[Tutor] Question on a example in the book "Learn to program using
python" by Alan Gauld
Klas Marteleur
klas.martelleur at telia.com
Mon Aug 2 16:34:18 CEST 2004
Thanks Kent and Alan for your hints
I have the problem that i get totaly blind when i look at code try to spot
errors, but i guess i will be better at it with more experience.
Taking out try / except was a good hint!
After i spoted some more errors i got the program to run, but i dont get
the punctuation count to work. I get "zero" on every row.
Shouldnt there be a "...D = TextDocument(sys.argv[1])... " somewere?
OT...and Alan you should not be sorry for the small errors in your book,
its the best "computer book" i have ever read i can see there is a lot of
work put into it!
I especially like that its possible to read the book and not sitting by the
computer at the same time, and its real packed with facts. Thanks! OT
Here is the "new" program:
----------------------------------------------------------------
#!/usr/bin/python
import sys,string, re
class Document:
def __init__(self, filename):
self.filename = filename
self.para_count = 1
self.line_count, self.sentence_count = 0,0
self.clause_count, self.word_count = 0,0
self.alphas = string.letters + string.digits
self.stop_tokens = ['.','?','!']
self.punctuation_chars = ['&','(',')','-',';',':',','] +
self.stop_tokens
self.punctuation_counts = {}
self.groups = []
for c in self.punctuation_chars:
self.punctuation_counts[c] = 0
self.format = """%s contains: %d paragraphs, %d lines and %d
sentences.These in turn contain %d clauses and a total of %d words."""
def getCharGroups(self):
try:
f = open(self.filename,"r")
for line in f.readlines():
self.line_count = self.line_count + 1
if len(line) == 1:
self.para_count = self.para_count + 1
else:
self.groups = self.groups + string.split(line)
except:
print "Failed to read file", self.filename
sys.exit()
def getWords(self):
for i in range(len(self.groups)):
self.groups[i] = self.ltrim(self.groups[i])
self.groups[i] = self.rtrim(self.groups[i])
self.removeExceptions()
def removeExceptions(self):
pass
def ltrim(self,word):
return word
def rtrim(self,word):
return word
def generateStats(self):
self.word_count = len(self.groups)
for c in self.stop_tokens:
self.sentence_count = self.sentence_count +
self.punctuation_counts[c]
for c in self.punctuation_counts.keys():
self.clause_count = self.clause_count +
self.punctuation_counts[c]
def printStats(self):
print self.format % (self.filename, self.para_count,
self.line_count, self.sentence_count, self.clause_count, self.word_count)
print "The following punctuation characters were used:"
for i in self.punctuation_counts.keys():
print "\t%s\t:\t%4d" % \
(i,self.punctuation_counts[i])
def Analyze(self):
self.getCharGroups()
self.getWords()
self.generateStats()
class TextDocument(Document):
def ltrim(self, word):
while (len(word) > 0) and (word[0] not in self.alphas):
ch = word[0]
if ch in self.punctuation_counts.keys():
self.punctuation_counts[ch] = self.punctuation_counts[ch]+1
word = word[1:]
return word
def rtrim(self,word):
while (len(word) > 0) and (word[-1] not in self.alphas):
ch = word[-1]
if ch in self.punctuation_counts.keys():
self.punctuation_counts[ch] = self.punctuation_counts[ch]+1
word = word[:-1]
return word
def removeExceptions(self):
top = len(self.groups)
i = 0
while i < top:
if (len(self.groups[i]) == 0):
del(self.groups[i])
top = top - 1
i = i + 1
class HTMLDocument(Document):
def getCharGroups(self):
tag = re.compile("<.+?>")
para = re.compile("<[pP]>")
self.para_count = 0
f = open(self.filename, "r")
lines = f.readlines()
n = 0
while n < len(lines):
if len(lines[n]) > 1:
if para.search(lines[n]):
self.para_count = self.para_count + 1
lines[n] = tag.sub('',lines[n])
if len(lines[n]) <= 1:
del(lines)[n]
else:
self.groups = self.groups + string.split(lines[n])
n = n + 1
else:
n = n + 1
self.line_count = len(lines)
if __name__ == "__main__":
if len (sys.argv) <> 2:
print "Usage: python document.py"
sys.exit()
else:
try:
D = TextDocument(sys.argv[1]) #This way it counts the
punctuation as well
# D = HTMLDocument(sys.argv[1])
D.Analyze()
D.printStats()
except:
print "Error analyzing file: %s" % sys.argv[1]
-------------------------------------------------------
Kind regards
Klas
söndagen den 1 augusti 2004 17.27 skrev Kent Johnson:
> Klas,
>
> The try / except block in your main program is hiding a lot of useful
> information from you - the details of what type of exception was thrown,
> and where the problem occurs. If a Python program exits by throwing an
> exception, the Python runtime prints this information. By catching the
> exception you are losing this information.
>
> Taking out the try / except, the main program looks like this:
> if __name__ == "__main__":
> if len (sys.argv) <> 2:
> print "Usage: python document.py"
> sys.exit()
> else:
> D = HTMLDocument(sys.argv[1])
> D.Analyze()
> D.printStats()
>
> If I run the program now, it outputs
> Traceback (most recent call last):
> File "document.py", line 130, in ?
> D.Analyze()
> File "document.py", line 70, in Analyze
> self.generateStats()
> File "document.py", line 54, in generateStats
> sentence_count = sentence_count + \
> UnboundLocalError: local variable 'sentence_count' referenced before
> assignment
>
> This is much more useful. Apparently the variable sentence_count is being
> used before it is initialized. The problem is at line 54, which reads
> sentence_count = sentence_count + \
> self.punctuation_counts[c]
>
> sentence_count is an instance variable and you have forgotten the self
> qualifier. These lines should read
> self.sentence_count = self.sentence_count + \
> self.punctuation_counts[c]
>
> Fixing this gets past the original error. There are several similar errors
> that I will let you find :-)
>
> Kent
>
> At 05:10 PM 8/1/2004 +0200, Klas Marteleur wrote:
> >Hi
> >
> >First of all thanks for a interesting mailing list, i think i learn a lot
> > by reading all good questions and answers.
> >
> >I bought a copy of the great book "Learn o program using python" 2001, i
> > have read it back and forth a couple of times and now i am going thru
> > testing and trying to understand all examples (...i think i am slowly
> > starting to learn
> >
> >:) )
> >
> >I got stuck on the case studie for the very useful :) program "Grammar
> >counter" though.
> >No matter what i try i get the error "Error analyzing file....."
> >
> >I type "python document.py example_file.txt" in a console.
> >
> >Can somebody of you professionals point me to what i am doing wrong?
> >
> >Many thanks
> >Klas Marteleur
>
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