Created
May 14, 2012 22:28
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sim-distance in python
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# Returns a distance-based similarity score for person1 and person2 | |
def sim_distance(prefs,person1,person2): | |
# Get the list of shared_items | |
si={} | |
for item in prefs[person1]: | |
if item in prefs[person2]: | |
si[item]=1 | |
# if they have no ratings in common, return 0 | |
if len(si)==0: return 0 | |
# Add up the squares of all the differences | |
sum_of_squares=sum([pow(prefs[person1][item]-prefs[person2][item],2) | |
for item in prefs[person1] if item in prefs[person2]]) | |
return 1/(1+sum_of_squares) |
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