def estimate_precision(self, decomposition, train, validation, k=30):
"""
Compute prec@k for a sample of training rows.
Parameters
==========
decomposition : WARPDecomposition
The current decomposition.
train : scipy.sparse.csr_matrix
The training data.
k : int
Measure precision@k.
validation : dict or int
Validation set over which we compute precision. Either supply
a dict of row -> list of hidden cols, or an integer n, in which
case we simply evaluate against the training data for the first
n rows.
Returns
=======
prec : float
Precision@k computed over a sample of the training rows.
Notes
=====
At the moment this will underestimate the precision of real
recommendations because we do not exclude training cols with zero
ratings from the top-k predictions evaluated.
"""
if isinstance(validation, dict):
have_validation_set = True
rows = validation.keys()
elif isinstance(validation, (int, long)):
have_validation_set = False
rows = range(validation)
else:
raise ValueError('validation must be dict or int')
r = decomposition.reconstruct(rows)
prec = 0
diff = 0
sample_count = 0
for u, ru in izip(rows, r):
predicted = ru.argsort()[::-1][:k]
if have_validation_set:
actual = validation[u]
#actual = []
#for (index, rating) in validation[u]:
# actual.append(index)
# diff += pow(ru[index] - rating, 2)
# sample_count += 1
else:
actual = train[u].indices[train[u].data > 0]
prec += metrics.prec(predicted, actual, k, True)
rmse = diff / (sample_count - 1)
return float(prec) / len(rows), rmse
def estimate_precision(self,decomposition,train,validation,k=30):
"""
Compute prec@k for a sample of training rows.
Parameters
==========
decomposition : WARPDecomposition
The current decomposition.
train : scipy.sparse.csr_matrix
The training data.
k : int
Measure precision@k.
validation : dict or int
Validation set over which we compute precision. Either supply
a dict of row -> list of hidden cols, or an integer n, in which
case we simply evaluate against the training data for the first
n rows.
Returns
=======
prec : float
Precision@k computed over a sample of the training rows.
Notes
=====
At the moment this will underestimate the precision of real
recommendations because we do not exclude training cols with zero
ratings from the top-k predictions evaluated.
"""
if isinstance(validation,dict):
have_validation_set = True
rows = validation.keys()
elif isinstance(validation,(int,long)):
have_validation_set = False
rows = range(validation)
else:
raise ValueError('validation must be dict or int')
r = decomposition.reconstruct(rows)
prec = 0
diff = 0
sample_count = 0
for u,ru in izip(rows,r):
predicted = ru.argsort()[::-1][:k]
if have_validation_set:
actual = validation[u]
#actual = []
#for (index, rating) in validation[u]:
# actual.append(index)
# diff += pow(ru[index] - rating, 2)
# sample_count += 1
else:
actual = train[u].indices[train[u].data > 0]
prec += metrics.prec(predicted,actual,k, True)
rmse = diff /(sample_count - 1)
return float(prec)/len(rows), rmse
def test_prec():
true = [2, 8, 6, 4]
predicted = [6, 5, 8, 7]
expected = [1, 0.5, 2. / 3., 0.5]
for k in range(1, 5):
assert_equal(metrics.prec([], true, k), 0)
assert_equal(metrics.prec(true, true, k), 1)
assert_equal(metrics.prec(predicted, true, k), expected[k - 1])
assert_equal(metrics.prec(true, true, 5), 0.8)
assert_equal(metrics.prec(true, true, 5, ignore_missing=True), 1)
assert_equal(metrics.prec(predicted, true, 5), 0.4)
assert_equal(metrics.prec(predicted, true, 5, ignore_missing=True), expected[3])
def test_prec():
true = [2,8,6,4]
predicted = [6,5,8,7]
expected = [1,0.5,2./3.,0.5]
for k in xrange(1,5):
assert_equal(metrics.prec([],true,k),0)
assert_equal(metrics.prec(true,true,k),1)
assert_equal(metrics.prec(predicted,true,k),expected[k-1])
assert_equal(metrics.prec(true,true,5),0.8)
assert_equal(metrics.prec(true,true,5,ignore_missing=True),1)
assert_equal(metrics.prec(predicted,true,5),0.4)
assert_equal(metrics.prec(predicted,true,5,ignore_missing=True),expected[3])