How to differentiate lines with one dot and two dot?

Question

I want to extract a specific part of a sentence. My problem is that I have a list of sentences that each have different formats. For instance:

X.y.com
 x.no
 x.com
 y.com
 z.co.uk
 s.com
 b.t.com

how can I split these lines based on the number of dots they have? If I want the second part of the sentence with two dots and the first part of the sentences with one dot

Can you elaborate? So for `b.t.com` you want the `t`, but for `x.no` you wanted the `x`? — Martijn Pieters, Mar 15 '13 at 14:39

Martijn Pieters · Answer 1 · 2013-03-15T14:46:07.187

2

You want the part directly preceding the last dot; just split on the dots and take the one-but last part:

for line in data:
    if not '.' in line: continue
    elem = line.strip().split('.')[-2]

For your input, that gives:

>>> for line in data:
...     print line.strip().split('.')[-2]
... 
y
x
x
y
co
s
t

edited Mar 15 '13 at 14:46

answered Mar 15 '13 at 14:40

Martijn Pieters

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I have tried this and I keep get this error"IndexError: list index out of range – UserYmY Mar 15 '13 at 14:44
@user2058811: Then you have a line without a dotted name; updated to skip those. – Martijn Pieters Mar 15 '13 at 14:46
If the lines can contain multiple dots, `rsplit(".", 2)[-2]` should be a little bit faster as it doesn't perform unneccessary splits. Probably doesn't matter for OPs case though... – l4mpi Mar 15 '13 at 14:49
@l4mpi: I was presuming that by 'sentence' the OP actually meant 'line' and that all we find on the line is the dotted name. :-) – Martijn Pieters Mar 15 '13 at 14:50
yes the lines contain multiple dots and some of them may do not contain any. How should I skip them ? – UserYmY Mar 15 '13 at 15:27
@user2058811: I already updated the code to skip lines that do not contain any dots. – Martijn Pieters Mar 15 '13 at 15:28

score 0 · Answer 2 · answered Mar 15 '13 at 14:45

0

I would follow this logic:

For each line:

remove any spaces at beginning and end
split the line by dots
take the part before last of the splitted list

This should give you the part of the sentence you're looking for.

answered Mar 15 '13 at 14:45

Vero

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3
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2

Which is really easy to code in Python; why don't you include an example or demonstration? – Martijn Pieters Mar 15 '13 at 14:46

Facundo Casco · Accepted Answer · 2013-03-15T15:50:46.460

To anwser your question you could use count to count the number of times the '.' appears and then do whatever you need.

>>> 't.com'.count('.')
1
>>> 'x.t.com'.count('.')
2

You could use that in a loop:

for s in string_list:
    dots = s.count('.')
    if dots == 1:
        # do something here
    elif dots == 2:
        # do something else
    else:
        # another piece of code

More pythonic way to solve your problem:

def test_function(s):
    """
        >>> test_function('b.t.com')
        't'

        >>> test_function('x.no')
        'x'

        >>> test_function('z')
        'z'
    """
    actions = {0: lambda x: x
               1: lambda x: x.split('.')[0],
               2: lambda x: x.split('.')[1]}
    return actions[s.count('.')](s)

there are thousand of these lines I cannot count them seperatly — UserYmY, Mar 15 '13 at 15:29

score 0 · Answer 4 · answered Mar 15 '13 at 15:39

0

Simply use the split function.

a = 'x.com'
b = a.split('.')

This will make a list of 2 items in b. If you have two dots, the list will contain 3 items. The function actually splits the string based on the given character.

answered Mar 15 '13 at 15:39

Yedhu Krishnan

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How to differentiate lines with one dot and two dot?

4 Answers4