List iteration issue in Python

Question

I am working with Google Python class exercises where I am getting this issue -

def front_x(words):
  # +++your code here+++
  list = []
  for i,s in enumerate(words):
    print i,s
    if s[0] == 'x':
        list.append(words.pop(i))
  return list

print front_x(['bbb','ccc','axx','xzz','xaa'])

my loop is only iterating from 0 to 3, so print i,s is giving me values till 'xzz'.Please point where I am wrong.

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– Steven Rumbalski, Commented Apr 10, 2012 at 22:33

Amber · Accepted Answer · 2012-04-10 22:01:38Z

8

Don't modify something as you're iterating over it. words.pop(i) modifies words, which you're iterating over via enumerate().

I'd suggest looking at list comprehensions for accomplishing your apparent goal.

answered Apr 10, 2012 at 22:01

Amber

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Comments

user1277476 · Accepted Answer · 2012-04-10 22:31:52Z

0

Yes, you probably shouldn't words.pop(). The word you want is most likely in s - add that to the list instead.

Also, note that naming a list "list", will more or less erase the "list" builtin type from your local scope. It's not a make or break kind of deal, but it's something pylint would warn about.

answered Apr 10, 2012 at 22:31

user1277476

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