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How to find and extract a block from file?

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tcl76
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hi,

attached is my sample file. i want to extract all lines starting from -- num until before -- Advanced.
appreciate if anyone can show me.

thanks
johnny

Attachments sample.txt (3.17KB)
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Gribouillis
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3,456 posts since Jul 2008
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Something like

from itertools import dropwhile, takewhile

def not_advanced(line):
    return not line.startswith("-- Advanced")

def not_num(line):
    return not line.startswith("-- num")

with open("sample.txt") as lines:
    lines = takewhile(not_advanced, dropwhile(not_num, lines))
    for line in lines:
        print line
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tcl76
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thanks but output i get is:
<itertools.takewhile object at 0x0000000002B90808>

btw, what is itertools? didnt realize got this function. i'm using Python 2.6.6

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Gribouillis
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thanks but output i get is:
<itertools.takewhile object at 0x0000000002B90808>

btw, what is itertools? didnt realize got this function. i'm using Python 2.6.6

The object x returned is an iterable. You can convert to a list with list(x), or iterate with a for loop: for line in x .

Itertools is a module in a standard library which contains useful functions to manipulate iterables.

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tcl76
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you are super!
with open("sample.txt") as lines:
lines = takewhile(not_advanced, dropwhile(not_num, lines))
print lines
for line in lines:
print line

Question Answered as of 2 Years Ago by Gribouillis
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Gribouillis
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you are super!
with open("sample.txt") as lines:
lines = takewhile(not_advanced, dropwhile(not_num, lines))
print lines
for line in lines:
print line

hehe :) Add itertools to your toolbag !

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tcl76
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yes thanks for the guidance.
am now reviewing:
http://www.doughellmann.com/PyMOTW/itertools/

You
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