Parsing Generator Python 2

Question

Input:

@example1
abcd
efg
hijklmnopq
@example2
123456789

Script:

def parser_function(f):
    name = ''
    body = ''   
    for line in f:  
        if len(line) >= 1:
            if line[0] == '@':
                name = line  
                continue 
            body = body + line  
            yield name,''.join(body)

for line in parser_function(data_file):
    print line

Output

('@example1', 'abcd')
('@example1', 'abcdefg')
('@example1', 'abcdefghijklmnopq')
('@example2', 'abcdefghijklmnopq123456789')

Desired Output:

('@example1', 'abcdefghijklmnopq')
('@example2', '123456789')

My problem, my generator is yielding every line but i'm not sure where to reset the line. i'm having trouble getting the desired output and i've tried a few different ways. any help would be greatly appreciated. saw some other generators that had "if name:" but they were fairly complicated. I got it to work using those codes but i'm trying to make my code as small as possible

NPE · Accepted Answer · 2014-10-13 18:45:46Z

4

You need to change where you yield:

def parser_function(f):
    name = None
    body = ''    
    for line in f:  
        if line and line[0] == '@':
            if name:
                yield name, body
            name = line
        else:
            body += line  
    if name:
        yield name, body

This yields once before every @... and once at the end.

P.S. I've renamed str to body to avoid shadowing a built-in.

edited Oct 13, 2014 at 18:45

answered Oct 13, 2014 at 18:40

NPE

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4 Comments

Padraic Cunningham Over a year ago

might be worth pointing out not to use str as a variable name

NPE Over a year ago

@PadraicCunningham: Good point, let me add this to the answer. Thanks.

O.rka Over a year ago

what is the "if line and line[0] == '@'" I understand the line[0] but wouldn't the "if line" always be True?

NPE Over a year ago

@draconisthe0ry: In essence, if line checks whether the line is not empty (so that we don't try to do line[0] on an empty line).

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