On 2014-08-27 16:53, Rodrick Brown wrote:
> *I'm confused why the former function runs significantly faster when
> wc1() builds the hash on a single pass and doesn't waste memory of
> returning an array of strings? *
>
> *I would think wc2() to be slower what's going on here? *
>
>
> #!/usr/bin/env python
>
> s = "The black cat jump over the bigger black cat"
>
>
> def wc1():
> word=""
> m={}
> for c in s:
> if c != " ":
> word += c
String-building a character-at-a-time is slow. Also, it doesn't
produce the same results as wc2() does. Check
if wc1() == wc2():
print("Success")
else:
print("doh!")
> def wc2():
> m={}
> for c in s.split():
> if m.has_key(c):
> m[c] += 1
> else:
> m[c] = 1
> return(m)
The thing that surprises me is that using collections.Counter() and
collections.defaultdict(int) are also slower than your wc2():
from collections import defaultdict, Counter
def wc3():
return Counter(s.split())
def wc4():
m = defaultdict(int)
for c in s.split():
m[c] += 1
return m
-tkc
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