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How can i parse a long string that come from a .txt file every

2 characters

?

PythonNewbie
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  • Do you have a code sample of what you have tried to do so far? – danseery Jan 18 '13 at 14:59
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    I don't understand the question. A text file is a long sequence of characters. Are you asking `how can I split it up into blocks of two characters`? – Katriel Jan 18 '13 at 14:59
  • Can you explain a little better. Are you wanting every consecutive pair of characters from a file object? – Steve Jan 18 '13 at 14:59
  • Not sure what you mean here. If you start with teh string "foobar", do you want to parse it `"fo","ob","ar"` or `"fo","oo","ob","ba","ar"`? – mgilson Jan 18 '13 at 15:00
  • for every 2 letters in a example like this AB08H5F7UF i will parse like AB 08 h5 F7 UF – PythonNewbie Jan 18 '13 at 16:03

2 Answers2

2

Try 

print re.findall(r'[\S]{1,2}', "The quick brown fox jumped over the lazy dog")

>>
['Th', 'e', 'qu', 'ic', 'k', 'br', 'ow', 'n', 'fo', 'x', 'ju', 'mp', 'ed', 'ov', 'er', 'th', 'e', 'la', 'zy', 'do', 'g']

OR

print re.findall(r'.{1,2}', "The quick brown fox jumped over the lazy dog")

>>
['Th', 'e ', 'qu', 'ic', 'k ', 'br', 'ow', 'n ', 'fo', 'x ', 'ju', 'mp', 'ed', ' o', 've', 'r ', 'th', 'e ', 'la', 'zy', ' d', 'og']

Update

For you specific requirement:

>>> print re.findall(r'[\S]{1,2}', "08AB78UF")
['08', 'AB', '78', 'UF']
>>>
ATOzTOA
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2

You can just zip two strings, with a gap of one offset

>>> data = "foobar"
>>> map(''.join, zip(data, data[1:]))
['fo', 'oo', 'ob', 'ba', 'ar']

And a similar solution using itertools.izip 

>>> from itertools import izip
>>> map(''.join, izip(data, data[1:]))
['fo', 'oo', 'ob', 'ba', 'ar']

If you are using Py3.X, convert the map to LC

>>> [''.join(e) for e in  izip(data, data[1:])]
['fo', 'oo', 'ob', 'ba', 'ar']

As @Duncan mentioned, the sub-strings would overlap. In case if you want non-overlapping substrings, either refer @Duncan's answer, or @Duncan's comment or the grouper recipe

>>> [''.join(e) for e in list(izip_longest(*[iter(data)] * 2,fillvalue=''))]
['fo', 'ob', 'ar']

You can easily join the resultant list to a string

>>> ' '.join(''.join(e) for e in  izip(data, data[1:]))
'fo oo ob ba ar'
Abhijit
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  • That does the overlapping sliding window, for completeness you should add that if the OP wants to not overlap then use `zip(data[::2],data[1::2])` – Duncan Jan 18 '13 at 15:14
  • how can i send that to a output .txt the result of the map(''.join, zip(data, data[1:])) – PythonNewbie Jan 18 '13 at 16:10
  • when i save that map .... to a variable a for example and give a parse.py > parsed.txt i get : ['fo', 'oo', 'ob', 'ba', 'ar'] isntead of fo oo ob ba ar – PythonNewbie Jan 18 '13 at 16:22
  • hm ok thanks alot can you just explain why the izip receives the index of the return value [1:] why not from 1:2 or something is that a default ? – PythonNewbie Jan 18 '13 at 17:49
  • @PythonNewbie: The notation used is called `slice notation`. To learn more about it refer the [SO Post](http://stackoverflow.com/questions/509211/the-python-slice-notation). In case this answer helped you, don;t forget to accept it. – Abhijit Jan 18 '13 at 17:53