Python difflib test to see the difference between the different ratios.

difflibtest.py

#!/bin/env python
import difflib
import random
import string
import time

repetitions = 100000

# Pre-generate strings between 5 and 30 characters in length.
strings = [''.join(random.choice(string.ascii_uppercase + string.digits) for x in range(random.randint(10,30))) for i in range(repetitions*2)]

print strings[0]

# Test with real_quick, quick and normal in turn.
start = time.time()
for i in range(repetitions):
    s1 = strings[i]
    s2 = strings[-i-1]
    m = difflib.SequenceMatcher(a=s1,b=s2)
    m.real_quick_ratio()
end = time.time()
print 'real quick: ' + str(end-start)

start = time.time()
for i in range(repetitions):
    s1 = strings[i]
    s2 = strings[-i-1]
    m = difflib.SequenceMatcher(a=s1,b=s2)
    m.quick_ratio()
end = time.time()
print 'quick: ' + str(end-start)

start = time.time()
for i in range(repetitions):
    s1 = strings[i]
    s2 = strings[-i-1]
    m = difflib.SequenceMatcher(a=s1,b=s2)
    m.ratio()
end = time.time()
print 'normal: ' + str(end-start)

# Test with quick an normal together but only for ratios above 0.6
start = time.time()
cnt = 0
for i in range(repetitions):
    s1 = strings[i]
    s2 = strings[-i-1]
    m = difflib.SequenceMatcher(a=s1,b=s2)
    r = m.quick_ratio()
    if r > 0.6:
        m.ratio()
        cnt+=1
end = time.time()
print 'quick and normal: ' + str(end-start)
print cnt

output 1

Q0E78IKLK8PP
real quick: 1.51300001144
quick: 3.02600002289
normal: 7.86299991608
quick and normal: 3.05700016022
295

m = difflib.SequenceMatcher(a=s1,b=s2)
m.ratio()

explain this part ASAP