start reading from certain line

[antar2]

I am a starter in python and would like to write a program that reads
lines starting with a line that contains a certain word.
For example the program starts reading the program when a line is
encountered that contains 'item 1'


The weather is nice
Item 1
We will go to the seaside
....

Only the lines coming after Item 1 should be read

Thanks!

[Diez B. Roggisch]

Re: start reading from certain line

antar2 wrote:

I am a starter in python and would like to write a program that reads
lines starting with a line that contains a certain word.
For example the program starts reading the program when a line is
encountered that contains 'item 1'
>
>
The weather is nice
Item 1
We will go to the seaside
...
>
Only the lines coming after Item 1 should be read

Start reading each line, and skip them until your criterion matches. Like
this:

def line_skipper(pr edicate, line_iterable):
for line in line_iterable:
if predicate(line) :
break
for line in line_iterable:
yield line

Diez

[Tim Cook]

Re: start reading from certain line


On Wed, 2008-07-09 at 03:30 -0700, antar2 wrote:

I am a starter in python and would like to write a program that reads
lines starting with a line that contains a certain word.
For example the program starts reading the program when a line is
encountered that contains 'item 1'


The weather is nice
Item 1
We will go to the seaside
...

Only the lines coming after Item 1 should be read

file=open(filen ame)
while True:
line=file.readl ine()
if not line:
break

if 'Item 1' in line:
print line


HTH,
Tim


--
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Join the OSHIP project. It is the standards based, open source
healthcare application platform in Python.

http://www.openehr.org/wiki/display/dev/Python+developer%27s+page

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[Tim Cook]

Re: start reading from certain line

On Wed, 2008-07-09 at 03:30 -0700, antar2 wrote:

I am a starter in python and would like to write a program that reads
lines starting with a line that contains a certain word.
For example the program starts reading the program when a line is
encountered that contains 'item 1'


The weather is nice
Item 1
We will go to the seaside
...

Only the lines coming after Item 1 should be read

file=open(filen ame)
while True:
line=file.readl ine()
if not line:
break

if 'Item 1' in line:
print line


HTH,
Tim


--
*************** *************** *************** *************** **************
Join the OSHIP project. It is the standards based, open source
healthcare application platform in Python.
Home page: https://launchpad.net/oship/
Wiki: http://www.openehr.org/wiki/display/...loper%27s+page
*************** *************** *************** *************** **************

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[A.T.Hofkamp]

Re: start reading from certain line

On 2008-07-09, antar2 <desothier@yaho o.comwrote:

I am a starter in python and would like to write a program that reads
lines starting with a line that contains a certain word.
For example the program starts reading the program when a line is
encountered that contains 'item 1'
>
>
The weather is nice
Item 1
We will go to the seaside
...
>
Only the lines coming after Item 1 should be read

Not possible at most OSes, file reading always starts at the first character at
the first line. Also, most OSes don't understand the 'line' concept natively, a
file is just a long sequence of characters to them (end-of-line is also just a
character, namely '\n' (or '\r\n' if you are using Windows).

So you have to read the entire file, then throw away the bits you don't want to
keep. Luckily, Python does understand what a 'line' is, which makes the prblem
simpler.

Have a look at the readline() function (or the readlines() function if your
file is not too long). That should give you a start.



Albert

[norseman]

Re: start reading from certain line

Tim Cook wrote:

On Wed, 2008-07-09 at 03:30 -0700, antar2 wrote:

>I am a starter in python and would like to write a program that reads
>lines starting with a line that contains a certain word.
>For example the program starts reading the program when a line is
>encountered that contains 'item 1'
>>
>>
>The weather is nice
>Item 1
>We will go to the seaside
>...
>>
>Only the lines coming after Item 1 should be read

>
file=open(filen ame)
while True:
line=file.readl ine()
if not line:
break
>
if 'Item 1' in line:
print line
>
>
HTH,
Tim
>
>
>
>
------------------------------------------------------------------------
>
--
http://mail.python.org/mailman/listinfo/python-list

=============== =============== =============== ==========

I would use:

readthem= 0
file=open(filen ame,'r')
while readthem == 0:
line=file.readl ine()
if not line:
break
if 'Item 1' in line:
readthem= 1
# print line # uncomment if 'Item 1' is to be printed
while line:
line= file.readline()
print line # see note-1 below
# end of segment

The first while has lots of needed tests causing lots of bouncing about.
May even need more tests to make sure it is right tag point. As in if
'Item 1' accidentally occurred in a line previous to intended one.
The second while just buzzes on through.
If the objective is to process from tag point on then processing code
will be cleaner, easier to read in second while.

note-1:
in this form the line terminators in the file are also printed and then
print attaches it's own EOL (newline). This gives a line double spacing
effect, at least in Unix. Putting the comma at the end (print line,)
will stop that. You will need to modify two lines if used. Which to use
depends on you.


Steve
norseman@hughes .net

[Steven D'Aprano]

Re: start reading from certain line

On Wed, 09 Jul 2008 09:59:32 -0700, norseman wrote:

I would use:
>
readthem= 0
file=open(filen ame,'r')
while readthem == 0:
line=file.readl ine()
if not line:
break
if 'Item 1' in line:
readthem= 1
# print line # uncomment if 'Item 1' is to be printed
while line:
line= file.readline()
print line # see note-1 below
# end of segment

Ouch! That's a convoluted way of doing something which is actually very
simple. This is all you need:

outfile = open('filename' , 'r')
for line in outfile:
if 'item 1' in line.lower():
print line
break
for line in outfile:
print line


If you don't like having two loops:

outfile = open('filename' , 'r')
skip = True
for line in outfile:
if 'item 1' in line.lower():
skip = False
if not skip:
print line


And if you want an even shorter version:

import itertools
outfile = open('filename' , 'r')
for line in itertools.dropw hile(
lambda l: 'item 1' not in l.lower(), outfile):
print line



--
Steven

[jstrick]

Re: start reading from certain line

Here's a simple way to do it with a minimum amount of loopiness (don't
forget to use 'try-except' or 'with' in real life):

f = open("item1.txt ")

for preline in f:
if "Item 1" in preline:
print preline,
for goodline in f:
# could put an end condition with a 'break' here
print goodline,

f.close()

[Iain King]

Re: start reading from certain line

On Jul 10, 2:45 pm, jstrick <jstr...@mindsp ring.comwrote:

Here's a simple way to do it with a minimum amount of loopiness (don't
forget to use 'try-except' or 'with' in real life):
>
f = open("item1.txt ")
>
for preline in f:
    if "Item 1" in preline:
        print preline,
        for goodline in f:
            # could put an end condition with a 'break' here
            print goodline,
>
f.close()

No

[Iain King]

Re: start reading from certain line

On Jul 10, 4:54 pm, Iain King <iaink...@gmail .comwrote:

On Jul 10, 2:45 pm, jstrick <jstr...@mindsp ring.comwrote:
>

Here's a simple way to do it with a minimum amount of loopiness (don't
forget to use 'try-except' or 'with' in real life):

>

f = open("item1.txt ")

>

for preline in f:
    if "Item 1" in preline:
        print preline,
        for goodline in f:
            # could put an end condition with a 'break' here
            print goodline,

>

f.close()

>
No

Ignore that