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import array
from collections import namedtuple
from pyspark import SparkContext, since
from pyspark.rdd import RDD
from pyspark.mllib.common import JavaModelWrapper, callMLlibFunc, inherit_doc
from pyspark.mllib.util import JavaLoader, JavaSaveable
from pyspark.sql import DataFrame
__all__ = ['MatrixFactorizationModel', 'ALS', 'Rating']
[docs]class Rating(namedtuple("Rating", ["user", "product", "rating"])):
"""
Represents a (user, product, rating) tuple.
>>> r = Rating(1, 2, 5.0)
>>> (r.user, r.product, r.rating)
(1, 2, 5.0)
>>> (r[0], r[1], r[2])
(1, 2, 5.0)
.. versionadded:: 1.2.0
"""
def __reduce__(self):
return Rating, (int(self.user), int(self.product), float(self.rating))
@inherit_doc
[docs]class MatrixFactorizationModel(JavaModelWrapper, JavaSaveable, JavaLoader):
"""A matrix factorisation model trained by regularized alternating
least-squares.
>>> r1 = (1, 1, 1.0)
>>> r2 = (1, 2, 2.0)
>>> r3 = (2, 1, 2.0)
>>> ratings = sc.parallelize([r1, r2, r3])
>>> model = ALS.trainImplicit(ratings, 1, seed=10)
>>> model.predict(2, 2)
0.4...
>>> testset = sc.parallelize([(1, 2), (1, 1)])
>>> model = ALS.train(ratings, 2, seed=0)
>>> model.predictAll(testset).collect()
[Rating(user=1, product=1, rating=1.0...), Rating(user=1, product=2, rating=1.9...)]
>>> model = ALS.train(ratings, 4, seed=10)
>>> model.userFeatures().collect()
[(1, array('d', [...])), (2, array('d', [...]))]
>>> model.recommendUsers(1, 2)
[Rating(user=2, product=1, rating=1.9...), Rating(user=1, product=1, rating=1.0...)]
>>> model.recommendProducts(1, 2)
[Rating(user=1, product=2, rating=1.9...), Rating(user=1, product=1, rating=1.0...)]
>>> model.rank
4
>>> first_user = model.userFeatures().take(1)[0]
>>> latents = first_user[1]
>>> len(latents)
4
>>> model.productFeatures().collect()
[(1, array('d', [...])), (2, array('d', [...]))]
>>> first_product = model.productFeatures().take(1)[0]
>>> latents = first_product[1]
>>> len(latents)
4
>>> products_for_users = model.recommendProductsForUsers(1).collect()
>>> len(products_for_users)
2
>>> products_for_users[0]
(1, (Rating(user=1, product=2, rating=...),))
>>> users_for_products = model.recommendUsersForProducts(1).collect()
>>> len(users_for_products)
2
>>> users_for_products[0]
(1, (Rating(user=2, product=1, rating=...),))
>>> model = ALS.train(ratings, 1, nonnegative=True, seed=10)
>>> model.predict(2, 2)
3.73...
>>> df = sqlContext.createDataFrame([Rating(1, 1, 1.0), Rating(1, 2, 2.0), Rating(2, 1, 2.0)])
>>> model = ALS.train(df, 1, nonnegative=True, seed=10)
>>> model.predict(2, 2)
3.73...
>>> model = ALS.trainImplicit(ratings, 1, nonnegative=True, seed=10)
>>> model.predict(2, 2)
0.4...
>>> import os, tempfile
>>> path = tempfile.mkdtemp()
>>> model.save(sc, path)
>>> sameModel = MatrixFactorizationModel.load(sc, path)
>>> sameModel.predict(2, 2)
0.4...
>>> sameModel.predictAll(testset).collect()
[Rating(...
>>> from shutil import rmtree
>>> try:
... rmtree(path)
... except OSError:
... pass
.. versionadded:: 0.9.0
"""
@since("0.9.0")
[docs] def predict(self, user, product):
"""
Predicts rating for the given user and product.
"""
return self._java_model.predict(int(user), int(product))
@since("0.9.0")
[docs] def predictAll(self, user_product):
"""
Returns a list of predicted ratings for input user and product pairs.
"""
assert isinstance(user_product, RDD), "user_product should be RDD of (user, product)"
first = user_product.first()
assert len(first) == 2, "user_product should be RDD of (user, product)"
user_product = user_product.map(lambda u_p: (int(u_p[0]), int(u_p[1])))
return self.call("predict", user_product)
@since("1.2.0")
[docs] def userFeatures(self):
"""
Returns a paired RDD, where the first element is the user and the
second is an array of features corresponding to that user.
"""
return self.call("getUserFeatures").mapValues(lambda v: array.array('d', v))
@since("1.2.0")
[docs] def productFeatures(self):
"""
Returns a paired RDD, where the first element is the product and the
second is an array of features corresponding to that product.
"""
return self.call("getProductFeatures").mapValues(lambda v: array.array('d', v))
@since("1.4.0")
[docs] def recommendUsers(self, product, num):
"""
Recommends the top "num" number of users for a given product and returns a list
of Rating objects sorted by the predicted rating in descending order.
"""
return list(self.call("recommendUsers", product, num))
@since("1.4.0")
[docs] def recommendProducts(self, user, num):
"""
Recommends the top "num" number of products for a given user and returns a list
of Rating objects sorted by the predicted rating in descending order.
"""
return list(self.call("recommendProducts", user, num))
[docs] def recommendProductsForUsers(self, num):
"""
Recommends top "num" products for all users. The number returned may be less than this.
"""
return self.call("wrappedRecommendProductsForUsers", num)
[docs] def recommendUsersForProducts(self, num):
"""
Recommends top "num" users for all products. The number returned may be less than this.
"""
return self.call("wrappedRecommendUsersForProducts", num)
@property
@since("1.4.0")
[docs] def rank(self):
"""Rank for the features in this model"""
return self.call("rank")
@classmethod
@since("1.3.1")
[docs] def load(cls, sc, path):
"""Load a model from the given path"""
model = cls._load_java(sc, path)
wrapper = sc._jvm.MatrixFactorizationModelWrapper(model)
return MatrixFactorizationModel(wrapper)
[docs]class ALS(object):
"""Alternating Least Squares matrix factorization
.. versionadded:: 0.9.0
"""
@classmethod
def _prepare(cls, ratings):
if isinstance(ratings, RDD):
pass
elif isinstance(ratings, DataFrame):
ratings = ratings.rdd
else:
raise TypeError("Ratings should be represented by either an RDD or a DataFrame, "
"but got %s." % type(ratings))
first = ratings.first()
if isinstance(first, Rating):
pass
elif isinstance(first, (tuple, list)):
ratings = ratings.map(lambda x: Rating(*x))
else:
raise TypeError("Expect a Rating or a tuple/list, but got %s." % type(first))
return ratings
@classmethod
@since("0.9.0")
[docs] def train(cls, ratings, rank, iterations=5, lambda_=0.01, blocks=-1, nonnegative=False,
seed=None):
"""
Train a matrix factorization model given an RDD of ratings given by users to some products,
in the form of (userID, productID, rating) pairs. We approximate the ratings matrix as the
product of two lower-rank matrices of a given rank (number of features). To solve for these
features, we run a given number of iterations of ALS. This is done using a level of
parallelism given by `blocks`.
"""
model = callMLlibFunc("trainALSModel", cls._prepare(ratings), rank, iterations,
lambda_, blocks, nonnegative, seed)
return MatrixFactorizationModel(model)
@classmethod
@since("0.9.0")
[docs] def trainImplicit(cls, ratings, rank, iterations=5, lambda_=0.01, blocks=-1, alpha=0.01,
nonnegative=False, seed=None):
"""
Train a matrix factorization model given an RDD of 'implicit preferences' given by users
to some products, in the form of (userID, productID, preference) pairs. We approximate the
ratings matrix as the product of two lower-rank matrices of a given rank (number of
features). To solve for these features, we run a given number of iterations of ALS.
This is done using a level of parallelism given by `blocks`.
"""
model = callMLlibFunc("trainImplicitALSModel", cls._prepare(ratings), rank,
iterations, lambda_, blocks, alpha, nonnegative, seed)
return MatrixFactorizationModel(model)
def _test():
import doctest
import pyspark.mllib.recommendation
from pyspark.sql import SQLContext
globs = pyspark.mllib.recommendation.__dict__.copy()
sc = SparkContext('local[4]', 'PythonTest')
globs['sc'] = sc
globs['sqlContext'] = SQLContext(sc)
(failure_count, test_count) = doctest.testmod(globs=globs, optionflags=doctest.ELLIPSIS)
globs['sc'].stop()
if failure_count:
exit(-1)
if __name__ == "__main__":
_test()