[Tutor] searching for a value in an array (fwd)

[Erik Price]

On Thursday, September 5, 2002, at 04:20  PM, Danny Yoo wrote:

> ---------- Forwarded message ----------
> Date: Thu, 05 Sep 2002 19:21:40 +0000
> From: anthony polis <anthonypolis@hotmail.com>
> To: dyoo@hkn.eecs.berkeley.edu
> Subject: Re: [Tutor] searching for a value in an array
>
> Danny,
>
> Now I know how to search a list. But how do you pop() a list item 
> without
> knowing it's location in the list? The Python tutorial told me I have 
> to
> provide an integer in order to pop() an item out. How do I pop() an 
> item
> out when I only know it's value?

This one's easy.  You want the index() method of List objects:

 >>> somelist = ['he-man', 'man-at-arms', 'skeletor', 'zoar']
 >>> badguy = 'skeletor'
 >>> num = somelist.index(badguy)
 >>> popped = somelist.pop(num)
 >>> popped
'skeletor'
 >>> somelist
['he-man', 'man-at-arms', 'zoar']
 >>>


I'm not sure what happens if there's more than one element in the list 
that matches the argument to index.  Let's find out:

 >>> somelist
['he-man', 'man-at-arms', 'zoar']
 >>> somelist.insert(2, badguy)
 >>> somelist
['he-man', 'man-at-arms', 'skeletor', 'zoar']
 >>> somelist.append('skeletor')
 >>> somelist
['he-man', 'man-at-arms', 'skeletor', 'zoar', 'skeletor']
 >>> somelist.pop(somelist.index(badguy))
'skeletor'
 >>> somelist
['he-man', 'man-at-arms', 'zoar', 'skeletor']
 >>>


Looks like it goes for the lowest-indexed element matching the argument 
to index() but you might want to research this more.



Erik





--
Erik Price

email: erikprice@mac.com
jabber: erikprice@jabber.org