dict vs defaultdict

#!/usr/bin/env python

from collections import defaultdict as dd
import time

SIZE = 1000
CYCLES = 10000

def ddTest():
    d = dd(lambda:'NA')
    for x in xrange(SIZE):
        d[x]
    return d

def dTest():
    d = {}
    for x in xrange(SIZE):
        d[x] = d.get(x, 'NA')
    return d

def ddFreq():
    freq = dd(int)
    for x in xrange(SIZE):
        freq[x%7] += 1
    return freq

def dFreq1():
    freq = {}
    for x in xrange(SIZE):
        m = x%7
        freq[m] = freq.get(m, 0) + 1
    return freq

def dFreq2():
    freq = {}
    for x in xrange(SIZE):
        freq[x%7] = freq.get(x%7, 0) + 1
    return freq

def dFreq3():
    freq = {}
    for x in xrange(SIZE):
        m = x%7
        if m in freq:
            freq[m] += 1
        else:
            freq[m] = 1
    return freq

def tryList():
    freq = [0 for x in xrange(7)]
    for x in xrange(SIZE):
        freq[x%7] += 1
    return freq

def test(f):
    tStart = time.time()
    for x in xrange(CYCLES):
        result = f()
    tElapsed = time.time() - tStart
    print ("%8s took %.3f seconds and returned a %s with %s items" %
                (f.__name__, tElapsed, type(result), len(result)))
    return result

if __name__ == '__main__':
    test(ddTest)
    test(dTest)
    test(ddFreq)
    test(dFreq1)
    test(dFreq2)
    test(dFreq3)
    test(tryList)
-------------------------------------------------
Output using Python 2.7.2 on seven-year-old MBP:

  ddTest took 5.866 seconds and returned a <type 'collections.defaultdict'> with 1000 items
   dTest took 3.616 seconds and returned a <type 'dict'> with 1000 items
  ddFreq took 3.087 seconds and returned a <type 'collections.defaultdict'> with 7 items
  dFreq1 took 5.115 seconds and returned a <type 'dict'> with 7 items
  dFreq2 took 5.446 seconds and returned a <type 'dict'> with 7 items
  dFreq3 took 3.827 seconds and returned a <type 'dict'> with 7 items
 tryList took 2.432 seconds and returned a <type 'list'> with 7 items