#!/usr/bin/python
# -*- coding: UTF-8 -*-
users={"Angelica":{"Blues Traveler":3.5,"Broken Bells":2.0,"Norah Jones":4.5,"Phoenix":5.0,"Slightly Stoopid":1.5,"The Strokes":2.5,"Vampire Weekend":2.0},
"Bill":{"Blues Traveler":2.0,"Broken Bells":3.5,"Deadmau5":4.0,"Phoenix":2.0,"Slightly Stoopid":3.5,"Vampire Weekend":3.0},
"Chan":{"Blues Traveler":5.0,"Broken Bells":1.0,"Deadmau5":1.0,"Norah Jones":3.0,"Phoenix":5.0,"Slightly Stoopid":1.0},
"Dan":{"Blues Traveler":3.0,"Broken Bells":4.0,"Deadmau5":4.5,"Phoenix":3.0,"Slightly Stoopid":4.5,"The Strokes":4.0,"Vampire Weekend":2.0},
"Hailey":{"Broken Bells":4.0,"Deadmau5":1.0,"Norah Jones":4.0,"The Strokes":4.0,"Vampire Weekend":1.0},
"Jordyn":{"Broken Bells":4.5,"Deadmau5":4.0,"Norah Jones":5.0,"Phoenix":5.0,"Slightly Stoopid":4.5,"The Strokes":4.0,"Vampire Weekend":4.0},
"Sam":{"Blues Traveler":5.0,"Broken Bells":2.0,"Norah Jones":3.0,"Phoenix":5.0,"Slightly Stoopid":4.0,"The Strokes":5.0},
"Veronica":{"Blues Traveler":3.0,"Norah Jones":5.0,"Phoenix":4.0,"Slightly Stoopid":2.5,"The Strokes":3.0}
}
def manhattan(rating1,rating2):
"""Computes the Manhattan distance,Both rating1 and rating2 are
dictionaries of the form {'The Strokes':3.0,'Slightly Stoopid':2.5 ...}"""
distance = 0
for key in rating1:
if key in rating2:
distance += abs(rating1[key]-rating2[key])
return distance
print manhattan(users['Hailey'],users['Veronica'])
print manhattan(users['Hailey'],users['Jordyn'])
print
def computeNearestNeighbor(username,users):
"""creates a sorted list of users based on their distance to username"""
distances = []
for user in users:
if user != username:
distance = manhattan(users[user],users[username])
distances.append((distance,user))
# sort based on distance -- closest first
distances.sort()
return distances
print computeNearestNeighbor("Hailey",users)
print
def recommend(username,users):
"""Give list of recommendations"""
# first find nearest neighbor rated that user didn't
nearest = computeNearestNeighbor(username,users)[0][1]
recommendations = []
# now find bands neighbor rated that user didn't
neighborRatings = users[nearest]
userRatings = users[username]
for artist in neighborRatings:
if not artist in userRatings:
recommendations.append((artist,neighborRatings[artist]))
# using the fn sorted for variety - sort is more efficient
return sorted(recommendations,key=lambda artistTuple:artistTuple[1],reverse=True)
print recommend('Hailey',users)
print recommend('Sam',users)
print recommend('Angelica',users)
