Slide 43
Slide 43 text
def levenshtein(a, b):
"Calculates the Levenshtein distance between a and b."
n, m = len(a), len(b)
if n > m:
# Make sure n <= m, to use O(min(n, m)) space
a, b = b, a
n, m = m, n
current = range(n + 1)
for i in range(1, m + 1):
previous, current = current, [i]+[0]*n
for j in range(1, n+1):
add, delete = previous[j]+1, current[j-1]+1
change = previous[j-1]
if a[j-1] != b[i-1]:
change = change + 1
current[j] = min(add, delete, change)
return current[n]