basic python questions

[nateastle]

I have a simple assignment for school but am unsure where to go. The
assignment is to read in a text file, split out the words and say which
line each word appears in alphabetical order. I have the basic outline
of the program done which is:

def Xref(filename):
try:
fp = open(filename, "r")
lines = fp.readlines()
fp.close()
except:
raise "Couldn't read input file \"%s\"" % filename
dict = {}
for line_num in xrange(len(line s)):
if lines[line_num] == "": continue
words = lines[line_num].split()
for word in words:
if not dict.has_key(wo rd):
dict[word] = []
if line_num+1 not in dict[word]:
dict[word].append(line_nu m+1)
return dict

My question is, how do I easily parse out punction marks and how do I
sort the list and if there anything else that I am doing wrong in this
code it would be much help.

[Paddy]

na*******@gmail .com wrote:

I have a simple assignment for school but am unsure where to go. The
assignment is to read in a text file, split out the words and say which
line each word appears in alphabetical order. I have the basic outline
of the program done which is:

def Xref(filename):
try:
fp = open(filename, "r")
lines = fp.readlines()
fp.close()
except:
raise "Couldn't read input file \"%s\"" % filename
dict = {}
for line_num in xrange(len(line s)):
if lines[line_num] == "": continue
words = lines[line_num].split()
for word in words:
if not dict.has_key(wo rd):
dict[word] = []
if line_num+1 not in dict[word]:
dict[word].append(line_nu m+1)
return dict

My question is, how do I easily parse out punction marks and how do I
sort the list and if there anything else that I am doing wrong in this
code it would be much help.

Hi,
on first reading, you have a naked except clause that catches all
exceptions. You might want to try your program on a non-existent file
to find out the actual exception you need to trap for that error
message. Do you want the program to continue if you have no input file?

If you have not covered Regular Expressions, often called RE's then one
way of getting rid of puctuation is to turn the problem on its head.
create a string of all the characters that you consider as valid in
words then go through each input line discarding any character not *in*
the string. Use the doctored line for word extraction.

help(sorted) will start you of on sorting in python. Other
documentation sources have a lot more.

P.S. I have not run the code myself
P.P.S. Where is the functions docstring!
P.P.P.S. You might want to read up on enumerate. It gives another way
to do things when you want an index as well as each item from an
iterable but remember, the index given starts from zero.

Oh, and welcome to comp.lang.pytho n :-)

- Paddy.

[Marc 'BlackJack' Rintsch]

In <11************ *********@j44g2 000cwa.googlegr oups.com>,
na*******@gmail .com wrote:

def Xref(filename):
try:
fp = open(filename, "r")
lines = fp.readlines()
fp.close()
except:
raise "Couldn't read input file \"%s\"" % filename
dict = {}
for line_num in xrange(len(line s)):

Instead of reading the file completely into a list you can iterate over
the (open) file object and the `enumerate()` function can be used to get
an index number for each line.

if lines[line_num] == "": continue

Take a look at the lines you've read and you'll see why the ``continue``
is never executed.

words = lines[line_num].split()
for word in words:
if not dict.has_key(wo rd):
dict[word] = []
if line_num+1 not in dict[word]:
dict[word].append(line_nu m+1)

Instead of dealing with words that appear more than once in a line you may
use a `set()` to remove duplicates before entering the loop.

Ciao,
Marc 'BlackJack' Rintsch

[Fredrik Lundh]

na*******@gmail .com wrote:

I have a simple assignment for school but am unsure where to go. The
assignment is to read in a text file, split out the words and say which
line each word appears in alphabetical order. I have the basic outline
of the program done which is:

looks like an excellent start to me.

def Xref(filename):
try:
fp = open(filename, "r")
lines = fp.readlines()
fp.close()
except:
raise "Couldn't read input file \"%s\"" % filename
dict = {}
for line_num in xrange(len(line s)):
if lines[line_num] == "": continue
words = lines[line_num].split()
for word in words:
if not dict.has_key(wo rd):
dict[word] = []
if line_num+1 not in dict[word]:
dict[word].append(line_nu m+1)
return dict

My question is, how do I easily parse out punction marks

it depends a bit how you define the term "word".

if you're using regular text, with a limited set of punctuation
characters, you can simply do e.g.

word = word.strip(".,! ?:;")
if not word:
continue

inside the "for word" loop. this won't handle such characters if they
appear inside words, but that's probably good enough for your task.

another, slightly more advanced approach is to use regular expressions,
such as re.findall("\w+ ") to get a list of all alphanumeric "words" in
the text. that'll have other drawbacks (e.g. it'll split up words like
"couldn't" and "cross-reference", unless you tweak the regexp), and is
probably overkill.

and how do I sort the list and

how to sort the dictionary when printing the cross-reference, you mean?
just use "sorted" on the dictionary; that'll get you a sorted list
of the keys.

sorted(dict)

to avoid duplicates and simplify sorting, you probably want to normalize
the case of the words you add to the dictionary, e.g. by converting all
words to lowercase.

if there anything else that I am doing wrong in this code

there's plenty of things that can be tweaked and tuned and written in a
slightly shorter way by an experienced Python programmer, but assuming
that this is a general programming assignment, I don't see something
seriously "wrong" in your code (just make sure you test it on a file
that doesn't exist before you hand it in)

</F>

[Paul McGuire]

<na*******@gmai l.comwrote in message
news:11******** *************@j 44g2000cwa.goog legroups.com...

>I have a simple assignment for school but am unsure where to go. The
assignment is to read in a text file, split out the words and say which
line each word appears in alphabetical order. I have the basic outline
of the program done which is:

And in general, this is one of the best "can anyone help me with my
homework?" posts I've ever seen.
A. You told us up front that it was your homework.
B. You made an honest stab at the solution before posting, and posted the
actual code.
C. You ended with some specific questions on things that didn't work or that
you wanted to improve.

Your current program looks like at least A- material. Add use of sorted and
enumerate, and handle that exception a little better, and you're getting
into A+ territory.

Out of curiosity, what school are you attending that is teaching Python, and
under what course of study?

-- Paul

[nateastle]

I am currently going to school at Utah Valley State College, the course
that I am taking is analysis of programming languages. It's an upper
division course but our teacher wanted to teach us python as part of
the course, he spent about 2 - 3 weeks on python which has been good. I
currently work with .net and it is fun to see what other languages have
and what sytax they use.

Paul McGuire wrote:

<na*******@gmai l.comwrote in message
news:11******** *************@j 44g2000cwa.goog legroups.com...

I have a simple assignment for school but am unsure where to go. The
assignment is to read in a text file, split out the words and say which
line each word appears in alphabetical order. I have the basic outline
of the program done which is:

And in general, this is one of the best "can anyone help me with my
homework?" posts I've ever seen.
A. You told us up front that it was your homework.
B. You made an honest stab at the solution before posting, and posted the
actual code.
C. You ended with some specific questions on things that didn't work or that
you wanted to improve.

Your current program looks like at least A- material. Add use of sorted and
enumerate, and handle that exception a little better, and you're getting
into A+ territory.

Out of curiosity, what school are you attending that is teaching Python, and
under what course of study?

-- Paul

[nateastle]

I have taken the coments and think I have implemented most. My only
question is how to use the enumerator. Here is what I did, I have tried
a couple of things but was unable to figure out how to get the line
number.

def Xref(filename):
try:
fp = open(filename, "r")
except:
raise "Couldn't read input file \"%s\"" % filename
dict = {}
line_num=0
for words in iter(fp.readlin e,""):
words = set(words.split ())
line_num = line_num+1
for word in words:
word = word.strip(".,! ?:;")
if not dict.has_key(wo rd):
dict[word] = []
dict[word].append(line_nu m)
fp.close()
keys = sorted(dict);
for key in keys:
print key," : ", dict[key]
return dict

Marc 'BlackJack' Rintsch wrote:

In <11************ *********@j44g2 000cwa.googlegr oups.com>,
na*******@gmail .com wrote:

def Xref(filename):
try:
fp = open(filename, "r")
lines = fp.readlines()
fp.close()
except:
raise "Couldn't read input file \"%s\"" % filename
dict = {}
for line_num in xrange(len(line s)):

Instead of reading the file completely into a list you can iterate over
the (open) file object and the `enumerate()` function can be used to get
an index number for each line.

if lines[line_num] == "": continue

Take a look at the lines you've read and you'll see why the ``continue``
is never executed.

words = lines[line_num].split()
for word in words:
if not dict.has_key(wo rd):
dict[word] = []
if line_num+1 not in dict[word]:
dict[word].append(line_nu m+1)

Instead of dealing with words that appear more than once in a line you may
use a `set()` to remove duplicates before entering the loop.

Ciao,
Marc 'BlackJack' Rintsch

[tom]

na*******@gmail .com wrote:

I have taken the coments and think I have implemented most. My only
question is how to use the enumerator. Here is what I did, I have tried
a couple of things but was unable to figure out how to get the line
number.

Try this in the interpreter,

l = [5,4,3,2,1]
for count, i in enumerate(l):
print count, i

def Xref(filename):
try:
fp = open(filename, "r")
except:
raise "Couldn't read input file \"%s\"" % filename
dict = {}
line_num=0
for words in iter(fp.readlin e,""):
words = set(words.split ())
line_num = line_num+1
for word in words:
word = word.strip(".,! ?:;")
if not dict.has_key(wo rd):
dict[word] = []
dict[word].append(line_nu m)
fp.close()
keys = sorted(dict);
for key in keys:
print key," : ", dict[key]
return dict

Marc 'BlackJack' Rintsch wrote:

>In <11************ *********@j44g2 000cwa.googlegr oups.com>,
na*******@gmail .com wrote:

>>def Xref(filename):
try:
fp = open(filename, "r")
lines = fp.readlines()
fp.close()
except:
raise "Couldn't read input file \"%s\"" % filename
dict = {}
for line_num in xrange(len(line s)):

Instead of reading the file completely into a list you can iterate over
the (open) file object and the `enumerate()` function can be used to get
an index number for each line.

>> if lines[line_num] == "": continue

Take a look at the lines you've read and you'll see why the ``continue``
is never executed.

>> words = lines[line_num].split()
for word in words:
if not dict.has_key(wo rd):
dict[word] = []
if line_num+1 not in dict[word]:
dict[word].append(line_nu m+1)

Instead of dealing with words that appear more than once in a line you may
use a `set()` to remove duplicates before entering the loop.

Ciao,
Marc 'BlackJack' Rintsch

[tom]

tom wrote:

na*******@gmail .com wrote:

>I have taken the coments and think I have implemented most. My only
question is how to use the enumerator. Here is what I did, I have tried
a couple of things but was unable to figure out how to get the line
number.

Try this in the interpreter,

l = [5,4,3,2,1]
for count, i in enumerate(l):
print count, i

you could do it like this.

for count, line in enumerate(fb):
for word in line.split():
etc...

filehandles are iterators themselves.

dont take my words for granted though, i'm kinda new to all this too :)

>def Xref(filename):
try:
fp = open(filename, "r")
except:
raise "Couldn't read input file \"%s\"" % filename
dict = {}
line_num=0
for words in iter(fp.readlin e,""):
words = set(words.split ())
line_num = line_num+1
for word in words:
word = word.strip(".,! ?:;")
if not dict.has_key(wo rd):
dict[word] = []
dict[word].append(line_nu m)
fp.close()
keys = sorted(dict);
for key in keys:
print key," : ", dict[key]
return dict

Marc 'BlackJack' Rintsch wrote:

>>In <11************ *********@j44g2 000cwa.googlegr oups.com>,
na*******@gmail .com wrote:

def Xref(filename):
try:
fp = open(filename, "r")
lines = fp.readlines()
fp.close()
except:
raise "Couldn't read input file \"%s\"" % filename
dict = {}
for line_num in xrange(len(line s)):
Instead of reading the file completely into a list you can iterate over
the (open) file object and the `enumerate()` function can be used to get
an index number for each line.

if lines[line_num] == "": continue
Take a look at the lines you've read and you'll see why the ``continue``
is never executed.

words = lines[line_num].split()
for word in words:
if not dict.has_key(wo rd):
dict[word] = []
if line_num+1 not in dict[word]:
dict[word].append(line_nu m+1)
Instead of dealing with words that appear more than once in a line you may
use a `set()` to remove duplicates before entering the loop.

Ciao,
Marc 'BlackJack' Rintsch

[Diez B. Roggisch]

na*******@gmail .com schrieb:

I have taken the coments and think I have implemented most. My only

Unfortunately, no.

question is how to use the enumerator. Here is what I did, I have tried
a couple of things but was unable to figure out how to get the line
number.

def Xref(filename):
try:
fp = open(filename, "r")
except:
raise "Couldn't read input file \"%s\"" % filename

You still got that I-catch-all-except in there.
This will produce subtle bugs when you e.g. misspell a variable name:

filename = '/tmp/foo'
try:
f = open(fliename, 'r')
except:
raise "can't open filename"
Please notice the wrong-spelled 'fliename'.

This OTOH will give you more clues on what really goes wrong:

filename = '/tmp/foo'
try:
f = open(fliename, 'r')
except IOError:
raise "can't open filename"
Diez