class Logistic_My:
def __init__(self, regularization, n_iterations=10):
self.regularization = regularization
self.n_iterations = n_iterations
def fit(self, X, y):
X = numpy.array(X)
self.loss = LogLossFunction()
self.loss.fit(X, y, sample_weight=y * 0 + 1)
max_cats = numpy.max(X) + 1
self.cat_biases = numpy.zeros([max_cats, X.shape[1]], dtype='float')
predictions = numpy.zeros(len(X))
for stage in range(self.n_iterations):
for column in range(X.shape[1]):
grads = self.loss.negative_gradient(predictions)
hesss = self.loss.hessian(predictions)
inds = X[:, column]
nominator = numpy.bincount(
inds, weights=grads, minlength=max_cats
) - self.regularization * self.cat_biases[:, column]
denominator = numpy.bincount(
inds, weights=hesss,
minlength=max_cats) + self.regularization
predictions -= self.cat_biases[inds, column]
self.cat_biases[:, column] += nominator / denominator
predictions += self.cat_biases[inds, column]
print stage, self.loss(predictions)
return self
def predict_proba(self, X):
X = numpy.array(X)
predictions = numpy.zeros(len(X))
for column in range(X.shape[1]):
predictions += self.cat_biases[X[:, column], column]
return predictions
def predict_train(self, X):
X = numpy.array(X)
predictions = self.predict_proba(X)
grads = self.loss.negative_gradient(predictions)
hesss = self.loss.hessian(predictions)
prediction_shift = numpy.zeros(len(X))
for column in range(X.shape[1]):
inds = X[:, column]
cum_grads = numpy.bincount(inds, weights=grads)[inds]
cum_hess = numpy.bincount(
inds, weights=hesss)[inds] + self.regularization
prediction_shift += -grads / cum_hess
return predictions + prediction_shift
def fit(self, X_cat, y):
X_cat = numpy.array(X_cat)
self.unit_weights = numpy.random.normal(size=self.n_units)
self.cat_weights = []
for column in X_cat.T:
self.cat_weights.append(
numpy.random.normal(size=[numpy.max(column) + 1, self.n_units])
* 0.1)
loss = LogLossFunction()
loss.fit(X_cat, y, y * 0 + 1.)
unit_predictions, predictions = self.compute_all(X_cat)
# Training process
for iteration in range(self.n_iterations):
new_unit_predictions, new_predictions = self.compute_all(X_cat)
assert numpy.allclose(predictions, new_predictions)
predictions = new_predictions
assert numpy.allclose(unit_predictions, new_unit_predictions)
unit_predictions = new_unit_predictions
for unit in range(self.n_units):
# updating coefficient for unit
for updated_unit in [unit]:
grads = loss.negative_gradient(predictions)
hesss = loss.hessian(predictions)
unit_outputs = self.activation(
unit_predictions[:, updated_unit])
nom = numpy.dot(grads, unit_outputs)
denom = (numpy.dot(hesss, unit_outputs**2) +
self.regularization)
step = 0.5 * nom / denom
self.unit_weights[updated_unit] += step
predictions += step * unit_outputs
for column in range(X_cat.shape[1]):
inds = X_cat[:, column]
# updating with respect to column and unit
unit_outputs, unit_derivs, unit_hesss = self.act_grad_hess(
unit_predictions[:, unit])
unit_weight = self.unit_weights[unit]
grads = loss.negative_gradient(predictions) * unit_weight
hesss = loss.hessian(predictions) * unit_weight**2
cat_grads = grads * unit_derivs
cat_hesss = hesss * (unit_derivs**2) + grads * unit_hesss
max_cats = self.cat_weights[column].shape[0]
nominator = numpy.bincount(inds,
weights=cat_grads,
minlength=max_cats)
nominator -= self.regularization * self.cat_weights[
column][:, unit]
cat_steps = nominator/ \
(numpy.bincount(inds, weights=cat_hesss.clip(0), minlength=max_cats) + self.regularization)
cat_steps *= 1.5
self.cat_weights[column][:, unit] += cat_steps
predictions -= self.unit_weights[unit] * unit_outputs
unit_predictions[:, unit] += cat_steps[inds]
unit_outputs = self.activation(unit_predictions[:, unit])
predictions += self.unit_weights[unit] * unit_outputs
print iteration, unit, column, loss(predictions)
return self
class StallsFM(BaseEstimator, ClassifierMixin):
def __init__(self,
learning_rate=1.0,
regularization=100.,
n_units=10,
iterations=30,
n_thresholds=10,
max_overlap=20,
sign=+1):
self.learning_rate = learning_rate
self.regularization = regularization
self.bias_regularization = regularization * 0.1
self.n_units = n_units
self.iterations = iterations
self.n_thresholds = n_thresholds
self.loss = LogLossFunction()
self.max_overlap = max_overlap
self.sign = sign
self.unit_signs = numpy.ones(n_units) * sign
def decompose_data(self, X, fit=False):
# hack to support both pandas and numpy.arrays
X = pandas.DataFrame(X)
if fit:
self.is_sequential = numpy.array(
[column.dtype == 'float' for name, column in X.iteritems()])
self.codings = []
self.codings.append([0])
for name, column in X.iteritems():
if column.dtype == 'float':
self.codings.append(
numpy.percentile(
column,
numpy.linspace(0, 100,
self.n_thresholds + 1)[1:-1]))
else:
self.codings.append(numpy.unique(column))
X_categoricals = []
X_categoricals.append(numpy.zeros(len(X), dtype=int))
for is_seq, coding, (name, column) in zip(self.is_sequential,
self.codings[1:],
X.iteritems()):
if is_seq:
X_categoricals.append(numpy.searchsorted(coding, column))
else:
X_categoricals.append(
(numpy.searchsorted(coding, column) + 1) *
numpy.in1d(column, coding))
return numpy.array(X_categoricals).T
def compute_grad_hess(self, predictions):
return self.loss.negative_gradient(predictions), self.loss.hessian(
predictions)
def fit(self, X, y):
self.classes_, y = numpy.unique(y, return_inverse=True)
assert len(self.classes_) == 2, 'only two classes supported'
X_cat = self.decompose_data(X, fit=True)
self.cat_biases = [
numpy.zeros(len(coding) + 1) for coding in self.codings
]
self.cat_representations = [
numpy.random.normal(size=[len(coding) + 1, self.n_units]) * 0.1
for coding in self.codings
]
self.connections = numpy.zeros([X_cat.shape[1], self.n_units])
max_overlap = min(self.max_overlap, X_cat.shape[1])
self.connections[:] = generate_connections(X_cat.shape[1],
self.n_units,
n_overlap=max_overlap)
return self.partial_fit(X, y, restart=True)
def partial_fit(self, X, y, restart=False):
assert isinstance(
X, pandas.DataFrame), 'only pandas.DataFrames are accepted'
assert numpy.in1d(y, self.classes_).all()
y = numpy.searchsorted(self.classes_, y)
assert len(X) == len(y)
self.loss.fit(X, y, sample_weight=numpy.ones_like(y))
X_cat = self.decompose_data(X, fit=False)
unit_signs = self.unit_signs
self.losses = []
for iteration in range(self.iterations):
if iteration % 1 == 0:
biases, representations, representations_sq = self.compute_representations(
X_cat)
new_predictions = self.compute_prediction(
biases, representations, representations_sq, unit_signs)
if iteration > 0:
assert numpy.allclose(predictions, new_predictions)
predictions = new_predictions
for category_biases, category_representations, column, connection in \
zip(self.cat_biases, self.cat_representations, X_cat.T, self.connections):
# fitting biases with exact step
minlen = len(category_biases)
grads, hesss = self.compute_grad_hess(predictions)
total_grads = numpy.bincount(column,
weights=grads,
minlength=minlen)
total_hesss = numpy.bincount(column,
weights=hesss,
minlength=minlen)
updates = (total_grads -
self.bias_regularization * category_biases) / (
total_hesss + self.bias_regularization)
category_biases[:] += updates
biases += updates[column]
predictions += updates[column]
for unit in numpy.arange(self.n_units):
unit_sign = unit_signs[unit]
if unit_sign == 0 or connection[unit] == 0:
continue
grads, hesss = self.compute_grad_hess(predictions)
predictions -= unit_sign * representations[:, unit]**2
predictions += unit_sign * category_representations[
column, unit]**2
representations[:,
unit] -= category_representations[column,
unit]
total_grads = numpy.bincount(column,
weights=(2 * unit_sign) *
representations[:, unit] *
grads,
minlength=minlen)
total_hesss = numpy.bincount(
column,
weights=4 * representations[:, unit]**2 * hesss,
minlength=minlen)
nominator = total_grads - self.regularization * category_representations[:,
unit]
denominator = total_hesss + self.regularization
# TODO iterative update here with penalty for is_seq
unit_update = self.learning_rate * nominator / denominator
category_representations[:, unit] += unit_update
category_representations[:, unit] = numpy.clip(
category_representations[:, unit], -1, 1)
representations[:,
unit] += category_representations[column,
unit]
predictions += unit_sign * representations[:, unit]**2
predictions -= unit_sign * category_representations[
column, unit]**2
self.losses.append(self.loss(predictions))
print(iteration, self.losses[-1])
return self
def compute_prediction(self, biases, representations, representations_sq,
unit_signs):
return biases + (representations**2
).dot(unit_signs) - representations_sq.dot(unit_signs)
def compute_representations(self, X_cat):
biases = numpy.zeros(len(X_cat), dtype='float')
representations = numpy.zeros([len(X_cat), self.n_units],
dtype='float')
representations_sq = numpy.zeros([len(X_cat), self.n_units],
dtype='float')
for cat_biases, cat_representations, column, connection in \
zip(self.cat_biases, self.cat_representations, X_cat.T, self.connections):
biases += cat_biases[column]
representations += cat_representations[column] * connection[
None, :]
representations_sq += (cat_representations**
2)[column] * connection[None, :]
return biases, representations, representations_sq
def decision_function(self, X):
X_cat = self.decompose_data(X, fit=False)
biases, representations, representations_sq = self.compute_representations(
X_cat)
return self.compute_prediction(biases, representations,
representations_sq, self.unit_signs)
def predict_proba(self, X):
result = numpy.zeros([len(X), 2])
result[:, 1] = scipy.special.expit(self.decision_function(X))
result[:, 0] = 1 - result[:, 1]
return result
def predict(self, X):
return numpy.argmax(self.predict_proba(X), axis=1)