list manipulation

20 New Member

Hi there,

I am having some trouble with list manipulation and was hoping someone could help me.

I have no problem reading in a text file as a list using filename.readli nes(). However, I am having some trouble with searching through this list to display the elements that I want.

I have a text file with this general format:

***************
text text text text
text text text text
text text text text
text text text text
***************
text text text text
text text text text
***************
text text text text
text text text text
text text text text
text text text text
text text text text
text text text text
text text text text
***************

etc. and what I'm having trouble trying to do is:
1) group together the text sections which are in between the astericks, so as to make separate 'records' (in a sense...)
2) if I want to search for a certain word within aforementioned 'records', I want to display the entire 'record' in which the search word is inside of (and this search word can be inside 1 or more 'records')

No matter what combination of loops I try, I am unsuccessful. Either the first line of the file prints out for ever, or my code isn't able to print anything out at all.

Please help!

Mar 27 '07 #1

Subscribe Reply

2757

bvdet

2,851

Recognized Expert Moderator Specialist

Hi there,

I am having some trouble with list manipulation and was hoping someone could help me.

I have no problem reading in a text file as a list using filename.readli nes(). However, I am having some trouble with searching through this list to display the elements that I want.

I have a text file with this general format:

***************
text text text text
text text text text
text text text text
text text text text
***************
text text text text
text text text text
***************
text text text text
text text text text
text text text text
text text text text
text text text text
text text text text
text text text text
***************

etc. and what I'm having trouble trying to do is:
1) group together the text sections which are in between the astericks, so as to make separate 'records' (in a sense...)
2) if I want to search for a certain word within aforementioned 'records', I want to display the entire 'record' in which the search word is inside of (and this search word can be inside 1 or more 'records')

No matter what combination of loops I try, I am unsuccessful. Either the first line of the file prints out for ever, or my code isn't able to print anything out at all.

Please help!

This piece of code will get you started:

Expand|Select|Wrap|Line Numbers

fList = [x.strip().split() for x in open('your_file').readlines()]

You now have a list of all lines split into words and stripped of newlines.

Initialize an output list.
Iterate through the list 'fList'.
If the keyword is 'in' the item, append the item to the output list.
If encapsulated in a function, return the output list.

HTH :)

Mar 27 '07 #2

ghostdog74

511

Recognized Expert Contributor

using this sample input you provided: say you want to search for "word"

Expand|Select|Wrap|Line Numbers

 
***************

text text text text

text text text text

text text text text

text text text text

***************

text word text text

text text text text

***************

text text text text

text text text text

text text text text

text text text text

text text text text

text text text text

text text text text

***************

Assuming the number of asterix remain constant.

Expand|Select|Wrap|Line Numbers

 
>>> data = open("file").read().split("***************")

>>> data

['', '\ntext text text text\ntext text text text\ntext text text text\ntext text text text\n', '\ntext word text text\ntext text text text\n', '\ntext text text text\ntext text text text\ntext text text text\ntext text text text\ntext text text text\ntext text text text\ntext text text text\n', '']

>>> for items in  data:

...  if "word" in items:

...   print ''.join(items) #print block where "word" is found

...
 
text word text text

text text text text

Mar 27 '07 #3

bartonc

6,596

Recognized Expert Expert

Hi there,

I am having some trouble with list manipulation and was hoping someone could help me.

I have no problem reading in a text file as a list using filename.readli nes(). However, I am having some trouble with searching through this list to display the elements that I want.

I have a text file with this general format:

***************
text text text text
text text text text
text text text text
text text text text
***************
text text text text
text text text text
***************
text text text text
text text text text
text text text text
text text text text
text text text text
text text text text
text text text text
***************

etc. and what I'm having trouble trying to do is:
1) group together the text sections which are in between the astericks, so as to make separate 'records' (in a sense...)
2) if I want to search for a certain word within aforementioned 'records', I want to display the entire 'record' in which the search word is inside of (and this search word can be inside 1 or more 'records')

No matter what combination of loops I try, I am unsuccessful. Either the first line of the file prints out for ever, or my code isn't able to print anything out at all.

Please help!

This is certainly a job for regular expressions. Regular exressions (the re module on Python) are a very under utilized tool. This is probably due to their quirky syntax and terse nature. I don't have the skills (yet) to help at this moment, but I an exited to tear into my new copy of Masering Regular Expressions very soon. There are some web site tutorials to get you started.

Basically, you write an expression that says "give me all the text between *** and *** that also has the searched for word(s), and the re module returns all that text. It is very worthwhile to (at least) experiment with. Have fun!

Mar 27 '07 #4

bvdet

2,851

Recognized Expert Moderator Specialist

using this sample input you provided: say you want to search for "word"

Expand|Select|Wrap|Line Numbers

***************

text text text text

text text text text

text text text text

text text text text

***************

text word text text

text text text text

***************

text text text text

text text text text

text text text text

text text text text

text text text text

text text text text

text text text text

***************

Assuming the number of asterix remain constant.

Expand|Select|Wrap|Line Numbers

>>> data = open("file").read().split("***************")

>>> data

['', '\ntext text text text\ntext text text text\ntext text text text\ntext text text text\n', '\ntext word text text\ntext text text text\n', '\ntext text text text\ntext text text text\ntext text text text\ntext text text text\ntext text text text\ntext text text text\ntext text text text\n', '']

>>> for items in  data:

...  if "word" in items:

...   print ''.join(items) #print block where "word" is found

...

text word text text

text text text text

Oops - I misread OP that a record is in between asterisks instead of each line. This is basically the same as ghostdog74's post:

Expand|Select|Wrap|Line Numbers

 import re
 
def get_records(fn,key):

    fList = [i for i in re.split(r'\*', open(fn).read()) if i != '']

    records = []

    for item in fList:

        if key in item:

            # to get rid of newlines

            # records.append(' '.join(item.strip().split('\n')))

            records.append(item)

    return records   
 
fn = 'your_file'

key = 'word'

records =  get_records(fn, key)

for record in records:

    print record

>>>
text word text text
text text text text

Mar 27 '07 #5

PNY

New Member

Thanks so much everyone! My code is working!!! Thanks so much for all your help!! :D

Oops - I misread OP that a record is in between asterisks instead of each line. This is basically the same as ghostdog74's post:

Expand|Select|Wrap|Line Numbers

import re

def get_records(fn,key):

    fList = [i for i in re.split(r'\*', open(fn).read()) if i != '']

    records = []

    for item in fList:

        if key in item:

            # to get rid of newlines

            # records.append(' '.join(item.strip().split('\n')))

            records.append(item)

    return records

fn = 'your_file'

key = 'word'

records =  get_records(fn, key)

for record in records:

    print record

>>>
text word text text
text text text text

Mar 27 '07 #6

ghostdog74

511

Recognized Expert Contributor

Oops - I misread OP that a record is in between asterisks instead of each line. This is basically the same as ghostdog74's post:

Expand|Select|Wrap|Line Numbers

....

fList = [i for i in re.split(r'\*', open(fn).read()) if i != '']

...

one minor issue here is, you are splitting on only 1 "*" and the output will have lots of '' , due to many "*" being splitted

Expand|Select|Wrap|Line Numbers

 
['', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '\ntext text text text\ntext text text text\ntext text text text\ntext text text text\n', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '\ntext text text text\ntext text text text\n', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '\ntext text text text\ntext text text text\ntext text text text\ntext text text text\ntext text text text\ntext text text text\ntext text text text\n', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '']

may be a better way is to split on many "*". eg

Expand|Select|Wrap|Line Numbers

re.split('\*+', open("file").read())

eg output

Expand|Select|Wrap|Line Numbers

 
['', '\ntext text text text\ntext text text text\ntext text text text\ntext text text text\n', '\ntext text text text\ntext text text text\n', '\ntext text text text\ntext text text text\ntext text text text\ntext text text text\ntext text text text\ntext text text text\ntext text text text\n', '']

Mar 28 '07 #7

bvdet

2,851

Recognized Expert Moderator Specialist

one minor issue here is, you are splitting on only 1 "*" and the output will have lots of '' , due to many "*" being splitted

Expand|Select|Wrap|Line Numbers

['', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '\ntext text text text\ntext text text text\ntext text text text\ntext text text text\n', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '\ntext text text text\ntext text text text\n', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '\ntext text text text\ntext text text text\ntext text text text\ntext text text text\ntext text text text\ntext text text text\ntext text text text\n', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '']

may be a better way is to split on many "*". eg

Expand|Select|Wrap|Line Numbers

re.split('\*+', open("file").read())

eg output

Expand|Select|Wrap|Line Numbers

['', '\ntext text text text\ntext text text text\ntext text text text\ntext text text text\n', '\ntext text text text\ntext text text text\n', '\ntext text text text\ntext text text text\ntext text text text\ntext text text text\ntext text text text\ntext text text text\ntext text text text\n', '']

That's why I excluded the '' in the list comprehension. Good point though.

Mar 28 '07 #8

PNY

New Member

Hi again,

I have a (hopefully) simple question:

Now that the code is working and is able to search and display (in the cmd prompt) the proper search results, I am now outputting to a text file, which is all fine and dandy, but for some reason, it's only ouputting the last occurence of the search word (and its associated record it is found in).

Here is what I have so far:

Expand|Select|Wrap|Line Numbers

 
import re, sys
 
fn = sys.argv[1]

key = sys.argv[2]
 
def get_records(fn, key):

     fList = [i for i in re.split(r'\*', open(fn).read()) if i != '']

     records = []

     for item in fList:

          if key in item:

               records.append(item)

     return records
 
records = get_records(fn, key)

for record in records:

     former, sys.stdout = sys.stdout, open('output.txt', 'w')

     print record

     results, sys.stdout = sys.stdout, former

     results.close()

Please help (again!) :)

That's why I excluded the '' in the list comprehension. Good point though.

Mar 28 '07 #9

PNY

New Member

Hi again,

I realized what my mistake was but I have yet another question regarding the same code.

I would like to insert a line (the 'underscore' line) in between each 'record'. How would I do that?

Mar 28 '07 #10

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