Which is more pythonic for array removal?

Question

I'm removing an item from an array if it exists.

Two ways I can think of to do this

Way #1

# x array, r item to remove
if r in x :
  x.remove( r )

Way #2

try :
  x.remove( r )
except :
  pass

Timing it shows the try/except way can be faster

(some times i'm getting:)

1.16225508968e-06
8.80804972547e-07

1.14314196588e-06
8.73752536492e-07

import timeit

runs = 10000
x = [ '101', '102', '103', '104', '105', 'a', 'b', 'c',
  'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', '111', '112', '113',
  'x', 'y', 'z', 'w', 'wwwwwww', 'aeiojwaef', 'iweojfoigj', 'oiowow',
  'oiweoiwioeiowe', 'oiwjaoigjoaigjaowig',
]
r = 'a'

code1 ="""
x = [ '101', '102', '103', '104', '105', 'a', 'b', 'c',
  'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', '111', '112', '113',
  'x', 'y', 'z', 'w', 'wwwwwww', 'aeiojwaef', 'iweojfoigj', 'oiowow',
  'oiweoiwioeiowe', 'oiwjaoigjoaigjaowig',
]
r = 'a'

if r in x :
  x.remove(r)
"""
print timeit.Timer( code1 ).timeit( runs ) / runs

code2 ="""
x = [ '101', '102', '103', '104', '105', 'a', 'b', 'c',
  'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', '111', '112', '113',
  'x', 'y', 'z', 'w', 'wwwwwww', 'aeiojwaef', 'iweojfoigj', 'oiowow',
  'oiweoiwioeiowe', 'oiwjaoigjoaigjaowig',
]
r = 'a'

try :
  x.remove( r )
except :
  pass
"""
print timeit.Timer( code2 ).timeit( runs ) / runs

Which is more pythonic?

Answer 1

The try/except way

Answer 2

that would be:

try:
  x.remove(r)
except ValueError:
  pass

btw, you should have tried to remove an item that is not in the list, to have a comprehensive comparison.

Answer 3

The first way looks cleaner. The second looks like a lot of extra effort just to remove an item from a list.

There's nothing about it in PEP-8, though, so whichever you prefer is the 'real' answer.

Speaking of PEP-8... having that space before the colon falls under the definition of 'extraneous whitespace'.

Answer 4

I've always gone with the first method. if in reads far more clearly than exception handling does.

Answer 5

Speed depends on the ratio of hits to misses. To be pythonic choose the clearer method.

Personally I think way#1 is clearer (It takes less lines to have an 'if' block rather than an exception block and also uses less brain space). It will also be faster when there are more hits than misses (an exception is more expensive than skipping a if block).