[Tutor] confusing enumerate behavior

[jitendra gupta]

On Fri, Feb 6, 2009 at 5:43 AM, Emad Nawfal (عماد نوفل)
<emadnawfal at gmail.com> wrote:
> Hi Tutors,
> I'm a little, actually a lot confused by the behavior of the enumerate
> function here. I have a text and I want to get each word within the context
> of the three preceding and the three following words.  I tried this:
> #BEGIN
> my_input = "one two three four five six seven eight nine ten"
> text = my_input.split()
> for i,v in enumerate(text):
>     line =  text[i-3], text[i-2], text[i-1], v, text[i+1], text[i+2],
> text[i+3]
>     print line
> # END
> The ouput was not as I expected. It did not start from the beginning
> (actually I had expected it to throw and exception immediately)
> ('eight', 'nine', 'ten', 'one', 'two', 'three', 'four')
> ('nine', 'ten', 'one', 'two', 'three', 'four', 'five')
> ('ten', 'one', 'two', 'three', 'four', 'five', 'six')
> ('one', 'two', 'three', 'four', 'five', 'six', 'seven')
> ('two', 'three', 'four', 'five', 'six', 'seven', 'eight')
> ('three', 'four', 'five', 'six', 'seven', 'eight', 'nine')
> ('four', 'five', 'six', 'seven', 'eight', 'nine', 'ten')
> Traceback (most recent call last):
>   File "enumerate.py", line 13, in <module>
>     line =  text[i-3], text[i-2], text[i-1], v, text[i+1], text[i+2],
> text[i+3]
> IndexError: list index out of range
> emad at emad-laptop:~/Desktop$
>
> I then though of adding dummy words to the beginning and the end and exclude
> them later like this:
> #BEGIN
> my_input = "one two three four five six seven eight nine ten"
>
> text2 = " nothing " *6 + my_input + " nothing "* 6
>
> text2 = text2.split()
> for i,v in enumerate(text2[6:-6]):
>     line =  text2[i-3], text2[i-2], text2[i-1], v, text2[i+1], text2[i+2],
> text2[i+3]
>     print line
> #END
>
> The output this time was even more confusing:
> emad at emad-laptop:~/Desktop$ python enumerate.py
> ('nothing', 'nothing', 'nothing', 'one', 'nothing', 'nothing', 'nothing')
> ('nothing', 'nothing', 'nothing', 'two', 'nothing', 'nothing', 'nothing')
> ('nothing', 'nothing', 'nothing', 'three', 'nothing', 'nothing', 'nothing')
> ('nothing', 'nothing', 'nothing', 'four', 'nothing', 'nothing', 'one')
> ('nothing', 'nothing', 'nothing', 'five', 'nothing', 'one', 'two')
> ('nothing', 'nothing', 'nothing', 'six', 'one', 'two', 'three')
> ('nothing', 'nothing', 'nothing', 'seven', 'two', 'three', 'four')
> ('nothing', 'nothing', 'one', 'eight', 'three', 'four', 'five')
> ('nothing', 'one', 'two', 'nine', 'four', 'five', 'six')
> ('one', 'two', 'three', 'ten', 'five', 'six', 'seven')
>
> Can somebody please explain what is going on here? Have I done something
> wrong? How can this be fixed?
>
> Thanks in anticipation,
> Emad
>
> _______________________________________________
> Tutor maillist  -  Tutor at python.org
> http://mail.python.org/mailman/listinfo/tutor
>
>


hello Emad

Try this if u r looking for this kind of solution
>>>my_input = "one two three four five six seven eight nine ten"
>>>text = my_input.split()
>>>for i in range(len(text)):
	if i+3>=len(text):
		print text[i-3:len(text):1]
	elif i<=2:
		print text[0:i+4]
	else:
		print text[i-3:i+4]

Output is.......
['one', 'two', 'three', 'four']
['one', 'two', 'three', 'four', 'five']
['one', 'two', 'three', 'four', 'five', 'six']
['one', 'two', 'three', 'four', 'five', 'six', 'seven']
['two', 'three', 'four', 'five', 'six', 'seven', 'eight']
['three', 'four', 'five', 'six', 'seven', 'eight', 'nine']
['four', 'five', 'six', 'seven', 'eight', 'nine', 'ten']
['five', 'six', 'seven', 'eight', 'nine', 'ten']
['six', 'seven', 'eight', 'nine', 'ten']
['seven', 'eight', 'nine', 'ten']


Jitendra Kumar
Hyderabad