fixed demo tests

nltk/__init__.py

@@ -100,7 +100,6 @@ from collocations import *
 from decorators import decorator, memoize
 from featstruct import *
 from grammar import *
-from olac import *
 from probability import *
 from text import *
 from tree import *

nltk/collocations.py

@@ -236,14 +236,14 @@ def demo(scorer=None, compare_scorer=None):
     if compare_scorer is None:
         compare_scorer = BigramAssocMeasures.raw_freq
 
-    from nltk import corpus
+    from nltk.corpus import stopwords, webtext
         
-    ignored_words = corpus.stopwords.words('english')
+    ignored_words = stopwords.words('english')
     word_filter = lambda w: len(w) < 3 or w.lower() in ignored_words
 
-    for file in corpus.webtext.files():
+    for file in webtext.fileids():
         words = [word.lower()
-                 for word in corpus.webtext.words(file)]
+                 for word in webtext.words(file)]
 
         cf = BigramCollocationFinder.from_words(words)
         cf.apply_freq_filter(3)

nltk/grammar.py

@@ -1323,10 +1323,6 @@ def cfg_demo():
     print `grammar.productions()`.replace(',', ',\n'+' '*25)
     print
     
-    print 'Coverage of input words by a grammar:'
-    print grammar.covers(['a','dog'])
-    print grammar.covers(['a','toy'])
-
 toy_pcfg1 = parse_pcfg("""
     S -> NP VP [1.0]
     NP -> Det N [0.5] | NP PP [0.25] | 'John' [0.1] | 'I' [0.15]
@@ -1391,10 +1387,6 @@ def pcfg_demo():
     print `grammar.productions()`.replace(',', ',\n'+' '*26)
     print
 
-    print 'Coverage of input words by a grammar:'
-    print grammar.covers(['a','boy'])
-    print grammar.covers(['a','girl'])
-
     # extract productions from three trees and induce the PCFG
     print "Induce PCFG grammar from treebank data:"
 

nltk/parse/sr.py

@@ -217,14 +217,14 @@ class ShiftReduceParser(ParserI):
             stack.  This is used with trace level 2 to print 'S'
             before shifted stacks and 'R' before reduced stacks.
         """
-        str = '  '+marker+' [ '
+        s = '  '+marker+' [ '
         for elt in stack:
             if isinstance(elt, Tree):
-                str += `Nonterminal(elt.node)` + ' '
+                s += `Nonterminal(elt.node)` + ' '
             else:
-                str += `elt` + ' '
-        str += '* ' + string.join(remaining_text) + ']'
-        print str
+                s += `elt` + ' '
+        s += '* ' + ' '.join(remaining_text) + ']'
+        print s
 
     def _trace_shift(self, stack, remaining_text):
         """

nltk/probability.py

@@ -280,6 +280,8 @@ class FreqDist(dict):
         :rtype: any or None
         """
         if self._max_cache is None:
+            if len(self) == 0:
+                raise ValueError('A FreqDist must have at least one sample before max is defined.')
             self._max_cache = max([(a,b) for (b,a) in self.items()])[1] 
         return self._max_cache