generator_example.py

'''
Say you have a logger that adds empty lines between each logged
event, and each event is one more more lines. You want to iterate
over each logged event.
'''

def sectionalize(lines):
    '''
    Divide lines into sections, separated by empty lines. Technically
    you could come up with a regex and do re.split, but that's doesn't
    sound easy or fun at all
    '''
    section = []
    for line in lines:
        line = line.rstrip()
        if line: #If line is not empty, add to the section
            section.append(line)
        else: #If the line is empty, yield the section and reset it
            if section:
                yield section
            section = []

def sectionalize2(lines)
    '''
    Exactly as above, but much more concise.
    '''
    return (list(section)
        for has_data, section
        in itertools.groupby(lines,
            lambda line: bool(line.rstrip()))
        if has_data)