On Wed, 19 Jan 2005 22:04:44 -0500, Bob Smith <[EMAIL PROTECTED]> wrote:
>Hi,
>
>I have a Python list. I can't figure out how to find an element's
>numeric value (0,1,2,3...) in the list. Here's an example of what I'm doing:
>
>for bar in bars:
> if 'str_1' in bar and 'str_2' in bar:
> print bar
>
>This finds the right bar, but not its list position. The reason I need
>to find its value is so I can remove every element in the list before it
>so that the bar I found somewhere in the list becomes element 0... does
>that make sense?
>
sneaky (python 2.4) one-liner (not tested beyond what you see, and not
recommended
as the best self-documenting version ;-)
>>> bars = [
... 'zero',
... 'one',
... 'str_1 and str_2 both in line two',
... 'three',
... 'four',
... 'str_1 and str_2 both in line five',
... 'last line']
>>> newbar=bars[sum(iter(('str_1' not in bar or 'str_2' not in bar for bar in
>>> bars).next, 0)):]
>>> for s in newbar: print repr(s)
...
'str_1 and str_2 both in line two'
'three'
'four'
'str_1 and str_2 both in line five'
'last line'
Alternatively:
>>> newbar=bars[[i for i,v in enumerate(bars) if 'str_1' in v and 'str_2' in
>>> v][0]:]
>>> for s in newbar: print repr(s)
...
'str_1 and str_2 both in line two'
'three'
'four'
'str_1 and str_2 both in line five'
'last line'
Alternatively:
>>> newbar = list(dropwhile(lambda x: 'str_1' not in x or 'str_2' not in x,
>>> bars))
>>> for s in newbar: print repr(s)
...
'str_1 and str_2 both in line two'
'three'
'four'
'str_1 and str_2 both in line five'
'last line'
Regards,
Bengt Richter
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