Character index in line

[gocen]

Hi, friends I want to do a bit advanced search in a file
I want to get a word and its previous and next words
I think I need the index of my search word or there any other solutions

I am waiting your suggestions, thanks

[bartonc]

Hi, friends I want to do a bit advanced search in a file
I want to get a word and its previous and next words
I think I need the index of my search word or there any other solutions

I am waiting your suggestions, thanks

A regular expression employing groups would do the trick. Basically you'd write a pattern that matched any whole word followed by your keyword followed by any word and assign them each to a group.

[bvdet]

Following are a couple of ways:

s = 'Try to find the words preceding and following a key word.'
keyw = 'preceding'
patt = re.compile(r'[a-zA-Z]+ (?=%s)|%s|(?<=%s) [a-zA-Z]+' % (keyw, keyw, keyw))
print [w.strip() for w in patt.findall(s)]
 
sList = s.split()
i = sList.index(keyw)
words = [sList[i-1], sList[i], sList[i+1]]
print words

Output:

>>> ['words', 'preceding', 'and']
['words', 'preceding', 'and']
>>>

[ghostdog74]

>>> alist=['first','second' ,'search','next','nexttwo']
>>> alist.index("search")
2
>>> alist[alist.index("search") + 1 ]
'next'
>>> alist[alist.index("search") - 1 ]
'second'
>>>