Performance issue

[Shalabh Chaturvedi]

Tom Carrick wrote:
> Hi,
> 
> In my attempted learning of python, I've decided to recode an old
> anagram solving program I made in C++. The C++ version runs in less
> than a second, while the python takes 30 seconds. I'm not willing to
> think it's just python being slow, so I was hoping someone could find
> a faster way of doing this. Also, I was wondering if there was a more
> builtin, or just nicer way of converting a string to a list (or using
> the sort function on a list) than making a function for it.

<code snipped>

Others have already given a good commentary and alternate suggestions.
Here is some more (and some disagreements):

* Know your data structures (and how long different operations take).
Like don't do del L[0] unless required. This generally comes from
experience (and asking on this list).

* list(any_sequence_here) will build a list from the sequence. There are
usually easy ways of converting built-in types - the Python docs will
help you here.

* Try to write code as close to an english description of the problem as
possible. For example 'for word in words:' rather than using counters
and []. This is usually faster, clearer and IMO an important ingredient
of being 'Pythonic'.

Anyway here's my rendition of your program:

###
anagram = raw_input("Find anagrams of word: ")
lanagram = list(anagram)
lanagram.sort()
sorted_anagram = ''.join(lanagram).lower()

f = open('/usr/share/dict/words', 'r')

found = []

for word in f:
     word = word.strip('\n')
     if len(word)==len(sorted_anagram):
	sorted_word = list(word)
	sorted_word.sort()
	sorted_word = ''.join(sorted_word)
         if sorted_word == sorted_anagram:
	    found.append(word)

print "Anagrams of %s:" % anagram

for word in found:
     print word
###

Hopefully it is fast enough.

Shalabh