start_state)
frontier = [self.start_state]
seen = set()
while frontier:
current = frontier.pop()
inputs = self.get_inputs(current)
for input in inputs:
if input == NFA.EPSILON: continue
new_state = self.next_state(current, input)
if new_state not in seen:
frontier.append(new_state)
seen.add(new_state)
if self.is_final(new_state):
dfa.add_final_state(new_state)
if input == NFA.ANY:
dfa.set_default_transition(current, new_state)
else:
dfa.add_transition(current, input, new_state)
return dfa
class DFA(object):
def __init__(self, start_state):
self.start_state = start_state
self.transitions = {}
self.defaults = {}
self.final_states = set()
def add_transition(self, src, input, dest):
self.transitions.setdefault(src, {})[input] = dest
def set_default_transition(self, src, dest):
self.defaults[src] = dest
def add_final_state(self, state):
self.final_states.add(state)
def is_final(self, state):
return state in self.final_states
def next_state(self, src, input):
state_transitions = self.transitions.get(src, {})
return state_transitions.get(input, self.defaults.get(src, None))
def next_valid_string(self, input):
state = self.start_state
stack = []
# Evaluate the DFA as far as possible
print state
for i, x in enumerate(input):
print "%s" % input
print 'e'
stack.append((input[:i], state, x))
state = self.next_state(state, x)
if not state: break
else:
stack.append((input[:i+1], state, None))
if self.is_final(state):
# Input word is already valid
return input
# Perform a 'wall following' search for the lexicographically
smallest
# accepting state.
while stack:
path, state, x = stack.pop()
x = self.find_next_edge(state, x)
#print 'x'
if x:
path += x
state = self.next_state(state, x)
if self.is_final(state):
print 'p'
return path
stack.append((path, state, None))
print 'v'
return None
def find_next_edge(self, s, x):
if x is None:
x = '\0' # u'\0'
else:
x = chr(ord(x) + 1)
state_transitions = self.transitions.get(s, {})
if x in state_transitions or s in self.defaults:
return x
labels = sorted(state_transitions.keys())
pos = bisect.bisect_left(labels, x)
if pos < len(labels):
print 'n'
return labels[pos]
return None
def levenshtein_automata(self, term, k):# line 125 '
nfa = NFA((0, 0))
for i, c in enumerate(term):
for e in range(k + 1):
# Correct character
nfa.add_transition((i, e), c, (i + 1, e))
if e < k:
# Deletion
nfa.add_transition((i, e), NFA.ANY, (i, e + 1))
# Insertion
nfa.add_transition((i, e), NFA.EPSILON, (i + 1, e + 1))
# Substitution
nfa.add_transition((i, e), NFA.ANY, (i + 1, e + 1))
[Tutor] Python 2.7.1 interpreter passing function pointer as function argument and Shedskin 0.7
Good afternoon. I want to thank everyone who helped me fix the global
name 'levinshtein_automata' is not defined error.
When I run the Shedskin 0.7 Python to C+++ compiler on the
same python program, I receive the error message * Error *
automata_test.py:148 : unbound identifier 'lookup_func'. lookup_func is a
python function pointer passed as an argument to a python function.
I have marked lines 148,161,172 and 174 in the python program
automata_test.py shown below. The shedskin tutorial says the latest version
of the Shedskin 0.7 Python to C++ compiler does not support overloading
__iter__ and __call__. I was wondering if anyone could suggest a python
workaround to this error message as I am new to python. Thank you.
# automata_test.py
import bisect
import random
class NFA(object):
EPSILON = object()
ANY = object()
def __init__(self, start_state):
self.transitions = {}
self.final_states = set()
self._start_state = start_state
@property
def start_state(self):
return frozenset(self._expand(set([self._start_state])))
def add_transition(self, src, input, dest):
self.transitions.setdefault(src, {}).setdefault(input, set()).add(dest)
def add_final_state(self, state):
self.final_states.add(state)
def is_final(self, states):
return self.final_states.intersection(states)
def _expand(self, states):
frontier = set(states)
while frontier:
state = frontier.pop()
new_states = self.transitions.get(state, {}).get(NFA.EPSILON,
set()).difference(states)
frontier.update(new_states)
states.update(new_states)
return states
def next_state(self, states, input):
dest_states = set()
for state in states:
state_transitions = self.transitions.get(state, {})
dest_states.update(state_transitions.get(input, []))
dest_states.update(state_transitions.get(NFA.ANY, []))
return frozenset(self._expand(dest_states))
def get_inputs(self, states):
inputs = set()
for state in states:
inputs.update(self.transitions.get(state, {}).keys())
return inputs
def to_dfa(self):
dfa = DFA(self.start_state)
frontier = [self.start_state]
seen = set()
while frontier:
current = frontier.pop()
inputs = self.get_inputs(current)
for input in inputs:
if input == NFA.EPSILON: continue
new_state = self.next_state(current, input)
if new_state not in seen:
frontier.append(new_state)
seen.add(new_state)
if self.is_final(new_state):
dfa.add_final_state(new_state)
if input == NFA.ANY:
dfa.set_default_transition(current, new_state)
else:
dfa.add_transition(current, input, new_state)
return dfa
class DFA(object):
def __init__(self, start_state):
self.start_state = start_state
self.transitions = {}
self.defaults = {}
self.final_states = set()
def add_transition(self, src, input, dest):
self.transitions.setdefault(src, {})[input] = dest
def set_default_transition(self, src, dest):
self.defaults[src] = dest
def add_final_state(self, state):
self.final_states.add(state)
def is_final(self, state):
return state in self.final_states
def next_state(self, src, input):
state_transitions = self.transitions.get(src, {})
return state_transitions.get(input, self.defaults.get(src, None))
def next_valid_string(self, input):
state = self.start_state
stack = []
# Evaluate the DFA as far as possible
print state
for i, x in enumerate(input):
print "%s" % input
print 'e'
stack.append((input[:i], state, x))
state = self.next_state(state, x)
if not state: break
else:
stack.append((input[:i+1], state, None))
if self.is_final(state):
# Input word is already valid
return input
# Perform a 'wall following' search for the lexicographically
smallest
# accepting state.
while stack:
path, state, x = stack.pop()
x = self.find_next_edge(state, x)
#print 'x'
if x:
path += x
state = self.next_state(state, x)
if self.is_final(state):
print 'p'
return path
stack.append((path, state, None))
print 'v'
return None
def find_next_edge(self, s, x):
if x is None:
x = '\0'
else:
x = chr(ord(x) + 1)
state_transitions = self.transitions.get(s, {})
if x in state_transitions or s in self.defaults:
return x
labels = sorted(state_transitions.keys())
pos = bisect.bisect_left(labels, x)
if pos < len(labels):
print 'n'
return labels[pos]
return None
def levenshtein_automata(self, term, k):
print 's'
nfa = NFA((0, 0))
for i, c in enumerate(term):
for e in range(k + 1):
# Correct ch
Re: [Tutor] Python 2.7.1 interpreter passing function pointer as function argument and Shedskin 0.7
I asked the Shedskin developers about this issue and they are currently
adding support for __call__ . They recommend renaming the class Matcher
__call__ method ,for example as next, and then explicitly call it on line
148 as
lookup_func.next(match).
I followed their suggestion and the Shedskin 0.7 Python to C++ compiler
does not complain about the unbound identifier 'lookup_func' anymore.
I apologize for the cut and paste mangling. Is there a better method
than copy-pasting for including 20 or more lines of python source code in
the tutor posts? Thank you.
def find_all_matches(self, word, k, lookup_func):
lev = self.levenshtein_automata(word, k).to_dfa()
match = lev.next_valid_string('\0')
while match:
follow = lookup_func.test(match) ### line 148 ###
if not follow:
return
if match == follow:
yield match
follow = follow + '\0'
match = lev.next_valid_string(follow)
class Matcher(object):
def __init__(self, l):
self.l = l
self.probes = 0
def test(self, w):
self.probes += 1
pos = bisect.bisect_left(self.l, w)
if pos < len(self.l):
return self.l[pos]
else:
return None
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[Tutor] Python 2.7.1 interpreter question
I separated my test program into two python files. The first one is
automata.py. The pastebin url for automata.py is:
http://pastebin.com/embed_iframe.php?i=J9MRPibX";
style="border:none;width:100%">
The second file is automata_test2.py. It imports automata.py. The
pastebin url for automata_test2.py is:
http://pastebin.com/embed_iframe.php?i=A44d2EvV";
style="border:none;width:100%">.
When I use the Python 2.7.1 interpreter I get the following traceback
:
F:\shedskin\shedskin-0.7>python automata_test2.py
Traceback (most recent call last):
File "automata_test2.py", line 23, in
list(automata.find_all_matches('nice', 1, m))
AttributeError: 'module' object has no attribute 'find_all_matches'
Could anyone help me fix this error? I am new to python. Thank you.
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Re: [Tutor] Python 2.7.1 interpreter
I wanted to thank Steven D'Aprano and Allan Gauld for solving my Python 2.7.1 interpreter question in Tutor Digest Vol. 82 Issue 121. Thank you for yor help. ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
