[Tutor] Read from large text file, find string save 1st string of each line where it appeared.

[Walter Prins]

Hi Sutanu,

On 28 December 2015 at 11:20, sutanu bhattacharya <
totaibhattacharya at gmail.com> wrote:

> {'115160371': [45349980, 22477811, 40566595, 26947037, 16178191, 12984002,
> 20087719, 19771564, 61746245, 17467721, 32233776, 31052980, 70768904,
> 16113331, 12414642]} <tutor at python.org>
>
> suppose 61746245 <tutor at python.org> is my searching string. so o/p will be
> 115160371 <tutor at python.org> (1st string). Area in between third bracket
> ([
> ]) is the searching area...
>

We are not mind readers, and as others have said, you need to provide more
of a description of what you're trying to accomplish and what version of
Python, OS etc you are using.

But, assuming Windows, Python 2.x, and assuming what described as
"searching a string" is in fact more of a looking up id's in lists of id's
held as the values in a Python dict, then simplistically/directly you could
do something as follows:

--------example.py-----------
friendsmap1 = {
       115160371: [45349980, 22477811, 40566595, 26947037, 16178191,
12984002,
                   20087719, 19771564, 61746245, 17467721, 32233776,
31052980,
                   70768904, 16113331, 12414642],
       45349980:  [22477811, 40566595, 26947037, 16178191],
       16178191:  [61746245, 17467721, 32233776, 31052980],
       31052980:  [22477811, 40566595, 32233776, 31052980]
     }

friendsmap2 = {
       16178191:  [61746245, 17467721, 32233776, 31052980],
       31052980:  [22477811, 40566595, 32233776, 31052980]
     }

def friendswith(friendsmap, friendid):
    res = [key for key, value in friendsmap.items() if friendid in value]
    return res

# Examples:
print friendswith(friendsmap1, 61746245)
print friendswith(friendsmap1, 26947037)
print friendswith(friendsmap2, 61746245)

--------example.py-----------

--------output-----------
[115160371, 16178191]
[115160371, 45349980]
[16178191]



Walter