list item's position

[Petr Prikryl]

> On Wed, 19 Jan 2005 22:04:44 -0500, Bob Smith wrote:
> > [...] 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?

I have borrowed the bars list example from 
"Bill Mill"s solutions and here are
the two solutions...

bars = ['str', 'foobaz', 'barbaz', 'foobar']


# Solution 1: The enumerate().

for idx, bar in enumerate(bars):
    if 'bar' in bar and 'baz' in bar:
        break

bars_sliced = bars[idx:]
print bars_sliced


# Solution 2: Low level approach, testing and removing combined. In
situ.

while bars:     # some prefer len(bars) > 0, which is less magical, IMHO
    bar = bars.pop(0)                   # get and remove the first
element
    if 'bar' in bar and 'baz' in bar:
        bars.insert(0, bar)             # insert the tested back
        break                           # and finish

print bars    
         

The result is ['barbaz', 'foobar'] in both cases.   

Petr
-- 
Petr Prikryl (prikrylp at skil dot cz)