Create Sections In Python

I am newbie to Python. I have large file with repetitive string through the logs Example: abc def efg gjk abc def efg gjk abc def efg gjk abc def efg gjk Expected Result ---------

Solution 1:

If a section is defined by the starting line, you can use a generator function to yield sections from an input iterable:

def per_section(iterable):
    section = []
    for line in iterable:
        if line.strip() == 'abc':
            # start of a section, yield previousif section:
                yield section
            section = []

        section.append(line)

    # lines done, yield lastif section:
        yield section

Use this with an input file, for example:

withopen('somefile') as inputfile:
    for i, section inenumerate(per_section(inputfile)):
        print'------- section {} ---------'.format(i)
        print''.join(section)

If sections are simply based on the number of lines, use the itertools grouper recipe to group the input iterable into groups of a fixed length:

from itertools import izip_longest

defgrouper(iterable, n, fillvalue=None):
    "Collect data into fixed-length chunks or blocks"# grouper('ABCDEFG', 3, 'x') --> ABC DEF Gxx
    args = [iter(iterable)] * n
    return izip_longest(fillvalue=fillvalue, *args)

withopen('somefile') as inputfile:
    for i, section inenumerate(grouper(inputfile, 4, '\n')):
        print'------- section {} ---------'.format(i)
        print''.join(section)

Solution 2:

To make it simple (as you say: one record every 4 lines):

with open ('yourfile', 'r') as f: lines = [x for x in f]
whilelines:
    print ('----------------------------------')
    print (lines [:4] )
    lines = lines [4:]

Solution 3:

Since you have a known starting point, you can trigger section headers whenever you see the section start:

>>> section = 0>>> withopen('bigdata.txt') as f:
        for line in f:
            if'abc'in line:
                section += 1print ('Section' + str(section)).center(55, '-')
            print line


------------------------Section1-----------------------
abc
defefg
gjk
------------------------Section2-----------------------
abc
defefg
gjk
------------------------Section3-----------------------
abc
defefg
gjk
------------------------Section4-----------------------
abc
defefg
gjk